Plant Pest Database

This diagnostic database contains information about many common Missoula County plants, and the pests and diseases which affect them. It provides the Missoula County Extension Services / Missoula County Integrated Pest Management Committee guidelines for both pest monitoring and least toxic options for management of pests and diseases in the landscape and garden.

Categories

  • Plants
    • Alder
    • Apple, Crabapple
    • Apple, Crabapple
    • Ash
    • Asparagus
    • Aspen
    • Basswood, Linden
    • Beans
    • Beet
    • Birch
    • Boxelder
    • Broccoli
    • Brussel Sprouts
    • Cabbage
    • Carrot
    • Cauliflower
    • Celery
    • Chard
    • Corn
    • Cottonwood
    • Cottonwood, Poplar
    • Cucumber
    • Currant or Gooseberry
    • Currant or Gooseberry
    • Dogwood
    • Douglas Fir
    • Eggplant
    • Elm
    • Euonymus
    • Fir
    • Hackberry
    • Hawthorn
    • Honeylocust
    • Honeysuckle
    • Iris
    • Juniper
    • Kale
    • Kohlrabi
    • Lettuce
    • Lilac
    • Maple
    • Mountain Ash
    • Oak
    • Onion
    • Parsnip
    • Pea
    • Pear
    • Pepper
    • Pine
    • Potato
    • Privet
    • Pyracantha
    • Rabbitbrush
    • Radish
    • Raspberry
    • Rhubarb
    • Rose
    • Serviceberry
    • Spinach
    • Spirea
    • Spruce
    • Squash
    • Stone Fruits 2: Apricot, Cherry Chokecherry, Peach, Plum, etc.
    • Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc.
    • Strawberry
    • Sumac
    • Sycamore
    • Tomato
    • Turf
    • Virginia Creeper
    • Willow
  • Pests
    • Alternaria Leaf Blight
    • Angular Leaf Spot
    • Anthracnose
    • Aphids
    • Aphids 2
    • Apple and Thorn Skeletonizer
    • Apple Scab
    • Armillaria Root Disease
    • Army Cutworm
    • Ash Plant Bug
    • Ash Yellows
    • Asparagus Beetles
    • Aster Yellows
    • Bacterial Brown Spot
    • Bacterial Spot
    • Bacterial Wetwood
    • Bacterial Wilt
    • Beet Armyworm
    • Black Knot
    • Black Rot
    • Black Spot
    • Black Vine Weevil
    • Black Witches Broom
    • Blackleg
    • Boxelder Bugs
    • Bronze Birch Borer
    • Bronze Birch Borer
    • Brown Felt Blight
    • Brownheaded Ash Sawfly
    • Cabbage Loopers
    • Carrot Rust Fly
    • Carrot Weevil
    • Cedar Apple Rust
    • Cercospora Leaf Spot or Blight
    • Cicadas
    • Codling Moth
    • Colorado Potato Beetles
    • Conifer Seed bug (Leaffooted Bugs)
    • Cooley Spruce Gall Adelgid
    • Corn Ear Worms
    • Corn Root Worm
    • Cottonwood Borer
    • Cottonwood Leaf Beetle
    • Cucumber Beetles
    • Curly Top (Virus)
    • Cutworms
    • Cytospora Canker
    • Damping Off
    • Diamondback Moth
    • Douglas Fir Beetles
    • Downy Mildew
    • Dutch Elm Disease
    • Earwig
    • Elm Leaf Beetles
    • Engraver Beeltes
    • Eriophyid Mites
    • European Corn Borer
    • Fairy Ring
    • Fall Webworm
    • Fir Broom Rust
    • Fireblight
    • Flatheaded Borer
    • Flea Beetles
    • Forest and Western Tent Caterpillars
    • Fusarium Wilt-Yellows
    • Gall Midges
    • Gall Midges
    • Grasshoppers
    • Grey Mold
    • Harlequin Bug
    • Hollyhock Rust
    • Imported Cabbage Worm
    • Ink Spot
    • Iris Leaf Spot
    • Late Blight
    • Leaf Rusts
    • Leafcutter Bees
    • Leafhoppers
    • Leafminers
    • Leafrollers
    • Lilac / Ash Borer
    • Marssonina Leaf Spot/Blight
    • Melting Out
    • Mosaic Virus
    • Mountain Pine Beetle
    • Needle Casts
    • Peach Leaf Curl
    • Pear Psylla
    • Pear Slug - Pear Sawfly
    • Petiole Gall Aphid
    • Phytophthera Root or Crown Rot
    • Poplar Borer
    • Poplar Vagabond Aphid
    • Potato Scab
    • Powdery Mildew
    • Raspberry Crown Borer
    • Red Thread
    • Redhumped Caterpillar
    • Rhizoctonia
    • Root Maggots
    • Root-knot Nematodes
    • Rose Curculio
    • Rose Gall Wasp
    • Rose Mosaic Virus
    • Rose Rust
    • Rose Stem Girdler/Bronze Cane Borer
    • Sap Beetle
    • Sapsuckers
    • Sawfly
    • Scale
    • Septoria Leaf Spot
    • Shot Hole Disease-Coryneum Blight
    • Shothole Borer
    • Smut
    • Snailcase Bagworm
    • Snow Mold
    • Sooty Mold
    • Spider Mites
    • Spittlebugs
    • Squash Bug
    • Squash Vine Borer
    • Tarnished Plant Bug
    • Tussock moth
    • Ugly Nest Caterpillars
    • Venturia Shoot Blight
    • Verticillium Wilt
    • Western Cherry Fruit Fly
    • Western Flower Thrips
    • Western Gall Rust
    • Western Raspberry Fruitworm
    • Western Spruce Budworm
    • White Grubs
    • White Pine Blister Rust
    • White Pine Weevil
    • Wireworm
  • Abiotic Ailments
    • Chemical Injury
    • Leaf Scorch
    • Nutrient Deficiencies
Alder

Alder

(Alnus spp.)

The genus Alnus includes about 30 species of deciduous trees and shrubs in NorthAmerica, Europe, Asia, and parts of South America. The leaves are simple, alternately arranged, and most often serrated. Male and female catkins appear in the spring before the leaves emerge.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Beadlike galls on both sides of leaf surfaces Eriophyid mite

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Frothy spittlemass Spittlebugs (Clastoptera juniperina)
Cottony material Alder aphid

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Discolored areas, dead bark containing small pimple-like fruiting bodies Cytospora canker (Valsa spp.,Leucostoma spp.)

Apple, Crabapple

(Malus spp.)

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Silken tents produced. Western tent caterpillar or Fall webworm(Hyphantria cunea).
Caterpillar living within a case. Snailcase bagworm (Apterona helix).
Terminal leaves curled and tied together with silk. Fruittree leafroller or Obliquebanded leafroller.
Skeletonized leaves. Apple and thorn skeletonizer (Choreutis pariana) or Apple flea beetle (Phyllotretaspp.).
"Shothole" feeding wounds in leaf, usually with sucker growth. Apple flea beetle (Phyllotreta spp.).
Raised leafmines. Western tentiform leafminer (Phyllonorycter elmaella).
White powdery material on upper or lower surface of leaf. Powdery Mildew .
Pale green or yellow leaves. Iron chlorosis. See Nutrient Deficiencies.
Apple, Crabapple

Apple, Crabapple

(Malus spp.)

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Large holes chewed in leaves. Speckled green fruitworm, Redhumped caterpillar (Schizura concinna) , or Forest tent caterpillar.
Silken tents produced. Western tent caterpillar or Fall webworm(Hyphantria cunea).
Caterpillar living within a case. Snailcase bagworm (Apterona helix).
Terminal leaves curled and tied together with silk. Fruittree leafroller or Obliquebanded leafroller.
keletonized leaves. Apple and thorn skeletonizer (Choreutis pariana) or Apple flea beetle (Phyllotretaspp.)
"Shothole" feeding wounds in leaf, usually with sucker growth. Apple flea beetle (Phyllotreta spp.).
Raised leafmines. Western tentiform leafminer (Phyllonorycter elmaella).
White powdery material on upper or lower surface of leaf. Powdery mildew.
Pale green or yellow leaves. Iron chlorosis. See Nutrient Deficiencies.
Rust orange spots. Juniper rusts.
Black mold on surface of leaf. Apple scab (Venturia inaequalis).
Rusty blisters or scabby patches on leaves. Blister mites. See Eriophyid Mites.
Bronzing of leaves. Two-spotted spidermite or McDaniel spider mite.
Curling distortions of new growth in spring. Rosy apple aphid.
Blackened and wilted leaves. Fireblight (Erwinia amylovora).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twigs shredded by a line of multiple punctures. Cicada oviposition wounds.
Blackened, wilting, and crooked tips. Fireblight (Erwinia amylovora).
Black beetle tunneling, with small exit holes. Shothole borer.
Scales on twigs. Oystershell scale or European fruit lecnium.
Cottony insects on twigs. Woolly apple aphid or Mealbugs.
Discolored areas, dead bark containing small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Boring into trunk. Flatheaded appletree borer - (Chrysobothris mali).
Bark beetle tunneling, small exit holes. Shothole borer.
Cottony insects on trunk and/or roots. Woolly apple aphid.
Internal decay and/or shelf-like fruiting structures (conks). Decay fungus.
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).

Affecting Fruit:

Signs/Symptoms Cause
Tunneling in fruit. Codling moth (Cydia pomonella).
Scarring or scabbing of fruit. Fruittree leafroller, Hail injury, or Apple scab (Venturia inaequalis).
Pitted, scarred fruit. Tarnished Plant Bug (Lygus lineolaris).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
Discolored tissue under bark at ground line. Phytophthora root rot (Phytophthoraspp.).
Galls at ground line. Crown gall.

Affecting Roots:

Signs/Symptoms Cause
White root decay and white mycelial fans between bark and wood. Armillaria root disease (Armillaria spp.).
Ash

Ash

(Fraxinus spp.)

The genus Fraxinus is comprised of about 70 species worldwide, 16 of which are native to North America. Ashes are easy to identify because they are one of a few groups of trees that are both opposite and pinnately compound. The fruit of these trees is a single-winged samara resembling a canoe. The bark is crisscrossed with ridges and resembles a woven net.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed: normal chewing injuries, primarily confined to leaf edges. Browheaded AshSawfly (Tomostethusmulticinctus); Forest tent caterpillar (Malacosoma dissetria); Fruittree leafroller (Archips argyrospilus).
Smooth semicircular cuts made on leaf edge. Leafcutter Bees (Megachile spp.).
Blackened spotting of leaves. Ash Anthracnose (Apiognomonia spp.).
Leaflets being distorted and/or killed back. Ash plant bug (Tropidosteptes amoenus).
Flecking wounds on leaves. Ash plant bug (Tropidosteptes amoenus) or Lacebug (Corythuca spp.).
Leaves bronzed: “Brittle-leaf†condition. Eriophyid mites.
Leaflets thickened and curled at midrib. Ash midrib gall midge (Contarinia canadensis).
Leaves tightly curled and thickened. Leafcurl ash aphid (Prociphilus fraxinifolii).
General distortion of leaf, with thickened veins. Herbicide injury.
White powdery material on upper or lower surface of leaf. Powdery mildew.
Wilting of portions of tree: originating from roots. Verticillium wilt (Verticillium spp.).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twig dieback with small exit holes or ventilation holes visible. Ash bark beetles (Hylesinus spp.).
Twig dieback with small pimple-like fruiting bodies (pycnidia) in the bark. Cytospora canker (Valsa spp., Leucostoma spp.).
Witches' brooming symptoms. Ash yellows (Phytoplasma).
Scales.

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Tunneling in trunk. Lilac/Ash borer, Banded ash clear wing, (Podosesia syringa); Ash bark beetles (Hylesinus spp.); Redheaded ash borer(Neoclytus acuminatus).
Masses of caterpillars resting on bark. Forest tent caterpillar (Malacosoma disstria Hubner).
Discolored areas and dead bark containing small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood/slime flux.
Large, dead areas of bark on southwest side of trunk. Winter sunscald.
Open wounds, internal decay, swollen areas on stem. Stem decay fungi (Perenniporia fraxinophila, Phellinus punctatus, and various fungal genera).
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (Perenniporia fraxinophila, Phellinus punctatus, and various fungal genera).
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).

Affecting Flowers:

Signs/Symptoms Cause
Distorted flowers. Ash flower gall mite (Eriophyes fraxiniflora).
Asparagus

Asparagus

(Asparagus officinalis.)

Asparagus is a cool season perennial grown for its young shoots which are one of the first vegetables to harvest in the spring. Asparagus cultivars can be grouped according to spear color - dark green, whitish-green or purple. Asparagus can be planted from seed or 1-year old crowns. If your soil is heavy plant on slightly raised beds. Asparagus is very hardy and grows best at elevations up to 5,500' on sites that have moist soil and full sun. Asparagus prefers a light, deep, well-drained soil with a pH of 6.0-6.7, but will tolerate a pH over 7.0. Asparagus requires high levels of phosphorus and potassium. Do not harvest new plantings until they are at least 2 years old.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow leaves, slow growth. Nitrogen deficiency.
Yellow leaves, dwarfed plants, plants form bushy rosettes. Asparagus aphids.
Yellow leaves, wilting, dieback of crown. Fusarium wilt (Fusarium oxysporum).
Foliage turns reddish brown and drops; small reddish spots on main stems and branches. Rust.
Defoliated plants/deformed spears. Several insect pests cause this kind of injury, including Asparagus beetles.

Affecting Spears:

Signs/Symptoms Cause
Chewed stalks at soil line, seedlings clipped off at soil line. Cutworms (Noctuidae spp.).
Large lesions at base of spears or below soil line; small spears. Fusarium wilt(Fusarium oxysporum).
Spears turn brown near soil line. Phytopthora crown rot (Phytophthora spp.).
Bracts of spears are spread out. Feathering caused by high temperatures (>85° F.).
Aspen

Aspen

(Populus tremuloides)

Populus tremuloides or quaking aspens, are one of the most widely distribute tree in North America This is a broadleaf deciduous small tree with roundish leaves, white undersides, and flat petioles that cause the leaves to flutter in the wind. This tree can grow in sun or part shade, adaptable to nearly all types of soil, is fast growing, and relatively short lived.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves curled. Large aspen tortrix (Choristoneura conflictana).
Leaves curled with tent of silk produced. Western tent caterpillar (Malacosoma fragilis).
No curling or silk associated with injury. Forest tent caterpillar (Malacosoma disstria Hubner), Redhumped caterpillar(Schizura concinna), Cottonwood leaf beetle (Chrysomela scripta), or Sawflies(cimbidae).
Masses of dark, spiney caterpillars on leaves. Spiny elm caterpillar [Mourning Cloak Butterfly] (Nymphalis antiopa) - No significant damage.
Leaves spotted: Young leaves blackened. Shoot blight (Venturia tremulae) or Frost injury.
Black irregular spots on leaves. Septoria leaf spot and canker (Septoria populicola).
Dark round spot which drops out of leaf, leaving shothole appearance. Ink spot (Ciborinia whetzelii).
Black spots with yellow margins. Marssonina blight (Marssonina populi).
Rust or orange colored spots. Conifer-aspen rust (Melampspora spp.).
Underside spots with small depressions and patches of brown leaf hairs. Eriophyid mites.
Leaves generally distorted or thickened; whole leaf or set of leaves so distorted. Poplar vagabond aphid(Erisomatidae spp.).
Edge of leaf folded into a series of ridges. Eriophyid mites.
Red, thickened folds along leaf veins. Gall midge.
Leaves with serpentine, silvery tunneling. Aspen leafminer (Phyllocnistis populiella).
Sucking insects on leaves. Clear-winged aspen aphid (Chaitophorus populifoliae) or Leafhoppers.
White powdery material on upper or lower surface of leaf. Powdery mildew (Erysiphe cichoracearum).
Yellowed leaves. Root damage caused by under or over watering or Iron chlorosis.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twig dieback; Shoot curled into a shepherd’s crook. Shoot blight (Venturia tremulae).
Meandering tunnels under bark. Flatheaded borer Agrilus spp.
Twig dieback with small pimple-like fruiting bodies (pycnidia) in the bark. Cytospora canker (Valsa spp.,Leucostoma spp.).
Scales on bark. Oystershell scale (Lepidosaphes ulmi).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Areas of dead bark, with discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Small (1/6 - in) gray or brown oystershell shaped objects on bark. Oystershell scale (Lepidosaphes ulmi).
Rounded and often rough swellings on branches. Aspen gall (Diplodia tumefaciens).
Oozing liquid from wounds with clear to white oozing or frothy malodorous liquid. Bacterial wetwood/slimflux.
Orange staining ooze. Poplar borer (Saperda calcarata).
Cottony growth on branches and/or trunk. Woolly aphid.
Swellings in branches or trunk. Poplar borer (Saperda calcarata).
Tunneling with coarse sawdust often forced from opening. Poplar borer (Saperda calcarata).
Regular rows of holes in trunk.
Open wounds, internal decay, or swollen areas in stem. Stem decay fungi (Phellinus tremulae, Ganoderma applanatum, and other fungal genera).
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (Phellinus tremulae, Ganoderma applanatum, and other fungal genera).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
Stem decay fungi (Phellinus tremulae, Ganoderma applanatum, and other fungal genera). Armillaria root disease (Armillaria mellea).

Affecting Roots:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease (Armillaria mellea).
Basswood, Linden

Basswood, Linden

(Tilia spp.)

The genus Tilia consists of about 40 species of large or medium-sized deciduous trees. Trees of this genus thrive in loamy, moist, fertile soil, but will tolerate poor soils and adverse conditions. Trees of this genus vary greatly in size, shape, leaf, and growth rate. Lindens are primarily used as ornamental shade and street trees. The wood of Linden is generally not suitable for lumber as it is soft and rots readily. The name "basswood" or "bastwood" is dervided from the word bast (inner bark) that consists of long, tough fibers once used in the production of mats and clothing.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves being chewed. Fruittree leafroller (Archips argyrospila) or Speckled green fruitworm (Orthosia hibisci).
Small pouch galls form on leaf surface. Linden fingergall mite (Eriophyid mite).
Velvety patches on underside of leaves (littleleaf linden). Linden fingergall mite (Eriophyid mite).
Pale green or yellow leaves. Iron chlorosis.
Leaves strongly cupped. Herbicide injury. See Abiotic Injury..
Aphids. Linden aphid (Myzocallis tiliae).
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Large cottony insect develops in late spring. Cottony maple scale (Pulvinaria innumerabilis).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).
Beans

Beans

(Phaseolus vulgaris)

Snap beans come in various shapes and colors and are eaten in the immature stage. Dry or field beans also come in assortment of shapes and colors and are harvested for storage in the mature form. There are two kinds of snap beans: pole or bush types. Pole types produce later harvests over longer periods, but must be supported. Bush types have a more concentrated maturity and come on earlier. Beans should be planted when soil temperatures reach 60 degrees F. Beans prefer a pH of 5.5-7.0, and need adequate phosphorus and potassium for a good crop.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, curling leaf margins, wilted plants; flowers and pods drop. Large aspen tortrix (Choristoneura conflictana).
Yellow, distorted new growth. Tarnished plant bug (Lygus pratensis).
Yellow leaves, slow growth. Nitrogen deficiency.
Curled, yellow, withered leaves. Bean aphids, Bean mosaic, or Curly top.
Small reddish-brown specks, especially on leaf undersides; leaves yellow and drop. Rust.
White, stippled leaves, which later become bronzed, stunted growth. Mites.
Meandering tunnels in leaves. Leafminers.
Puckered leaves curl downwards; plants stunted. Flea beetles (Phyllotreta spp.).

Affecting Seeds, Seedlings or Roots:

Signs/Symptoms Cause
Poor germination, deformed, spindly seedlings with killed growing point. Seed corn maggots.

Affecting Fruit:

Signs/Symptoms Cause
Blossoms drop. Excessive heat or rain, or Western flower thrips (Frankliniella occidentalis).
Pitting and russeting of pods. May be due to chilling injury.
Water-soaked or brown patches on pods; yellow, blotched seeds. Bacterial blight (Pseudomonas syringae).
Holes chewed in pods. Caused by several worms including the following: Cabbage looper, Beet armyworm (Euxoa auxiliaris) , Corn earworm (Heliothis zea) , or European corn borer (Ostrinia nubilalis).

Affecting Seed, Seedling and Whole Plant:

Signs/Symptoms Cause
Stems rot near soil line and plant collapses; seeds do not germinate. Damping off.

Beet

(Beta vulgaris)

Beets can be either be directly sown into the garden once the soil has warmed to 45 degrees or can be sown into containers for later transplanting. For a continuous supply of greens and small beets, sow seed at two week intervals until two months prior to first heavy frost. Beets should be sown at a depth of 1/2-1 inch, with 2 inch spacing between plants, and 15-24 inches between rows. Beets are generally ready to harvest within 60 days, or two-three weeks sooner if transplanted.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow leaves, older first; stunted plants. Nitrogen deficiency.
Yellow, curled leaves; stunted plants. Aphids.
Purplish patches on leaves. Phosphorus deficiency(common in cool spring soils).
Brown leaf tips. May be a reaction to bright sun and heat (temperatures above 80° F.)
Tan spots with dark borders. Cercospora leaf spot (Cercospora spp.).
Meandering, white or translucent, irregular tunnels in leaves. Leafminers.
Small holes, shot-hole injury. Flea beetles (Phyllotreta spp.).

Affecting Roots:

Signs/Symptoms Cause
Internal black, dead, hard spots. Boron deficiency.
Forked roots. Forked roots.
Small, poorly developed roots. Small, poorly developed roots.
Light color and wider zoning of rings in root. High temperature and fluctuating soil moisture.
Birch

Birch

(Betula spp.)

The genus Betula is comprised of nearly 50 species of deciduous trees and shrubs, 14 of which are native to the United States. Flowers of this genera are monoecious and borne in catkins. Male catikins are formed late in the season, persist through the winter, and open in the spring. Female catkins appear with the leaves on terminal spurs-like branches. Birches are known to hybridize readily in the wild and in cultivation.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves with tan-colored, blotchy mines. Birch leafminer (Fenusa pusilla) or Aphids(several, species unknown).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Tunneling, raised, papery bark, or dieback. Bronze birch borer (Agrilus anxius Gory).
Areas of dead bark With discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Boxelder

Boxelder

(Acer negundo)

Boxelder or ash-leaved maple is a deciduous multi-stemmed tree that grows 30-50 ft. in height. The opposite leaf arrangement is characteristic to the maple family, but this species is compound (ash-like), usually 3-5 leaflets. The tree is extremely hardy, is native to riparian areas, but is adaptable to other sites.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves curled, chewed. Boxelder leafroller (Archips negundanus).
Leaves thickened around midrib. Gouty veingall midge (Continaria negundinis).
New growth is small, distorted. Eriophyid mites.
Sucking on leaves, honeydew often present. Boxelder and maple aphids (Periphyllus spp.).
Small cottony indentations on leaf underside. Eriophyid mites.
Masses of reddish eggs on leaves. Boxelder bug (Boisea trivittata).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Discolored areas, dead bark containing small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (Pholiota sp., Pleurotussp., and various fungal genera).
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (Pholiota sp., Pleurotussp., and various fungal genera).

Affecting Seeds:

Signs/Symptoms Cause
Feeding on seeds. Boxelder bug (Boisea trivittata).
Broccoli

Broccoli

(Brassica oleracea var. botrytis)

Broccoli is a hardy vegetable in the Brassicaceae (crucifer or cabbage) family. This plant can provide two crops a year as it grows during the cool seasons of the year. Transplants are recommended to give the best start for spring planting, but direct sowing can produce succesful plants. Plant seeds 1/4-1/2 inch deep or transplants slightly deeper than originally grown. The edible portion of the broccoli are the unopened, compact, inflorescences and the attached stem. When harvesting, removing the central head will stimulate the growth of side shoots to develop for later harvests.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow v-shaped spots on leaf margins with blackened veins; stems show internal black streaks. Black rot (Xanthomonas campestris).
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting. Fusarium yellows (Fusarium oxysporum).
Yellow leaves, older leaves first, slow growth. Nitrogen deficiency.
Older leaves whitish and drooping. Cold injury, wind injury.
Yellow, curled leaves; stunted plants. Aphids.
White to bronze spots, wilted leaves. Thrips.
White spotting, then brown, often distorted leaves that wilt and die. Harlequin bug (Margantia histrionica).
Light-colored spots on leaves turn papery; white mildew on leaf undersides. Downy mildew (Peronospora effusa).
Small pitted holes, shot-hole injury. Flea beetles (Phyllotreta spp.).
Large hole in leaves; outer leaves riddled, excrement found at base of cabbage head. Imported cabbage worm (Pieris rapae),Cabbage looper, Diamondback moth(Plutella xylostella), or Grasshoppers(Melanoplus spp.).
Leaves with meandering tunnels. Leafminer.

Affecting Roots:

Signs/Symptoms Cause
Yellow, stunted plants that wilt during bright, hot days and recover at night. Usually a sign of root injury. Pull up plant and check for root-knot nematodes or cabbage root maggots (below).
Irregularly shaped galls. Root-knot nematode (Meloidogyne spp.).
Roots are riddled with slimy, winding tunnels. Cabbage root maggots.

Affecting Inflorescences or Heads:

Signs/Symptoms Cause
Hollow stem, smaller, uneven head formation. Excess nitrogen, or potassium deficiency.
Black areas in center of head. Rot due to water collecting inside head.
Small heads that form prematurely (bolt). High temperature stress, poorly adapted variety, or exposure of plants to fluctuating warm/cool temperatures.
Brussel Sprouts

Brussel Sprouts

(Brassica oleracea var. gemmifera)

Brussel sprouts is one of the most hardy members of the cabbage family. It can tolerate a lower temperture (<40 F) and pH (5.5-6.8) than any of the other brassicas. Brussel sprout plants become about 2 1/2' tall, bearing may 1-2" ball-like sprouts resembling minature cabbages. Plant brussel sprouts 18" apart in rows 3' apart. Jade Cross Hybrid and Prince Marvel do well in our climate.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Tan to dark-brown leaf margins. Heat injury.
Poor sprout development. Nitrogen or potassium deficiency; poor variety choice.
Sticky, blackened sprouts. Aphids.
Holes in leaves. Imported cabbage worm (Pieris rapae) or Cabbage looper.

Affecting Roots:

Signs/Symptoms Cause
Yellow, stunted plants that wilt during bright, hot days and recover at night. Usually a sign of root injury. Pull up plant and check for root-knot nematodes or cabbage root maggots (below).
Irregularly shaped galls. Root-knot nematode (Meloidogyne spp.).
Roots are riddled with slimy, winding tunnels. Cabbage root maggots.
Cabbage

Cabbage

(Brassica oleracea var. capitata)

Cabbage is a hardy, cool season crop. There are green, red and savoy types shich come in early, midseason and late varieties. All need cool moist conditions. Most early varieties weigh about 3 pounds, miseason and late varieties weigh 4-6 pounds. Cabbage does well in fertile well-drained soils with a pH of 6.0 to 6.8. Cabbage is a heavy feeder requiring nitrogen and phosphorus in high levels. Cabbage has shallow roots and thus needs an abundance of water. Plant seedlings out a couple weeks before the last frost date 2' apart in rows 3' apart. Mulching will help conserve moisture and control weeds. Uneven moisture after heads are formed will cause splitting.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow V-shaped spots on leaf marginsheads dwarfed and often one-sided. Black rot (Xanthomonas campestris).
Stunted, wilted, yellow plants. Youngest plants and seedlings are affected. Root maggots.
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting. Fusarium yellows (Fusarium oxysporum).
Purple leaves on transplants. Usually indicates a Phosphorus Deficiency.
Older leaves yellow, shrunken stems, dark near soil line; weak plants may wilt and die. Rhizoctonia (Rhizoctonia spp.).
Black specks to larger spots on heads. Downy mildew (Peronospora effusa).
Brown leaf tips. May be a reaction to bright sun and heat (temperatures above 80° F.).
Split heads. Too much water.
Small holes, shothole injury. Flea beetles (Phyllotreta spp.).
Large hole in leaves; outer leaves riddled, excrement found at base of cabbage head. Cabbage worms (Pieris rapae) or Cabbage looper.
Carrot

Carrot

(Daucus carota var. saliva)

Carrots are a cool season crop, hardy enough to be undisturbed by light frosts in the spring and fall. A multitude of carrot cultivars exists; from short, stumpy cultivars adapted to more shallow soils, to long and thin cultivars requiring more exacting carrot growing conditions. Carrots perform best in well-aerated, deep, loose sandy loam soils with a pH of 5.5-6.8. Carrots require moderate to high levels of potassium and phosphorus, but only a moderate level of nitrogen. An abundant and even water supply is necessary for good root development. Misshapen carrots are more often a result of hard, compact soil than any pest problem.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, dwarfed young leaves, bushy growth, purpled leaves. Aster yellows (Phytoplasma).
Yellow leaves, older first; stunted plants. Nitrogen deficiency.
Yellow-bronze, curled leaves; bushy top growth. Aphids.
Dark spots with yellow borders. Cercospora leaf blight (Cercospora spp.) if younger leaves are affected. Alternaria leaf blight (Alternaria spp.) if older leaves are affected..
Seedlings clipped off at soil line. Cutworms (Noctuidae spp.).
Poor seedling emergence. Crusted soil; high temperatures.

Affecting Roots:

Signs/Symptoms Cause
Roots chewed, meandering scars allon root with a rusty-red color. Carrot rust fly (Psila rosae).
Yellow, stunted plants that wilt during bright, hot days and recover at night. Usually a sign that roots are injured. Pull up plant and check roots for Wireworms or Root-knot nematodes (see below).
Small, irregular holes scattered over surface of root; Damage usually occurs later in the season and is worse in dry years. Wireworms.
Bumps on roots and deformed carrots. Root-knot nematodes (Meloidogyne spp.).
Jagged cracks, water-soaked appearance. Freezing injury.
Forked roots. Can occur if soils are heavy, compacted, or stony; if root tips are injured; if roots are overcrowded.
Dark tunnels, often in a zig-zag pattern, on upper and outer part of root. Carrot weevil (Otiorynchus spp.).
Internal cavity spot. Calcium deficiency.
Spindly, short roots. Can be caused by potassium deficiency or excessive heat.
Poor color and taste. Caused by magnesium deficiency,phosphorus deficiency, low temperatures and excessive heat.
Small, woody, hairy, pale roots. Carrot yellows (Phytoplasma).
Green shoulders. Exposure to sunlight.
Cauliflower

Cauliflower

(Brassica oleracea var. botrytis)

Cauliflower is a cabbage relative grown for its flowerbuds,which are clustered together in a head. Cauliflower is not as cold tolerant, temperatures below 45 F can initiate flowering or bolting. Cauliflower is a heavy feeder of nitrogen and phorphorus, requiring well-drained soils with a pH of 6.4 to 7.4. Cauliflower has shallow roots requiring an abundance of water. Do not grow cauliflower where any member of the cabbage family have grown in the past 3 years. Set out transplants about the time of the last frost 18-24" apart in rows 3' apart.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Roots are riddled with slimy, winding tunnels. Cabbage root maggots.

Affecting Roots:

Signs/Symptoms Cause
Yellow v-shaped spots on leaf margins with blackened veins. Black rot (Xanthomonas campestris).
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting. Fusarium yellows (Fusarium oxysporum).
Large hole in leaves; outer leaves riddled, excrement found at base of cabbage head. Cabbage worms (Pieris rapae) or Cabbage looper.
Small holes, shothole injury. Flea beetles (Phyllotreta spp.).

Affecting Heads:

Signs/Symptoms Cause
Black specks or spots on heads. Downy mildew (Peronospora effusa).
Curds turn brown and appear watersoaked. Boron deficiency or exposure of curds to bright sun and high temperatures.
Celery

Celery

(Apium graveolens var. dulce)

Celery is a moisture-loving cool season crop, with heavy fertilizer requirements. Celery prefers a pH of 6-7,with a generous amount of compost or well-rotted manure. Celery seedlings are set out after night time temperatures are above 40 F. If the temperture is to cold it may cause seed stalk formation. Space plants 6-8" apart in rows 21/2' apart. Keep plants moist but do not mound up dirt around plants as they may rot in warm weather. Celery likes some shading in the heat of summer.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, dwarfed young leaves, bushy growth, purpled leaves. Aster yellows (Phytoplasma).
Yellow leaves, older first; stunted plants. Nitrogen deficiency.
Yellow leaves, reddish stalks. Fusarium yellows (Fusarium oxysporum).
Yellow, curled leaves. Aphids.
Yellow, distorted new growth. Tarnished plant bug (Lygus pratensis).
Mottled, yellow leaves, twisted stems, dwarfing. Celery mosaic.
Brown mottling of leaves, cross-wise cracks on stalks. Boron deficiency.
Discolored streaks on stalk. Potassium deficiency.
Rosetting of leaves. Phosphorus deficiency.
Blackening at center with death of growing points. Calcium deficiency.
Irregular yellow-brown leaf spots; sunken tan, elongated spots on stalks. Cercospora leaf blight (Cercospora spp.).
Dwarfed, rotted plants. Carrot rust fly (Psila rosae).
Chewed leaves. Several worms including carrot (or celery) worm, Armyworm (Euxoa auxiliaris) , or Cabbage loopers.
Chard

Chard

(Apium graveolens var. dulce)

Chard, better known as 'Swiss' chard is a type of beet developed for its green tops, which grow vigorously from late spring through to fall frost. Chard prefers sandy, well-drained soil with a pH of 6.5-7.5. To keep leaves tender, provide plenty of water and nitrogen. The prominent central ribs may be cut away from the rest of the leaf to be cooked and served like asparagus. The remainder of the leaf can be eaten as greens.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow leaves, older first; stunted plants. Nitrogen deficiency.
Yellow, curled leaves; stunted plants. Aphids.
Purplish patches on leaves. Phosphorus deficiency.
Brown leaf tips. May be a reaction to bright sun and heat (temperatures above 80° F.).
Tan spots with dark borders. Cercospora leaf spot (Cercospora spp.).
Yellow, rotted leaves; light-colored spots on upper leaf surface, white mildew on leaf undersides. Downy mildew (Peronospora effusa).
Stunted, crinkled leaves. Curly top.
White or translucent, irregular tunnels in leaves. Leafminers.
Small holes, shot-hole injury. Flea beetles (Phyllotreta spp.).
Chewed terminals and leaves. Beet armyworm (Euxoa auxiliaris).
Corn

Corn

(Zea mays var. saccharata)

Sweet corn is challenging to grow, but is well worth the fresh picked rewards. It loses sweetness soon after picking. Temperature and moisture are vital to growing corn. Plant corn when soil temperatures are > 50 F, with rich light soils in a pH range of 6-7. Corn is a very heavy feeder and does well with compost worked into the soil before planting and side dressing of nitrogen rich fertilizer when its 12" tall and when it begins to silk. Plant corn in four rows so it is easily pollinated by the wind. Irrigate corn consistantly and well, especially when plants are young. Corn kernals can be white, bicolor or yellow. Cultivar groups are classified as normal sugary, sugar enhanced, and supersweet. Supersweet cultivars must be isolated by 25' from all other sweet corn or cross-pollination may result in starchy, tough kernels. Warming the soil before planting with clear plastic will increase germination.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Numerous small holes, bleached out spots or stripes on leaves. Flea beetles(Phyllotreta spp.).
Ragged leaf margins on young plants; plants cut at base of stem. Cutworms (Noctuidae spp.).
Holes in leaves, shot-hole leaf injury. Corn earworm (Heliothis zea ) , European corn borer (Ostrinia nubilalis) , or Armyworm (Euxoa auxiliaris).
Round, brown raised spots on leaves. Rust.
Mottled, stunted new leaves; poor kernel formation at base of ear. Maize dwarf mosaic virus.
White-black, puffed-out growths on ears, tassels, and stems. Smut (Ustilago maydis).
Older leaves purple on young plants. Phosphorus deficiency.
Yellow leaves, older first; stunted plants. Nitrogen deficiency.
Yellow, curled leaves; stunted plants. Aphids.

Affecting Ears:

Signs/Symptoms Cause
Irregular ears with corky bands at the base of kernels. Boron deficiency, phosphorus deficiency, or potassium deficiency.
Large, chewed areas or dry, brown exposed kernels at the top of ear. Birds.
Hollowed-out kernels in the upper half of the ear. Sap Beetles.
Damage to developing kernels at ear tips. Corn earworm.
Bored ears and stalks, with damage seen anywhere on ear (not just at tips). European corn borers (Ostrinia nubilalis) and/or Armyworms (Euxoa auxiliaris).

Affecting Seed, Seedling and Whole Plant:

Signs/Symptoms Cause
Wilted, stunted plants and/or spotty, poor stands. May be due to several soil-dwelling pests including: Wireworm, Seed corn maggots, or, less commonly, white grubs.
Wilting, stunting, and poor germination. Corn root worms.
Cottonwood

Cottonwood

(Populus spp., except Aspen)

Cottonwood trees are all known for rapid growth. They grow best with regular deep watering, ensuring roots grow deeply to become drought tolerant. Do not plant near water lines or sewers as their roots are invasive. There are 30-35 species of poplars and numerous hybrids and named cultivars. Cottonwoods are commonly used in windbreak and fence row plantings.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed. Cottonwood leaf beetle (Chrysomela scripta), Spiny elm caterpillar (Nymphalis antiopa), Fall webworm (Hyphantria cunea), or Tussock moth (Dasychira vagans).
Webbing/Tents produced. Fall webworm (Hyphantria canea),Western tent caterpillar (Malacosoma californicum), or Forest tent caterpillar(Malacosoma disstria).
Small holes chewed in leaves. Flea beetles (Chrysomelidae).
Leaves tunneled. Aspen leafminer (Phyllocnistis populiella).
Leaves spotted with young leaves blackened. Shoot blight(Venturia populina) or Frost injury.
Black spots with yellow margins. Marssonina blight (Marssonina populi).
Black, irregular spots. Septoria leaf spot and canker (Septoria popolicole).
Blackish-brown round spot, which drops out of leaf, leaving shothole-like appearance. Ink Spot (Ciborinia whetzelii).
Rust to orange colored spots. Conifer-aspen rust (Melampsora spp.).
Yellowed leaves. Root damage caused by under or over watering, or Iron chlorosis.
White powdery material on upper or lower surface of leaves. Powdery mildew (Erysiphe cichoracerum).
Leaf petioles, veins with swelling. Petiole-gall aphids (Pemphigus spp.).
Leaves generally distorted and thickened. Poplar vagabond aphid (Mordwilkoja vagabunda).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Hollow swellings on new shoots. Petiole-gall aphids (Pemphigus spp.).
Terminal leaves distorted into thickened mass. Poplar vagabond aphid(Mordwilkoja vagabunda).
Twigs shredded in irregular row. Cicada oviposition injury (Platypeisidae).
Swellings in twigs, small branches. Poplar gall borer (Superda inornata) or Hail injury (upper surface only).
Scales on twigs, branches. Oystershell scale (Lepidosophes ulmi).
Catkins grossly distorted and enlarged. Cottonwood catkin gall mite (Eriophyes neoessigi).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (various species).
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (various species)
Masses of caterpillars resting on bark. Forest tent caterpillar (Malacosoma disstria).
Tunneling in trunk, often with orange staining ooze. Cottonwood borer (Plectodera scalator),Poplar borer (Saperda calcarata),Cottonwood Crown Borer, or American hornet moth (Sesia tibialis).
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood/slime flux.
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Insects visiting oozing sap from trunk. Flies (various families).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease (Armillaria mellea).
Gall at ground line. Crown gall (Agrobacterium tumefaciens).
Cottonwood, Poplar

Cottonwood, Poplar

(Populus spp. excluding P. tremuloides)

Cottonwood trees are all known for rapid growth. They grow best with regular deep watering, ensuring roots grow deeply to become drought tolerant. Do not plant near water lines or sewers as their roots are invasive. There are 30-35 species of poplars and numerous hybrids and named cultivars. Cottonwoods are commonly used in windbreak and fence row plantings.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed. Cottonwood leaf beetle (Chrysomela scripta), Spiny elm caterpillar (Nymphalis antiopa), Fall webworm (Hyphantria cunea), or Tussock moth (Dasychira vagans).
Webbing/Tents produced. Fall webworm (Hyphantria canea),Western tent caterpillar (Malacosoma californicum), or Forest tent caterpillar(Malacosoma disstria).
Small holes chewed in leaves. Flea beetles (Chrysomelidae).
Leaves tunneled. Aspen leafminer (Phyllocnistis populiella).
Leaves spotted with young leaves blackened. Shoot blight (Venturia populina) or Frost injury.
Black spots with yellow margins. Marssonina blight (Marssonina populi).
Black, irregular spots. Septoria leaf spot and canker (Septoria popolicole).
Blackish-brown round spot, which drops out of leaf, leaving shothole-like appearance. Ink spot (Ciborinia whetzelii).
Rust to orange colored spots. Conifer-aspen rust (Melampsora spp.).
Yellowed leaves. Root damage caused by under or over watering, or Iron chlorosis.
White powdery material on upper or lower surface of leaves. Powdery mildew (Erysiphe cichoracerum).
Leaf petioles, veins with swelling. Petiole-gall aphids (Pemphigus spp.).
Leaves generally distorted and thickened. Poplar vagabond aphid (Mordwilkoja vagabunda).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Hollow swellings on new shoots. Petiole-gall aphids (Pemphigus spp.).
Terminal leaves distorted into thickened mass. Poplar vagabond aphid (Mordwilkoja vagabunda).
Twigs shredded in irregular row. Cicada oviposition injury (Platypeisidae).
Swellings in twigs, small branches. Poplar gall borer (Superda inornata) or Hail injury (upper surface only).
Scales on twigs, branches. Oystershell scale (Lepidosophes ulmi).
Catkins grossly distorted and enlarged. Cottonwood catkin gall mite (Eriophyes neoessigi).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (various species).
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (various species).
Masses of caterpillars resting on bark. Forest tent caterpillar (Malacosoma disstria).
Tunneling in trunk, often with orange staining ooze. Cottonwood borer (Plectodera scalator),Poplar borer (Saperda calcarata),Cottonwood Crown Borer, or American hornet moth (Sesia tibialis).
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood/slime flux.
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Insects visiting oozing sap from trunk. Flies (various families).

Affecting Roots:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease(Armillaria mellea).
Gall at ground line. Crown gall (Agrobacterium tumefaciens).
Cucumber

Cucumber

(Cucumis sativus)

Cucumbers are members of the cucurbit family, which are a warm weather, sun requiring vegetable. Types of cucumbers include long, smooth, green slicing types; small pickling types; and roundish, yellow, mild-flavored lemon cucumbers. Novelties include oriental(long, slim, very mild), Armenian(actually long, curving, pale green, ribbed melon with cucumber look and mild flavor) and English. Cucumbers grow best in soils with a pH of 5.5-7.0 and 60°F. Set transplants out or plant seeds when all danger of frost is past. In small gardens they can be trained to climb a fence. Provide plenty of moisture and harvest fruits while they are dark green, if they turn yellow the plant quits producing.

Additional Information

Affecting Fruit:

Signs/Symptoms Cause
Small, brown, angular fruit spots. Angular leafspot (Pseudomonas syringae).
Brown and sunken zoned spots. Alternaria (Alternaria spp.).
Circular, black, sunken cankers. Anthracnose.
Misshapen, yellow mottled fruit, often with a bitter taste. Mosaic virus.
Fruit wilts and shrivels. Bacterial wilt (Erwinia tracheiphila).
Fruit is narrow at stem end. Potassium deficiency.
Fruit has a dull bronze color. Phosphorus deficiency.
Fruit is light colored. Nitrogen deficiency.
Dark pitting of fruit. Cold damage.

Affecting Leaves and Vines:

Signs/Symptoms Cause
Plants wilt, foliage looks burned; preceded by pale green areas forming on leaves. Squash bug (Anasa tristus).
Sudden wilting of a runner or part of a runner. Squash vine borer (Melitta satyriniformis).
Leaves wilt, yellow, and curl. High Aphid populations.
Vines wilt and die gradually, starting with newer leaves; no leaf yellowing is present. Bacterial wilt (Erwinia tracheiphila).
Small, pitted leaf holes on young plants. Cucumber beetles (Acalymma vittata).
Distorted, Yellow spots on leaves with mottling and wrinkling of older leaves. Mosaic viruses.
Older leaves mottled yellow between veins. Downy mildew (Peronospora effusa).
Powdery, white spots on upper surface of leaves especially. Powdery mildew.
Leaf spots that begin as water-soaked, then turn gray, die and drop out leaving foliage with a shot-hole appearance. Angular leafspot (Pseudomonas syringae).
If water-soaked, yellow spots turn brown. Anthracnose.
Currant or Gooseberry

Currant or Gooseberry

(Ribes spp.)

Currants and Gooseberries belonging to the Ribes species, are a multi-stem shrub grown for their fruit used for pies, preserves or sauces. Yellowish flowers are in drooping clusters are formed in the spring followed by red or white fruit in summer. They are easily grown; tolerant of any good soil; full sun to light shade. Their height ranges within the varieties from 4-8'. Propagate from softwood cuttings taken in June-July.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
White flecks in leaves. Rose leafhoppers (Edwardsiana rosae) orTwospotted spider mite.
White powdery material on upper or lower surface of leaf. Powdery mildew (Mycosphaerella sp.).
Leaves puckered, often thickened and discolored. Currant aphid (Amphorophora agathonica Hottes or Cryptomyzus ribis).
Leaves chewed. Imported currantworm (Nematus ribesi) or Western tent caterpillar (Malacosoma californicum).
Hollow swelling in leaves. Gall-making sawfly.
Orange to yellow colored spots on underside of leaf. Leaf rusts (various species).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Tunneling in stems or branches. Current borer (Synanthedon tipuliformis) or Bronze cane borer (Agrilus aurichaleceus).

Affecting Fruit:

Signs/Symptoms Cause
Maggot in fruit. Currant fruit fly (Epochra canadensis).
Currant or Gooseberry

Currant or Gooseberry

(Ribes spp.)

Currants and Gooseberries belonging to the Ribes species, are a multi-stem shrub grown for their fruit used for pies, preserves or sauces. Yellowish flowers are in drooping clusters are formed in the spring followed by red or white fruit in summer. They are easily grown; tolerant of any good soil; full sun to light shade. Their height ranges within the varieties from 4-8'. Propagate from softwood cuttings taken in June-July.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
White flecks in leaves. Rose leafhoppers (Edwardsiana rosae) orTwospotted spider mite.
White powdery material on upper or lower surface of leaf. Powdery mildew (Mycosphaerella sp.)
Leaves puckered, often thickened and discolored. Currant aphid (Amphorophora agathonica Hottes or Cryptomyzus ribis).
Leaves chewed. Imported currantworm (Nematus ribesi) or Western tent caterpillar (Malacosoma californicum).
Hollow swelling in leaves. Gall-making sawfly.
Orange to yellow colored spots on underside of leaf. Leaf rusts (various species).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Tunneling in stems or branches. Current borer (Synanthedon tipuliformis) or Bronze cane borer (Agrilus aurichaleceus).

Affecting Fruit:

Signs/Symptoms Cause
Maggot in fruit. Currant fruit fly (Epochra canadensis).
Dogwood

Dogwood

(Cornus spp.)

Dogwoods are deciduous trees and shrubs preferring a moist well drained soil in full sun or shade. Some varieties can grow to 20 in height. Dogwoods have a fibrous root system and grows rapidly. Some cultivars have yellow or red twigs adding landscape interest in the winter months. Propagation by seed or softwood cuttings. Some species are used as hedges, for erosion control and the fruit is utilized by wildlife.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed. Redhumped caterpillar (Schizura concinna).
New leaves curled. Sunflower aphid (Aphis helianthi).
Black spots on leaves. Septoria leaf spot and canker (Septoria cornicola).
White powdery material on upper or lower surface of leaf. Powdery mildew.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Scales. Oystershell scale (Lepidosaphes ulmi).
Dead areas on stem. Nectria canker (Nectria sp.) or Root collar rot (Phytophthora sp.).

Affecting Fruit:

Signs/Symptoms Cause
Feeding in or on berries. Conifer seed bugs (Leptoglossus occidentalis).
Douglas Fir

Douglas Fir

(Pseudostuga menziesii)

Douglas fir have a sharply pyramidal form when young; widely grown and cherished as a Christmas tree. Grows 70-130' height with densely set, soft dark green or blue-green needles 1-1½" long, radiating out in all directions from twigs and branches. Sweet fragrance when crushed. Reddish brown cones are oval, about 3" long, and have obvious pronged bracts, that hang down. Douglas fir prefers neutral to slightly acid, well drained moist soils. At one time the most important lumber tree in the US.

Additional Information

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Witches’ brooms on branches, small shoots emerging from branch. Dwarf mistletoe.
Large galls. Bacteria-like gall or Burl.
Aphids. Giant conifer aphids (Cinara spp.).
Tunneling in trunk, branches. Douglas-fir beetle (Dendroctonus pseudotsugae).
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (Fomitopsis pincola,Cryptoporus volvatus and various fungal genera).

Affecting Roots:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease (Armillaria mellea).

Affecting Needles:

Signs/Symptoms Cause
Newer needles being chewed. Douglas-fir tussock moth (Orgyia pseudotsugata) or Western spruce budworm (Choristoneura occidentalis).
Needles with discolored spotting, various color spots. Needle casts (various fungi).
Needles with discolored spotting, rust or orange color spots. Conifer aspen rust (Melampsora spp.).
Needles to exterior of tree bleached or brown, developing late winter. Winter dessication.
Brown felt-like materials on needles or branches (high elevations). Brown felt blight (Herpotricha juniperi).
Needles bent, twisted. Cooley spruce gall adelgid (Adelges cooleyi) or Frost injury.
Woolly aphids on needles. Cooley spruce gall adelgid (Adelges cooleyi).
Whole tree fades, reddens. Douglas-fir beetle (Dendroctonus pseudotsugae).

Affecting Cones:

Signs/Symptoms Cause
Flowers tunneled. Western spruce budworm (Choristoneura occidentalis).
Woolly aphids on cones. Cooley spruce gall adelgid (Adelges cooleyi).
Sucking on developing cones. Conifer seed bugs (Leptoglossus occidentalis).

Affecting Buds:

Signs/Symptoms Cause
Buds tunneled. Western spruce budworm (Choristoneura occidentalis).
Eggplant

Eggplant

(Solanum melongena var. esculentum)

Eggplants, widely grown as a meat substitute in the Mediterranean region, are less common here because they require very warm weather - optimum growing temperatures of 70-85°. Eggplants come in various shapes from thin and long to short and blocky, and colors, white to purple. The plants grow 2 to 3 feet tall, with each plant bearing four or more fruits. Eggplants prefer well-drained, fertile sandy loams, high in organic matter. Eggplants require more nitrogen than tomatoes, with moderate amounts of phosphorus and potassium. Eggplant does best at a pH of 6.0-6.8, but will tolerate a pH as low as 5.5. Eggplants have a high moisture requirement. Set out plants when night temperatures are above 55°, 2½ feet apart. They will perform better with a plastic mulch to hold in heat and moisture. Pick all fruit before they mature; otherwise they will stop producing.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Large holes in leaves, skeletonized leaves; plants and leaflets stripped. Colorado potato beetle (Leptinotarsa decemlineata).
Tiny, pitted holes in leaves, leaves may have a lacelike appearance and turn dull, dry green. Flea beetle (Phyllotreta spp.).
Yellow leaves turn brown and die. Lacebug.
Yellow leaves accompanied by gradual wilting and browning between leaf veins. Verticillium wilt (Verticillium spp.).
Yellow mottling of leaves; curling and malformation of leaves. Tobacco mosaic virus or cucumber mosaic virus.
Circular, dark spots on leaves. Alternaria Leaf Blight.
Large holes in leaves. Grasshoppers (Melanoplus spp.).

Affecting Fruit:

Signs/Symptoms Cause
Dry, brown chew marks. Colorado potato beetle (Leptinotarsa decemlineata).
Elm

Elm

(Ulmus spp.)

Deciduous fast growing trees easily grown in most soils. Best with normal watering, but will tolerate low moisture conditions at expense of good growth, plant health. Root systems are aggressive and close to surface. Branch crotches often narrow, easily split. The elms are subject to many pests, which are fatal and control measures are not effective or available. Elms were once used extensively as street and lawn trees. The American elm was overplanted and when Dutch elm disease struck it devastated the elm populations. The species of elms grow between 50-100' tall. Some species have a weedy nature with their papery winged seedpods dispersing over a wide area. Once used in windbreaks and shelterbelts, new cultivars have been developed for resistance to Dutch Elm disease.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves skeletonized, primarily on leaf underside. Elm leaf beetle (larvae) (Xanthogaleruca luteola).
Holes chewed through leaves. Elm leaf beetle (Xanthogaleruca luteola).
Leaves irregularly chewed. Spiny elm caterpillar (Nymphalis antiopa);Fruittree leafroller (Archips argyrospila),Forest tent caterpillar (Malacosoma disstria), or Fall webworm (Hyphantria cunea).
Masses of dark, spiny caterpillars on leaves. Spiny Elm Caterpillar - Morning Cloak Butterfly (Nymphalis antiopa) - No significant damage.
New leaves small, twisted. Eriophyid mites (Eriophyidae) or Phenoxy herbicide injury. See Chemical Injury.
Leaves curled, thickened. Woolly aphids (Eriosoma spp.).
Leaves with white flecks. Leafhoppers (Erythroneura spp.).
Pale green or yellow leaves. Iron chlorosis.
Sucking insects on leaves, often with associated honeydew. European elm scale (Gossyparia spurai) or Elm leaf aphid (Myzocallis ulmifolii).
Yellowing, wilting foliage. Scale "flagging" - European elm scale, Dutch elm disease (Ophiostoma ulmi), or Verticillium wilt (Verticillium spp.).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Scales. European fruit lecanium(Parthenolecanium corni) or European elm scale (Gossyparia spuria).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Borers. Elm borer (Saperda tridentata Oliver) or Flatheaded appletree borer(Chrysobothris femorata)
Areas of dead bark With discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Open wounds, internal decay, or swollen areas on stem. Stem decay fungi (Collybia velutipes,Phellinus igniarius and various genera).
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (Collybia velutipes, Phellinus igniarius and various genera).
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood / slime flux.
Euonymus

Euonymus

(Euonymus spp.)

Euonymus are evergreen or deciduous shrubs that are valued for their foliage, texture and form. Many uses as a landscape plant in hedges, specimen and border plantings. It's interesting foliage color and interesting stem character are best seen when planted in full sun to light shade. Requires only moderate watering after establishment. The best growth is seen in well-drained soils, is pH adaptable, with a fibrous root system. Easily propagated from seeds.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Notches cut in edge of leaves. Black vine weevil (Otiorhynchus sulcatus).
Leaves mined, edges curled with webbing. Lilac leafminer (Caloptilia syringella).
New leaves curled, thickened. Bean aphids (Aphis fabae).
Flecking, discoloration. Twospotted spider mite (Tetranychus urticae Koch).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
Chewing of roots. Black vine weevil (Otiorhynehus sulcatus).
Fir

Fir

(Abies spp.)

Firs are evergreen trees in nature that are tall, erect, symmetrical with uniformly spaced branch whorls. The needlelike leaves are linear, long flattened and blunt-tipped. Female seed cones produced erect at the tips of last season's growth. Firs are slow growing especially when planted outside their native habitats. Firs require moist, well drained acidic soils and high atmospheric moisture with cooler temperatures. There are many landscape cultivars among the various species including prostrate, compact, pendulous, contorted, fastigiate, yellow-foliaged and blue-foliaged types. Native to Montana are the grand and subalpine firs.

Additional Information

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Large aphids on branches, twigs. Giant conifer aphids (Cinara spp.).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Bark beetles. Fir engraver (Scolytus ventralis Le Conte).
Borers. Flatheaded fir borer (Melanophila drummondi).
Witches brooms on branches, orange to yellow colored pustules on needles. Fir broom rust (Melampsorella caryophyllacearum).
Large aphids on branches or trunk. Giant conifer aphids (Cinara spp.).
Fungal fruiting bodies (mushroom, conks) present. Stem decay fungi (various species).
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (various species).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease (Armillaria mellea).

Affecting Needles:

Signs/Symptoms Cause
New needles being chewed. Douglas-fir tussock moth (Orgyia pseudotsugata) or Western spruce budworm (Choristoneura occidentalis).
Needles to exterior of tree bleached or brown, developing late winter. Winter dessication.
Various colored spots. Needlecast diseases.
Orange colored pustules on needles. Fir broom rust (Melampsorella caryophyllacearum).
Brown felt-like material on needles, branches. Brown felt blight (Herpotrichia juniperi).
Needles being mined. White fir needleminer (Epinotia meritana).
Aphids on needles. Giant conifer aphids (Cinara spp.).

Affecting Buds:

Signs/Symptoms Cause
Buds tunneled. Western Spruce budworm (Choristoneura occidentalis).
Hackberry

Hackberry

(Celtis spp.)

Hackberrys are in the Ulmaceae family as are elms. Hackberry tolerates a wide variety of soils and moisture conditions. Common hackberry grows to form a 50' tall and wide canopy with 2-5" bright green, finely toothed leaves. The older bark forms narrow corky projecting ridges which are sometimes reduced to wart like projections. A good tree for park and large area use.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves being chewed. Fruittree leafroller (Archips argyrospila) or Spiny elm caterpillar, usually in masses (Nymphalis antiopa).
Leaves with white flecking (net-leaf hackberry). Lacebugs (Corythucha spp.).
Leaves yellowed. Iron chlorosis or other deficiency, or Root damage from under or over watering.
Leaves with large, conspicuous raised areas. Hackberry nipplegall maker (Pachypsylla celtidismamma).
Leaves with small raised areas. Hackberry blistergall maker (Pachypsylla celtidivescula Riley) .

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Cellophane-like webbing in late summer. Spider mites (Tetranychidae spp.).
Twigs deformed into dense witches’ broom. Eriophyid mites / Powdery mildew complex.

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Borers / Bark beetles. Flatheaded appletree borer(Chrysobothris femorata).
Clear to white oozing or frothy maladorous liquid exiting from wounds. Bacterial wetwood / Slime flux.
Hawthorn

Hawthorn

(Crataegus spp.)

Hawthorns are members of the rosaceae family, are known for their pretty spring flowers and showy fruit in summer and fall. Most hawthorns grow to 20-30' tall & wide, with thorns up to 2" long. Hawthorns are tolerant of many soils but they should be well drained, pH adaptable. Douglas hawthorn which grows more like a large shrub is native to Montana.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Blackened and wilting leaves. Fireblight (Erwinia amylovora).
Pale green or yellow leaves. Iron chlorosis.
Caterpillars associated with webbing. Fall webworm (Hyphantria canea) or Western tent caterpillar (Malacosoma californicum).
Chewing leaves. Apple aphid (Aphis pomi).
Reddish spotting on upper surface/orange pustules, spiny eruption on underside. Cedar-Apple Rust (Gymnosporangium rusts).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Blackened, wilting, and crooked tips. Fireblight (Erwinia amylovora).
White, wax-covered insects. Mealybug (Pseudococcidae) or Wooly hawthorn aphid (Eriosoma crateagi).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood and slime flux.
Honeylocust

Honeylocust

(Gleditsia triacanthos)

Honeylocust are fast growing deciduous trees in the Leguminosae family. Honeylocust grow to heights of 35-70', with open spreading branches and leaves divided into many oval ¾-1½" long leaflets. Honeylocust are late to leaf out; leaves turn yellow and drop early in fall. Honeylocust are easily transplanted, withstanding a broad range of soil conditions, drought tolerant once established, and salt conditions, and hardy from zones 4-9. Honeylocust make for a nice lawn tree, with light shade under tree allowing grass to grow well under it.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Caterpillars chewing on leaves. Fruittree leafroller (Archips argyrospila).
Leaflets distorted into thickened pods. Honeylocust podgall midge (Dasineura gleditschiae).
Honeydew appearing on leaves. Cottony maple scale (nymph stage on leaves) - (Pulvinaria innumerabilis).
Leaves turn bronze, may prematurely drop. Honeylocust spider mite(Platytetranychus multidigituli) or Honeylocust rust mite (Aculops spp.).
Yellowed leaves. Root damage cased by under or over watering.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Tips of twigs thickened, may have dieback. Honeylocust podgall midge (severe injury killing growing points).
Scales. Cottony maple scale (Pulvinaria innumerabilis).
Twigs with small splintering wounds. Putnam's cicada [egg laying wounds] - (Platypedia putnami).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Areas of dead bark (cankers) or Discoloration and small pimple-like fruiting bodies (pycnidia) in the bark. Cytospora canker (Valsa spp.,Leucostoma spp.) .
Amber colored gummy exudate (gummosis). Stress response from drought, sunscald, collar rot, cankers or other causes.
Honeysuckle

Honeysuckle

(Lonicera spp.)

Honeysuckles are deciduous shrubs or vines with tubular, often fragrant flowers. Easily grown in sun or light shade, adaptable to many soil types and pH levels, and prefers a well-drained soil. Many types of birds use the flowers and fruit as sources of food. They perform well with average summer watering and a severe pruning to keep in shape and looking refreshed.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves curled and with blackened margins. Honeysuckle blight.
Leaves tightly curled, associated bunchy growth. Honeysuckle witches' broom aphid (Hyadaphis tartaricae).
Early season leaves curled, yellow. Aphids.
White powdery material on upper or lower surface of leaf. Powdery mildew.
Iris

Iris

(Iris spp.)

Iris is a diverse group of about 200 species, varying in flower color and form, cultural needs, and blooming season, although majority flower in spring or early summer. Leaves swordlike or grasslike; flowers showy. The four main groups are: bulbous, crested, beardless and bearded. The last three have rhizomes as roots. The most widely grown are tall bearded; in which many new varieties appear every year.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellowing leaves. Nitrogen deficiency or natural senescence.
Yellow leaves. Aphids.
Spots on leaves. Iris Leaf Spot.
Juniper

Juniper

(Juniperus spp.)

Junipers are evergreen trees and shrubs with fleshy, berry-like cones. Foliage is needlelike, scalelike, or both. Foliage color varies from a dark green to light green, blue, sliver-blue, yellow and shades in between. Junipers are the most widely used woody plants in the west; there's a form for almost every landscape. Juniper types include ground cover forms a few inches to 2-3', taller prostrate shrubs, and taller spreading or erect tree types. Junipers succeed in all soils except waterlogged. They are best grown in full sun to light shade.

Additional Information

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twig galls. Juniper rusts (Gymnosporangium spp.).
Twig dieback. Grasshoppers (Melanoplus spp.)Phytophthera Root or Crown Rot.
Large aphids on branches, twigs. Giant conifer aphids (Cinara spp.).
Brown felt-like material on needles and branches (higher elevations only). Brown felt blight (Herpotricha juniperi).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Witches' brooms or branch galls. Juniper broom rust (Gymnosporangium speciosum).
Large aphids on branches, trunk. Giant conifer aphids (Cinara spp.).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease (Armillaria mellea).
Brown, discolored roots. Phytophthera Root or Crown Rot.

Affecting Needles:

Signs/Symptoms Cause
Frothy masses on needles. Juniper spittlebug (Clastoptera juniperinaBell)..
Honeydew present. Aphids.
Needles chewed and fragments tied with webbing. Juniper webworm (Dichomeris marginella).
Aphids on needles. Giant conifer aphids (Cinara spp.).
Pale green or yellow needles. Iron chlorosis.
Needles tips bleached or brown. Winter dessication or Vole injury.
Needles become grayish, with small flecks. Spruce spider mite (Oligonychus ununguis).
Scales on needles. Juniper scale (Carulaspis juniperi Bouche) or Fletcher scale (Parthenolecanium fletcheri).
Kale

Kale

(Brassica oleracea var. acephala)

Kale is a very hardy member of the cabbage family, with green or purple leaves, in which the central leaves do not form a head. Kale can tolerate a lower temperature(<40°F) and pH(5.5-6.8) than can other brassicas. In fact frost improves the taste. Kale can be grown like cabbage, though its culture is easier because it is not as often besieged by pests who seem to prefer some of the other brassicas.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow v-shaped spots on leaf margins. Black rot (Xanthomonas campestris).
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting. Fusarium yellows (Fusarium oxysporum).
Yellow leaves, older leaves first, slow growth. Nitrogen deficiency.
Yellow leaves. Cold weather.
Yellow, curled leaves; stunted plants. Aphids.
Brown leaves that wilt and die. Harlequin bug (Margantia histrionica).
Tan to dark-brown leaf margins. Heat injury.
Small holes, shothole injury. Flea beetles (Phyllotreta spp.).
Large holes in leaves; outer leaves riddled. Cabbage worms (Pieris rapae) or Cabbage looper.

Affecting Roots:

Signs/Symptoms Cause
Yellow, stunted plants that wilt during bright, hot days and recover at night. Cabbage root maggots.
Kohlrabi

Kohlrabi

(Brassica oleracea var. gongylodes)

Kohlrabi looks like a kind of above ground turnip and is another member of the cabbage family. Kohlrabi is eaten raw or cooked as a vegetable. Plant seeds in spring, ½" deep, 6" apart. Keep plants well watered as they are very shallow rooted. Kohlrabi should be ready for harvest in 8 weeks when they are 2-2½ in size.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow v-shaped spots on leaf margins. Black rot (Xanthomonas campestris).
Yellow leaves, older leaves first, slow growth. Nitrogen deficiency.
Tan to dark-brown leaf margins. Heat injury.
Small, pitted holes in leaves. Flea beetles (Phyllotreta spp.).
Large holes in leaves. Cabbage worms (Pieris rapae).

Affecting Roots:

Signs/Symptoms Cause
Yellow, stunted plants that wilt during bright, hot days and recover at night. Check roots for the following: slimy, winding tunnels mean Cabbage root maggots.
Lettuce

Lettuce

(Lactuva sativa)

The 3 most common types of lettuce are: leaf or bunching, head (including butterhead and crisphead), and cos or romaine. Lettuce will happily grow just about anywhere with ample sunlight, cool nights (50-60°F), loose soil, and plenty of moisture. Optimum lettuce growing temperatures are 60-65° F. To high of temperatures will cause seed stalk formation or bolting, however there are many bolt-resistant cultivars. Lettuce is a heavy nitrogen feeder with a limited root system. Plant every 30 days for a consistent supply.

Additional Information

Affecting Leaves and Heads:

Signs/Symptoms Cause
Bleached center leaves are dwarfed, curled or twisted. Aster yellows (Phytoplasma).
Yellow or pale leaves, stunted plants. Leaf hoppers.
Yellow, distorted new growth. Tarnished plant bug (Lygus pratensis).
Yellow leaves, slow growth, bitter taste. Nitrogen deficiency.
Yellow, curled leaves. Aphids.
Light green or yellow crinkled leaves with enlarged veins. Big vein: caused by a virus-like organism.
Dull gray-green to brown leaves. Thrips.
Mottled, ruffled leaves; stunted plants. Mosaic viruses.
Leaf margins turn brown and die. Tipburn, prevalent in hot weather.
Browning and dwarfing of plant; Velvety, white growth on leaves. Downy mildew.
Powdery dust on upper leaf surfaces. Powdery mildew.
Outer leaf margins tan, blistering of leaves. Freezing injury.
Wilting, sudden collapse of outer leaves on mature plants. Sclerotinia drop.
Lower leaves and midribs rot near the base of the plant first. Bottom rot or Rhizoctonia (Rhizoctoniaspp.).
Slimy, rotted heads. Gray Mold (Botrytis cinerea).
Midrib discolored. High temperatures (> 80° F.).
Lettuce malformed. Boron or phosphorus deficiency.
Brown center and rosetting. Calcium deficiency.
Small holes in leaves, shot-hole injury. Flea beetles (Phyllotreta spp.).
Large hole in leaves; excrement found at base of head. Cabbage looper, Imported cabbage worm(Pieris rapae) , Beet armyworm, and Corn earworms (Heliothis zea).
Large holes in leaves with slimy trails. Slugs and snails.
White or translucent, irregular tunnels in leaves. Leafminers.
Lilac

Lilac

(Syringa spp.)

Lilacs are deciduous shrubs or small trees in the Oleaceae family. Grown widely for their fragrant flowers, over 500 cultivars of the common lilac have been developed. Neutral soils are the best to grow lilacs in, average watering but can withstand some drought once established. Flowers best in full sun, but will tolerate light shade. Lilacs are used as hedges, screens and back of border plantings. Prune after flowering so not to minimize the next year's flower display.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Edge of leaves cut in semicircle. Leafcutter bees (Megachile spp.).
Edge of leaves notched. Black vine weevil (Otiorhynchus sulcatus).
Leaves with blotchy mines. Lilac leafminer (Caloptilia syringella).
Leaves blacken and wilted. Bacterial brown spot (Pseudomonas syringaepv. syringae).
White powdery material on upper or lower surface of leaf. Powdery mildew (Microsphaera penicillata).
Leaves turn a rusty color. Rust Mites (eriophyid).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Scales. Oystershell scale (Lepidosaphes ulmi).
Borers. Lilac/ash borer (Podosesia syringae).
Maple

Maple

(Acer spp.)

Maples are deciduous trees or large shrubs in the Aceraceae family, and propagate by seeds, which have wings. The seeds fall, spinning toward the ground like a helicopter. Maple trees will vary in size by species, some reaching only fifteen to twenty feet, while other can grow to seventy feet or more in height. Maple trees have inconspicuous clusters of green flowers at the end of the young shoots. All maple trees have three principal veins radiating from the base of the leaf. The leaves vary in size by species; some reaching only an inch or so across, while others can be as large as six or more inches. Maple trees have many uses. The wood of maple trees is excellent as a source of fuel, and can be made into high quality charcoal. The wood is most often used for its ornamental quality. Furniture is often made from the sturdy, fine-grained wood. Maple trees have a sap that can be made into sugar easily. Their great canopy of leaves calls for a steady, constant supply of water.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed. Fruittree leafroller (Archips argyrospila).
White flecks on leaves. Leafhopper (Erythroneura spp.).
Black to brown spots on leaves. Anthracnose (Kabatiella sp.) or Septoria leaf spot and canker (Septoria sp.) or Tar spot (Rhytisma sp.).
Patches of reddish hairs (Rocky Mountain maple). Eriophyid mites.
Sucking insects on leaves, often honeydew. Boxelder and maple aphids (Periphyllusspp.) or Cottony maple scale (nymphs) (Pulvinaria innumerabilis).
Leaves yellowed (particularly silver maple). Iron chlorosis.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twigs with row of irregularly shredded punctures. Cicada injury (Platypedia putnami).
Large cottony insect on twigs. Cottony maple scale (Pulvinaria innumerabilis).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood and slime flux.
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) in the bark. Cytospora canker (Valsa spp.,Leucostoma spp.).
Large dead and discolored areas on southwest side of trunk. Winter sunscald.
Borers. Flatheaded appletree borer(Chrysobothris femorata).
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).
Mountain Ash

Mountain Ash

(Sorbus spp.)

Mountain ash, a member of the Rosaceae family, known for its fern-like foliage, clusters of white flowers and bright orange-red fruit. Most species are trees ranging from 20-60' tall. Mountain ash grow in average well-drained soils, pH adaptable, and hardy from zones 3 to 7. Most species make good lawn trees since the birds love the fruit. There are several tall shrub species(13') native to Montana, scopulina and sitchensis, which are found near moist areas and forest openings.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, raised pouches. Eriophyid mites.
Orange spots. Juniper rusts (Gymnosporangium spp.).
Rusty scabs on leaf. Blister mite. See Eriophyid mites.(Phytoptus spp.).
Chewing leaves. Pearslug (Caliroa cerasi).
Aphids. Apple aphid (Aphis pomi).
Blackened and wilting leaves. Fireblight (Erwinia amylovora).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Aphids. Wooly aphids (Eriosoma sp.).
Scales. Oystershell scale (Lepidosaphes ulmi) or Mealybug (Phenacoccus spp.).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Blackened, wilting, and crooked tips. Fireblight (Erwinia amylovora).
Discolored areas and dead bark containing small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Luecostoma spp.).
Large dead and discolored areas on southwest side of trunk. Winter sunscald.
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood and slime flux.
Borers. Flaheaded appletree borer (Chrysobothris femorata).
Oak

Oak

(Quercus spp.)

Oaks are decidious trees in the Fagaceae family known for their fruit (acorns) and wood. The wood is tough, durable, and attractively grained; it is especially valued in shipbuilding and construction and for flooring, furniture, tool handles, barrels and veneer. There are more than 80 species in North America, which are popular urban trees that tolerate a wde range of soil conditions. In Montana, bur oak is one of easiest to grow and tolerates more adverse conditions. Oaks have spirally arranged leaves with lobed margins in many species; some have serrated leaves or entire leaves with smooth margins. Many species do not drop dead leaves until spring. The bark of some oaks has been used in medicine, in tanning, and for dyes.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves tied together with silk, chewed. Oak leafroller (Archips semiferana).
Black/brown spotting on leaves. Anthracnose (Apiognomonia quercina).
Frothy mass on leaf vein. Spittlebugs (Clastoptera spp.).
Insects sucking on leaves. Spider mites (Oligonychus platani).
Small balls on leaves. Gall wasps (Cynipidae spp.).
Cottony growth on leaves, near midrib. Gall wasps (Cynipidae spp.).
Pale green or yellow leaves. Iron chlorosis.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twigs shredded by multiple punctures. Cicada oviposition injury (Platypedia putnami).
Witches' brooms on Gambel oak. Oak witches' broom (Articularia quercina).
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) in the bark. Cytospora canker (Valsa spp.,Leucostoma spp.).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood / slime flux.
Stem decay and/or hoof-shaped fruiting bodies (conks) on Gambel oak. White trunk rot of oak (Phellinus everhartii).

Affecting Fruit:

Signs/Symptoms Cause
Grubs feeding in acorn. Acorn weevils (Carculio spp.).
Onion

Onion

(Allium cepa)

Onions have many shapes, colors, and tastes of onions as there are uses for them in the kitchen: tender spring onions, red, yellow and white storage standbys, bunching onions, and gourmet shallots. Onions are a hardy, cool season plant that grows over a wide range of temperatures. Northern areas need cultivars that form bulbs under longer day conditions. Best growth occurs at temperatures of 55-75° F, in fertile, well drained soils high in organic matter. Onions are shallow rooted and need regular irrigation. You can plant seeds, sets or field grown transplants.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow leaves, slow growth. Nitrogen deficiency.
Yellow leaves, dwarfed plants. Aphids.
Brown leaf tips; white blotches on leaves. Onion thrips.
Tips of leaves die, pale green to brown leaf spots; later leaves are black with a purple, furry mold. Downy mildew (Peronospora effusa).
Leaf tips turn brown and die. Hot, dry weather and/or excessive heat.
Pale, green-silvery leaf spots. Can be a reaction to excessive rain or hail.
Papery, white leaf spots with a characteristic lengthwise split; brown leaf tips. Botrytis leaf blight.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Seedlings develop weak, water-soaked stems and fall over. Damping-off.
Wilted, yellow plants. Wireworm.
Yellow, wilting plants. Fusarium yellows (Fusarium oxysporum).
Yellow, dying plants. Onion or seedcorn maggot.
Parsnip

Parsnip

(Pastinaca sativa)

Parsnips are grown for their delicate-tasting roots, which can grow up to 15" long and 3-4" across at the top. They growing culture is much like a carrot except parsnips require less fertilizer and a higher pH (6.0-6.8). Optimum growing temperatures are 60-64°F, but will tolerate temperatures as low as 35-40°F. Parsnips are mature about 4 months after planting, ready for harvest in the fall, or if left in the ground thru winter if heavily mulched the flavor will be enhanced.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, dwarfed young leaves, bushy growth. Carrot yellows.
Yellow leaves, older first; stunted plants. Nitrogen deficiency.
Yellow, curled leaves. Aphids.
Dark spots with yellow borders. Cercospora leaf blight (Cercospora spp.) if younger leaves are affected. Alternaria leaf blight (Alternaria spp.)if older leaves are affected.

Affecting Roots:

Signs/Symptoms Cause
Yellow, stunted plants that wilt during bright, hot days and recover at night. Root injury. Check for Wireworms or Root-knot nematodes (Meloidogyne spp.).
Dark tunnels, often in a zig-zag pattern, on upper and outer part of root. Carrot weevil (Otiorynchus spp.).
Dark cankers on roots, root deterioration. Brown canker.
Rotted roots. Crop rotation needed or soil worked when wet.
Pea

Pea

(Pisum santivum)

Peas are a cool-season moisture-loving crop, grown to utilize the whole edible pod or just the green peas. Optimum growing temperatures are 60-75° F. All peas grow on vines, most types needing support to grow on. Low-nitrogen fertilizer is used with peas because they, like other legumes, draw nitrogen from the atmosphere with the help of soil bacteria. Peas prefer a pH of 5.5-6.8 and lighter soils with good organic matter.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, curling leaf margins, wilted plants; flowers and pods drop. Potato leaf hoppers.
Yellow, distorted new growth. Tarnished plant bug (Lygus pratensis).
Yellow leaves, slow growth. Nitrogen deficiency.
Yellow, withered, thickened and curled leaves; flowers may drop. Pea aphids.
Yellow crinkled, mottled, curled leaves. Mosaic virus.
Mottled, yellow, crumpled leaves; rosetting. Pea enation virus.
Yellow leaves, stems yellow inside; dwarfing and wilting. Fusarium wilt (Fusarium oxysporum).
Velvety, white growth on leaves. Downy Mildew (Peronospora effusa).
Powdery, white leaf spots. Powdery mildew.
White stippled leaves which later become bronzed.
White or translucent, irregular tunnels in leaves. Leafminers.
Leaf holes on young plants. Striped and spotted Cucumber beetles(Acalymma vittata).
Large holes in leaves. Army Cutworms (Euxoa auxiliaris).

Affecting Seeds, Seedlings or Roots:

Signs/Symptoms Cause
Seedlings clipped off at soil line. Cutworms (Noctuidae spp.).
Stems rot near soil line and plant collapses; seeds do not germinate. Damping off.
Poor germination, damaged seedling stem; deformed, spindly seedlings. Seed corn maggots.
Brown spot or cavity on seeds. Manganese deficiency.
White, powdery spots on pods. Powdery mildew.
Holes in blossoms, tunnels in seeds. Pea weevil adults.

Affecting Fruit:

Signs/Symptoms Cause
Blossoms drop. Excessive heat or rain.
Blossoms drop or pods fail to develop. Copper and/or molybdenum deficiency.
Pear

Pear

(Pyrus spp.)

Deciduous fruit trees in the Rosaceae family, with leathery, glossy bright green leaves and clusters of white flowers in the spring. Pears are of the oldest cultivated fruits in the world dating back over 5,000 years to Chinese farmers. Pear trees are of medium size typically reaching 15-30 feet tall and 10-20 feet wide. Most varieties require a partner for cross-pollination however some do not. There are over 3000 varieties, but only approximately 10 varieties in commercial production. The Bartlett variety comprises over 75% of the United States pear crop. Other European pear varieties include d'Anjou, Bosc, Comice, Seckel, and Winter Nelis. The European pear is noted for its soft, juicy flesh. The skin color is medium green to yellow, depending on fruit maturity and the variety. Skin texture can be smooth or rough. Fruit shape ranges from the classic pear shape (round base with narrow neck) to a rounded oblong shape with no clearly defined neck area.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Large holes chewed in leaves. Redhumped caterpillar (Schizura concinna) , or Forest tent caterpillar(Malacosma disstria ).
Silken tents produced. Western tent caterpillar or Fall webworm(Hyphantria cunea).
Caterpillar living within a case. Snailcase bagworm (Apterona helix ).
Terminal leaves curled and tied together with silk. Fruittree leafroller or Obliquebanded leafroller.
Skeletonized leaves. Apple and thorn skeletonizer (Choreutis pariana) or Apple flea beetle (Phyllotretaspp.).
"Shothole" feeding wounds in leaf, usually with sucker growth. Apple flea beetle (Phyllotreta spp.).
Raised leafmines. Western tentiform leafminer.
White powdery material on upper or lower surface of leaf. Powdery mildew.
Pale green or yellow leaves. Iron chlorosis.
Rust orange spots. Juniper rusts.
Black mold on surface of leaf. Apple scab (Venturia inaequalis).
Rusty blisters or scabby patches on leaves. Blister mites. See Eriophyid mites..
Bronzing of leaves. Two-spotted spidermite or McDaniel spider mite.
Curling distortions of new growth in spring. Rose apple aphids.
Blackened and wilted leaves. Fireblight (Erwinia amylovora).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twigs shredded by a line of multiple punctures. Cicada oviposition wounds.
Blackened, wilting, and crooked tips. Fireblight (Erwinia amylovora).
Black beetle tunneling, with small exit holes. Shothole borer.
Scales on twigs. Oystershell scale or European fruit lecanium.
Cottony insects on twigs. Woolly apple aphid or Mealybugs.
Discolored areas, dead bark containing small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Boring into trunk. Flatheaded appletree borer(Chrysobothris mali).
Bark beetle tunneling, small exit holes. Shothole borer.
ottony insects on trunk and/or roots. Woolly apple aphid.
Internal decay and/or shelf-like fruiting structures (conks). Decay fungus.
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).

Affecting Fruit:

Signs/Symptoms Cause
Tunneling in fruit. Codling moth (Cydia pomonella).
Scaring or sabbing of fruit. Fruittree leafroller, hail injury, or Apple scab (Venturia inaequalis).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
Discolored tissue under bark at ground line. Phytophthora root rot (Phytophthoraspp.).
Galls at ground line. Crown gall.

Affecting Roots:

Signs/Symptoms Cause
White root decay and white mycelial fans between bark and wood. Armillaria root disease (Armillaria spp.) .
Pepper

Pepper

(Capsicum annuum)

Sweet pepper, also called bell pepper and hot peppers are warm-weather shrubs from the tropics. The plants usually grow about 2" tall and wide. The fruit of sweet peppers grow 3-4" long and 2-3" wide; they can be harvested green (immature) or if allowed to ripen they turn yellow, orange or red. Hot peppers vary greatly in size and shape, all have a pungent flavor. Peppers are started indoors 6-8 weeks before the minimum night temperatures are above 55°F. Peppers need full sun and warm growing conditions to be productive.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Small, yellow-green spots, turning brown with lighter centers; near leaf margins first. Bacterial spot (Xanthomonas campestris).
Mottled, yellow, curled, thick and leathery leaves. Mosaic virus.
Yellow leaves wilt and curl; shiny and sticky leaves. Aphids.
Small holes chewed in leaves. Flea beetles (Phyllotreta spp.).
ircular, dark spots on leaves. Alternaria Leaf Blight.
New growth small, discolored, or deformed. Curly top.

Affecting Fruit:

Signs/Symptoms Cause
lants have blossoms, but no peppers. Extreme heat or cold.
Fruit blossoms drop prematurely; fruit is misshapen and discolored. Low temperature during blossoming and/or uneven growing conditions.
White or tan-colored, sunken, spots near tips of fruit; most often on earliest fruit during dry periods; up to 1/3 of the fruit may become dark and shriveled. Blossom end rot.
Sunken, white papery-looking areas on side of fruit exposed to the sun. Sunscald.
Small, dark brown, wartlike spots on fruit; most prevalent during damp weather. Bacterial spot (Xanthomonas campestris).
Large, yellow to dark brown spots on ripe peppers, followed by rotting; spots have black-specked centers. Anthracnose.
Feeding at seed core with hole near stem end of pepper; sawdusty excrement is usually visible at stem end; peppers often rot and color early. European corn borer (Ostrinia nubilalis).
Pine

Pine

(Pinus spp.)

Pines are evergreen trees and shrubs with over 90 species in the northern hemisphere. Their number of needles in a bundle and size and shape of cones are the characteristics by which pines are classified. The pines are of primary importance in the production of timber, pulp and paper production. Turpentine, pine-wood oils, wood tars, and rosin are obtained from the wood of several species. The leaf oils of several species are used in the manufacture of medicines and the seeds of several others are suitable for food (pine nuts). Generally pines are more tolerant of adverse soil and climatic conditions than spruce and firs. Most pines are pyramidal in shape, but some can be pruned into hedges and screens.

Additional Information

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Galls on small branches that turn bright orange/yellow in spring. Western gall rust (Endocronartium harknessii).
Swollen and/or twisted terminal growth. Herbicide injury. See Chemical Injury.

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Tunnels oozing popcorn-like white pitch, often near crotches. Pine moth (Dioryctria spp.).
Galls on large branches or trunk. Western gall rust (Endocronartium harknessii).
Cankers, with resin and squirrel chewing. Comandra rust [in lodgepole pine] - (Cronartium comandrae).
Roughened bark and resin production. White pine blister rust (on five needle pines).
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (various species).
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (various species).
Regular row of holes. Woodpeckers.
Bark beetles. Engraver beetles (Ips spp.), Mountain pine beetles (Dendroctonus ponderosae), or Red turpentine beetle (Dendroctonus valens LeConte).
Small shoots emerging from the branch.

Affecting Roots:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease (Armillaria mellea).

Affecting Needles:

Signs/Symptoms Cause
Mottled yellowing of needles on a branch. Winter exposure injury.
Needles to exterior of tree bleached or brown, developing late winter. Winter dessication.
Discoloration, needle drop of current or previous year's growth. Needle casts (Bifusella sp.,Davisomycella sp., Elytoderma deormans, Lophodermella sp.,Lophoedermium sp.); or Giant conifer aphids (Cinara spp.).
Brown felt-like material on needles (high elevations). Brown felt blight (Neopeckia coulteri).
Needles twisted, stunted. Eriophyid mites (Trisecatus spp.).
Aphids on needles. Giant conifer aphids (Cinnara spp.).
Scales on needles. Pine needle scale (Chionaspis pinifoliae).
Whole tree fades, reddens. Mountain pine beetle (Dendroctonus ponderosae Hopkins).

Affecting Cones:

Signs/Symptoms Cause
Cones tunneled by caterpillars. Coneworms (Dioryctria spp.).
Sucking on developing cones. Conifer Seed Bugs.
Potato

Potato

(Solanum tuberosum)

The potato is a starchy, tuberous crop that was introduced outside the Andes region four centuries ago, and have become an integral part of much of the world's cuisine. It is the world's fourth-largest food crop, following rice, wheat and maize. Potato cultivars appear in a huge variety of colors, shapes, and sizes. Potatoes require a loose, well-drained soil and plenty of sun. Potatoes are sensitive to fluctuating soil moisture levels; if irrigation is not well distributed throughout the season, growth cracks and knobby tubers will result. Potatoes are heavy feeders and require moderate to high levels of nitrogen, phosphorus, potassium, calcium and sulfur. Plant certified seed when soil temperatures reach 40°F.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Large gray-brown spots with concentric rings; spots merge and cover entire leaf. Early blight (Alternaria spp.).
Water-soaked brown lesions on lower leaves first. Late blight.
Light-green to yellow leaves with lower leaflets rolled upwards. Leaf roll virus.
Yellow, mottled leaves accompanied by crinkling. Mosaic virus.
Yellow leaves, stem black below soil line. Blackleg (Erwinia caratova).
Yellow, puckered, curled leaves. Potato aphids.
Yellow, stippled, stunted leaves. Leafhoppers.
Holes in leaves are large; whole leaflets consumed. Colorado potato beetle (Leptinotarsa decemlineata).
Small holes in leaves. Flea beetles (Phyllotreta spp.).

Affecting Tubers:

Signs/Symptoms Cause
Brown to black raised spots on potato. Rhizoctonia (Rhizoctonia spp.).
Rough, raised lesions on potato. Potato scab.
Enlarging brown to black blotches on potato; internal tissue is brown and dry just below the surface. Early blight (Alternaria spp.).
Tiny surface trails (or tunnels) just beneath potato skin. Tuber flea beetle larvae (Phyllotretaspp.).
Dark, internal lesions on potatoes. Phosphorus or potassium deficiency.
Dwarfed potatoes. Calcium deficiency.
Green coloration of tubers. Exposure to light. Keep developing tubers covered with soil.
Privet

Privet

(Ligustrum spp.)

Privets are deciduous shrubs that are most widely used as hedges. Privets all have clusters of white flowers in the spring followed by clusters of black fruit. Privets are easily grown in most soils and prefer full sun to light shade. Depending on species privets height range from 4-15'.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Edge of leaves cut in semicircle. Leafcutter bees (Megachile spp.).
Edge of leaves notched. Black vine weevil (Otiorhynchus sulcatus).
Leaves with blotchy mines. Lilac leafminer (Caloptilia syringella).
Leaves blackened and wilted. Bacterial blight (Pseudomonas syringaepv. syringae).
White powdery material on upper or lower surface of leaf. Powdery mildew (Microsphaera penicillata).
Leaves turn a rusty color. Rust mites.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Scales. Oystershell scale (Lepidosaphes ulmi).
Borers. Lilac/ash borer (Podosesia syringae).
Pyracantha

Pyracantha

(Pyracantha spp.)

Pyracantha is an evergreen to semi-evergreen shrub in the Rosaceae family grown for their glossy green leaves and bright fruit. Pyracantha grows fast with a upright to sprawling habit. The thorny branches need regular pruning to keep them in good shape. Used in the landscape as a hedge, topiary shape or ground cover. Plant in full sun to part shade in well-drained soils.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Stippling of leaves. Spider mites (Tetranychidae spp.).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twig blight/dieback. Fireblight (Erwinia amylovora).
Rabbitbrush

Rabbitbrush

(Chrysothamnus spp.)

Rabbit-brush are shrubs whose flexable branches are covered with felt-like hairiness. Rabbit-brush grows in dry open habitats in the valleys and foothills. Shrubs range in height from 3-5'. Clusters of yellow flowers appear in the late summer or fall. American Indians used rabbit-brush to make chewing gum, tea, cough syrup, and yellow dye. The rubbery twigs were used in making baskets.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed. Snailcase bagworm (Apterona helix).
White powdery material on upper or lower surface of leaf. Powdery mildew.
Orange pustules on leaf. Leaf rust.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Frothy mass on stems. Spittlebug (Clastoptera spp.).
Cottony balls on stems. Rabbitbrush gall flies (Aciurina bigeloviae).
Green flowerlike swellings. Rabbitbrush gall flies (Aciurina bigeloviae).
Radish

Radish

(Raphanus sativus)

There are two main types of radishes - the regular small and quick maturing and the winter ones which are larger and more pungent. Most commercial varieties are red but radishes can be white, red & white and purple-black. Radishes like cool, moist growing conditions. They can germinate and grow at 40°F, but optimum temperatures are 50-65°F. Water heavily for the first two weeks after emergence.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow v-shaped spots on leaf margins with blackened veins. Black rot (Xanthomonas campestris).
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems; usually occurs soon after transplanting. Fusarium yellows (Fusarium oxysporum).
Yellow leaves, older first; stunted plants. Nitrogen deficiency.
Yellow, curled leaves; stunted plants. Aphids.
Purplish patches on leaves. Phosphorus deficiency in cool soils.
Small leaf holes. Flea beetles (Phyllotreta spp.).
Large leaf holes. Cabbage Loopers or Imported Cabbage Worms (Pieris rapae).

Affecting Roots:

Signs/Symptoms Cause
Yellow, stunted plants that wilt during bright, hot days and recover at night. Root injury. Check for root maggots.
Small, imperfectly formed roots. Nitrogen deficiency.
Poor root development. Phosphorus deficiency.
White spots or streaks internally; large air spaces and tough, dry roots. High temperature injury.
Soft, shriveled roots. Freezing injury.
Raspberry

Raspberry

(Rubus spp.)

Raspberries are easy to grow shrubs with biennial canes. The canes that have fruit on them in the second year then die with new canes sprouting up to take their place. Raspberries can be red, yellow or black in color. There are everbearing which fruit ripens on 2 year canes in summer and on the top of new first year canes in the fall, and the summerbearing which ripen early to midsummer on the second year canes. Raspberries need full sun and a well-drained soil with lots of organic matter in it.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
New leaves and shoots have a powdery appearance. Later, light brown to orange pinhead-sized balls form within the mass of white growth. These tiny dots mature and turn a black color. These black structures are the overwintering stage. Powdery mildew.
Leaves on infected plants are uniformly small, dark green, crinkled, and tightly curled downward and inward. When diseased shoots first appear, they are pale yellowish-green, but they soon turn dark green, become stiff and brittle, and usually do not branch.Plant lose vigor each year. Berries on infected plants may ripen prematurely and are small, dry, seedy, and crumbly. Raspberry Leaf Curl Virus. Infected plants should be destroyed immediately.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Larvae bore many tunnels in canes and the crown may be extensively damaged. Raspberry crown borer.

Affecting Fruit:

Signs/Symptoms Cause
Worm Like grubs inside raspberries Prune out old canes as soon as they fruit and cultivate around plants The adults cause characteristic slits in the leaves from their feeding and destroy developing buds. The larvae feed within the blossoms and inside developing fruit. Western Raspberry Fruitworm.

Affecting Roots and Ground Line Area:

Signs/Symptoms Cause
The most obvious symptoms of root rot are stunted, yellowing leaves, premature fall coloration and leaf drop, and twig and branch dieback. By the time the foliar symptoms develop, the rot canker may extend halfway or more around the stem of the plant. In early stages, the diseased bark is firm and intact while the inner bark is slimy and may produce a moist, gummy exudate. Phytophthera Root Rot.
Rhubarb

Rhubarb

(Rheum rhaponticum)

Rhubarb is a hardy perennial grown for its red and green stemmed stalks. The stalks are topped with dark green leaves that are poisonous. Rhubarb prefers a pH of 6-6.8 and a deep, sandy, well drained soil high in organic matter. Mulch with several inches of high nitrogen compost each spring and water the mulch down well. Do not over harvest, so the plant will not be stressed. Harvest rhubarb by grasping each stalk near its base and giving it a sideward twisting tug. Canada red and honeyred are good red stalk varieties.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, curling leaf margins, wilted plants. Leafhoppers
Yellow leaves, slow growth. Nitrogen deficiency.
Wilting, yellow leaves, marginal leaf browning. Verticillium wilt (Verticillium spp.).
Small, round, brown spots on leaves. Fungal disease.

Affecting Stalks:

Signs/Symptoms Cause
Holes chewed in stalks. Worms, including European corn borer(Ostrinia nubilalis) and Imported Cabbage worm(Pieris rapae).
Rose

Rose

(Rosa spp.)

A rose is a woody perennial of the genus Rosa, within the family Rosaceae. There are over 100 species. They form a group of plants that can be erect shrubs, climbing or trailing with stems that are often armed with sharp prickles. Flowers vary in size and shape and are usually large and showy, in colors ranging from white through yellows and reds. Most species are native to Asia, with smaller numbers native to Europe, North America, and northwest Africa. Species, cultivars and hybrids are all widely grown for their beauty and often are fragrant. Rose plants range in size from compact, miniature roses, to climbers that can reach 20 feet in height. Different species hybridize easily, and this has been used in the development of the wide range of garden roses.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
White powdery material on upper or lower surface of leaf. Powdery mildew (Sphaerotheca pannosa).
Leaves with white spotting. Rose leafhopper (Edwardsiana rosae) orTwospotted spider mite (Tetranychus urticae Koch) or Rust (Phragmidium mucronatum).
Small ball-like growths on leaves, usually reddish. Gall wasps.
Leaves mottled with yellowish areas. Iron chlorisis or Rose mosaic complex(various viruses are responsible).
Orange-red colored patches on lower leaf surface. Rose rust.
Angular brown spots on leaves. Anthracnose.
Interior areas of leaves chewed. Roseslug and other sawflies (Endelomyia aethiops).
Even, semicircular cuts in leaf edge. Leafcutter bees (Megachile spp.).
Leaves curled. Powdery mildew or Aphids.
Dark spots on leaves. Black spot (Diplocarpon rosae).

Affecting Flowers:

Signs/Symptoms Cause
Flower buds killed, fail to emerge (blind shoots). Rose midge (Dasineura rhodophaga); Fluctuating, cool temperatures; or Rose curculio (Merhynchites bicolor).
Flower petals scarred. Flower thrips (Thysanoptera spp.).
Flower petals chewed or tunneled. Earwigs (Forficula auricularia L.), Rose curculio (Merhynchites bicolor).
Flowers produced are off-type after winter (Grandiflora and hybrid tea roses). Die back to the grafted rootstock.

Affecting Canes:

Signs/Symptoms Cause
Insects tunneling into pith of cane. Leafcutter bees (Megachile spp.).
Exterior area of cane girdled, sometimes with associated dieback. Bronze cane borer / Rose stem girdler(Agrilus aurichalc).
Mossy or ball-like growths on stem. Gall wasps (Diplolepsis sp.).
Woody, tumor-like growth, usually on lower stem. Crown gall (Agrobacterium tumefaceins).
Swellings in canes, often with associated vertical cracking. Bronze cane borer / Rose stem girdler(Agrilus aurichalceus).
Purple to tan, sometimes sunken spots on canes. Rose canker (Cryptosporella orLeptosphaeria sp.).
Serviceberry

Serviceberry

(Amelanchier spp.)

Serviceberry are deciduous shrubs or small trees also called juneberry or saskatoons. They produce drooping clusters of white flowers in early spring which form dark blue fruits, popular with birds. Serviceberry grows best in full sun to part shade and is tolerant of many soils as well as they are well drained.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Orange leaf spots, defoliation and fruit and twig deformities. Cedar apple rust.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twigs in short thick clumps. Witches broom (Apiosporina collinsii).
Spinach

Spinach

(Spinacia oleracea)

Spinach is a cool season crop that can be grown in the spring and fall and overwintered. There are two different leaf forms crinkled (savoy) and flat leaf. Spinach prefers temperatures of 60-65°F and is unhappy when temperatures reach 75° which causes them to bolt (form seed heads). Soils with good drainage and high organic matter are preferred. Spinach is a heavy nitrogen feeder with moderate levels of phosphorus and potassium required.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow area on leaf upper surface with blue-gray patches on undersides of leaves. Downy mildew (Peronospora effusa).
Young center leaves turn yellow and curl, followed by mottling, browning, and death of larger leaves. Tobacco Mosaic Virus.
Yellow deformed leaves that eventually die, along with stunted plants. Curly-top.
Yellow curled leaves and stunted growth. Aphids, usually green peach aphids.
Light-colored winding tunnels in leaves; becomes an enlarged blotch at the ends of leaves which may turn white or brown. Spinach leaf miner.
Small holes in leaves, undersides of leaves may be skeletonized. Flea beetles (Phyllotreta spp.).
Ragged holes in outer leaves, usually between leaf veins. Cabbage looper and/or Beet armyworm.
Spirea

Spirea

(Spiraea spp.)

Spirea are deciduous shrubs that come in various shapes and sizes with flower colors of pink, red and white. Easy to grow in all kinds of soils, in sun or light shade, and average water. Form, height, leaf color and flowering season vary between varieties. Spirea has very few pests attacking it including deer.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Insect on leaves, sometimes associated with leaf curls. Spirea aphid (Aphis citricola).
Spruce

Spruce

(Picea spp.)

Spruce are evergreen trees and shrubs that have many varieties of shapes and sizes. They are large pyramidal or cone shaped trees or dwarf forms that are useful in foundation plantings, rock gardens and containers. Spruce are used extensively in large scale landscape plantings such as parks, golf courses, highways, and public buildings. Spruce have a shallow, spreading root system allowing them to be transplanted as a large specimen easily. They prefer a moderately moist well-drained soil but can adapt to clay soils as well. Spruce trees are used for pulp and paper manufacturing as well as their pitch being used as a compound for varnishes and medicinal compounds.

Additional Information

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Twigs distorted into cone-like gall. Cooley spruce gall adelgid (Adelges cooleyi).
Woolly aphid on underside of twigs in spring. Cooley spruce gall adelgid (Adelges cooleyi).
Small bud-like scales on twigs. Spruce bud scale.
Large aphids on branch. Giant conifer aphids (Cinara spp.).
Resinous canker on branch. Cytospora canker (Valsa spp.,Leucostoma spp.).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Bark beetles. Spruce beetle (Dendroctonus rufipennis) or Spruce ips (Ips hunteri Swaine).
Aphids. Giant conifer aphids (Cinara spp.).
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (Phellinus pini,Inonotus circinatus, Fomitopsis pinocolaand various fungal genera).
Fungal fruiting bodies (mushrooms, conks) present. Stem decay fungi (Phellinus pini,Inonotus circinatus, Fomitopsis pinocolaand various fungal genera).

Affecting Roots:

Signs/Symptoms Cause
White root decay with white mycelial fans between bark and wood. Armillaria root disease (Armillaria mellea).

Affecting Needles:

Signs/Symptoms Cause
New needles being chewed. Douglas-fir tussock moth (Orgyia pseudotsugata) or Western spruce budworm (Choristoneura occidentalis).
Needles chewed and fragments tied with webbing. Spruce needleminer (Endothernia albolineana).
Brown felt-like material on needles, branches (high elevation). Brown felt blight (Herpotrichia juniperi) or Snow mold.
Needles being mined. Spruce needleminer (Endothenia albolineana).
Aphids on needles. Giant conifer aphids (Cinara spp.).
Needles become grayish, with small flecks. Spruce spider mite (Oligonychus ununguis).
White scales on needles. Pine needle scale (Chionaspis pinifoliae).
Brown needles with dark fruiting bodies. Needlecasts (Lophodermium sp. and others).
Needles to exterior of tree bleached or brown, developing late winter. Winter desiccation.
Needles on branch turn reddish brown. Cytospora canker (Valsa spp.,Leucostoma spp.) or Root injury.
Mottled yellowing of needles on a branch. Winter exposure injury.

Affecting Top of Tree:

Signs/Symptoms Cause
Wilting and dieback restricted to terminal, shepherds' crook. White pine weevil (Pissodes strobi).
Upper crown defoliated. Douglas-fir tussock moth (Orgyia pseudotsugata).
Upper crown dieback. Spruce ips (Ips hunteri Swaine).
Squash

Squash

(Cucurbita spp.)

There are four species of squash which are divided into summer and winter types in more shapes and colors than most gardeners will ever have the room to grow. Summer squashes are eaten in immature stages while winter squashes are utilized when fruits are mature. Squash insist upon full sun and warm temperatures >60°F. Squash prefer well-drained soils with lots of organic matter. Keep squash well watered as they have a very shallow root system supporting a large mass of leaves. Each squash produces both male and female flowers separately on the same plant, so pollination is essential for good production.

Additional Information

Affecting Fruit:

Signs/Symptoms Cause
Small, brown, angular fruit spots. Angular leafspot (Pseudomonas syringae).
Brown and sunken zoned spots. Alternaria (Alternaria spp.).
Circular, black, sunken cankers. Anthracnose.
Misshapen, yellow mottled fruit, often with a bitter taste. Mosaic virus.
Fruit wilts and shrivels. Bacterial wilt (Erwinia tracheiphila).
Fruit is narrow at stem end. Potassium deficiency.
Fruit has a dull bronze color. Phosphorus deficiency.
Fruit is light colored. Nitrogen deficiency.
Dark pitting of fruit. Cold damage.

Affecting Leaves and Vines:

Signs/Symptoms Cause
Plants wilt, foliage looks burned; preceded by pale green areas forming on leaves. Squash bug (Anasa tristus).
Sudden wilting of a runner or part of a runner. Squash vine borer (Melitta satyriniformis).
Leaves wilt, yellow, and curl. High aphid populations.
Vines wilt and die gradually, starting with newer leaves; no leaf yellowing is present. Bacterial wilt (Erwinia tracheiphila).
Small, pitted leaf holes on young plants. Cucumber beetles (Acalymma vittata).
Distorted, Yellow spots on leaves with mottling and wrinkling of older leaves. Mosaic viruses.
Older leaves mottled yellow between veins. Downy mildew (Peronospora effusa).
Powdery, white spots on upper surface of leaves especially. Powdery mildew.
Leaf spots that begin as water-soaked, then turn gray, die and drop out leaving foliage with a shot-hole appearance. Angular leafspot (Pseudomonas syringae).
If water-soaked, yellow spots turn brown. Anthracnose.
Leaves are yellow and puckered and become bronzed. Mites.
Dark brown spots with concentric rings on older leaves first; vines defoliate eventually. Alternaria leaf blight (Alternaria spp.).
Spots with pale, round centers and dark margins on upper surface of leaves. Cercospora leaf spot (Cercospora spp.).
Stone Fruits 2: Apricot, Cherry Chokecherry, Peach, Plum, etc.
Stone Fruits 2: Apricot, Cherry Chokecherry, Peach, Plum, etc.

Stone Fruits 2: Apricot, Cherry Chokecherry, Peach, Plum, etc.

(Malus spp.)

The genus Prunus is comprised of nearly 200 species of five subgenera: plums and apricots, almonds and peaches, umbellate cherries, deciduous racemose cherries, and the evergreen racemose cherries. The species of this genus range from shrubs to trees over 90 ft. tall. Over 100 species have been cultivated as either ornamentals or as food crops. Trees for fruit production and many ornamentals are generally propagate by budding or grafting, while seed propagation is reserved for generation of rootstocks and breeding programs. The most common rootstock:scion combinations are: almond:almond and plum; apricot:apricot; mazzard cherry:sweet cherry; mahaleb cherry:sweet and sour cherry; peach:peach, almond, apricot, plum; American plum:plum in cold regions; Bessey cherry:dwarf peaches.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed, no associated webbing. Pearslug (Caliroa derasi).
Upper surface of the leaf skeletonized. Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer.
Webbing associated with chewing. Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum).
Leaves with small, circular holes. Shot hole disease.
White flecking injuries. White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.).
White powdery material on upper or lower surface of leaf. Powdery mildew.
Leaves yellow. Iron chlorosis or X-disease.
Leaves with small, pouch or finger-like projections. Fingergall mites (Phytoptus species).
New leaves curled. Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi).
New leaves curled and thickened and red/purple. Peach leaf-curl disease.

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Black galls on branches. Black knot of cherry (Apiosporina morbosa).
Stem decay and/or hoof-shaped fruiting body (conk). Decay fungus (Phellinus pomaceus).
Scales. Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi).
Small pinhead-sized exit holes in branches. Shothole borer (Scolytus rugulosus).
Branches die back. Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus).
Gumming and dark colored branches. Shothole borer (Scolytus rugulosus), orCytospora canker (Valsa spp.,Leucostoma spp.) orBacterial Blight (Pseudomonas syringae).
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).

Affecting Fruit:

Signs/Symptoms Cause
Fruit tunneled. European earwig (Forficula auricularia L.).
Fruit with sunken, corky areas. Plant bug (Lygus species), Hail injury, orBoxelder bug (Boisea trivittata).
Puncture wounds in fruit. Bird damage (Robins, finches, etc.).
Chokecherry fruit enlarged, hollow. Chokecherry gall midge (Contarinia virginianae).
Maggots in cherry fruit. Western cherry fruit fly (Rhagoletis indifferens Curran.

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
Discolored tissue under bark at ground line. Phytophthora root rot (Phytopthora sp.).
Gall at ground line. Crown gall (Agrobacterium tumefaciens).
Stone Fruits:  Apricot, Cherry Chokecherry, Peach, Plum, etc.

Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc.

(Prunus spp.)

The genus Prunus is comprised of nearly 200 species of five subgenera: plums and apricots, almonds and peaches, umbellate cherries, deciduous racemose cherries, and the evergreen racemose cherries. The species of this genus range from shrubs to trees over 90 ft. tall. Over 100 species have been cultivated as either ornamentals or as food crops. Trees for fruit production and many ornamentals are generally propagate by budding or grafting, while seed propagation is reserved for generation of rootstocks and breeding programs. The most common rootstock:scion combinations are: almond:almond and plum; apricot:apricot; mazzard cherry:sweet cherry; mahaleb cherry:sweet and sour cherry; peach:peach, almond, apricot, plum; American plum:plum in cold regions; Bessey cherry:dwarf peaches.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed, no associated webbing. Pearslug (Caliroa derasi).
Upper surface of the leaf skeletonized. Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer.
Webbing associated with chewing. Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum).
Leaves with small, circular holes. Shot hole disease.
White flecking injuries. White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.).
White powdery material on upper or lower surface of leaf. Powdery mildew.
Leaves yellow. Iron chlorosis or X-disease.
Leaves with small, pouch or finger-like projections Fingergall mites (Phytoptus species).
New leaves curled. Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi)
New leaves curled and thickened and red/purple. Peach leaf-curl disease.

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Black galls on branches. Black knot of cherry (Apiosporina morbosa).
Stem decay and/or hoof-shaped fruiting body (conk). Decay fungus (Phellinus pomaceus).
Scales. Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi).
Small pinhead-sized exit holes in branches. Shothole borer (Scolytus rugulosus).
Branches die back. Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus).
Gumming and dark colored branches. Shothole borer (Scolytus rugulosus), or Cytospora canker (Valsa spp.,Leucostoma spp.) or Bacterial Blight (Pseudomonas syringae).
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Wilting and dieback of portions of tree, originating from roots. Verticillium wilt (Verticillium spp.).

Affecting Fruit:

Signs/Symptoms Cause
Fruit tunneled. European earwig (Forficula auricularia L.).
Fruit with sunken, corky areas. Plant bug (Lygus species), Hail injury, or Boxelder bug (Boisea trivittata).
Puncture wounds in fruit. Bird damage (Robins, finches, etc.).
Chokecherry fruit enlarged, hollow. Chokecherry gall midge (Contarinia virginianae).
Maggots in cherry fruit. Western cherry fruit fly (Rhagoletis indifferens Curran).

Affecting Ground Line Area of Trunk:

Signs/Symptoms Cause
Discolored tissue under bark at ground line. Phytophthora root rot (Phytopthora sp.).
Gall at ground line. Crown gall (Agrobacterium tumefaciens).
Strawberry

Strawberry

(Fragaria spp.)

Strawberries, one of the easiest fruits to grow, in the ground, containers, or hanging baskets. There are many varieties in the three types: june-bearing - produces one crop per year, everbearing - produces two crops per season, day-neutral - produces all season long. June-bearing are the most common and thought to be the best tasting. Strawberries like full sun and well drained soils that are high in organic matter. The strawberry propagates itself by sending out runners (stolons) from buds in the plants crown which will root new plants. Most strawberry beds need to be renovated with new plants every 3 years to keep the planting in peak production.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Yellow, distorted leaves. Aster yellows virus.
Small, deep purple, round to elongate spots on leaves and sometimes on fruit. Spots enlarge and develop light-colored centers. Relative humidities of 98-100% and temperatures of 59 to 77º F promote infection. Middle-aged leaves appear to be most susceptible. Plant on raised beds and avoid sprinkler irrigation. Common leaf spot (Mycosphaerella fragariae).
Yellow stippled to bronzed-colored leaves. Spider mites.
White frothy areas on leaves and stems. Spittle bugs.

Affecting Fruit:

Signs/Symptoms Cause
Senescent leaves, fruits, and petals are susceptible. Under cool (60 - 70° F.), moist conditions a soft, brown decay develops, covered by a dense gray to light brown mass of spores. Gray Mold (Botrytis cenerea).
Sumac

Sumac

(Rhus spp.)

Sumacs are deciduous shrubs or small trees in our area. Sumacs are very hardy and thrive in poor soils. They tend to sucker and spread into large colonies if left unchecked. A large, loose spreading habit with many toothed leaflets that turn a brilliant scarlet/orange color in the fall. Several varieties common to the area such as staghorn which gets its name for the short brown hairs that covers the stems resembling deer's antlers in velvet.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Small reddish swellings. Eriophyid mite gall.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Dark insects on twigs. Oystershell scale (Lepidosaphes ulmi).
Discolored areas, dead bark containing small pinmple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Wilting and dieback of portions of plant originating from roots. Verticillium wilt (Verticillium spp.).
Sycamore

Sycamore

(Platanus spp.)

Sycamores are fast growing large trees with lobed maple-like leaves. Brown, ball like seed clusters hang from branches through the winter. Easily transplanted; prefers deep rich, moist, well-drained soils but will grow in about anything. Older bark sheds in patches to reveal pale, smooth, new bark beneath. Sycamores are good for large areas such as parks and open spaces, but not in small yards and along streets. The variety "bloodgood" has some resistance to anthracnose.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves with blackened spotting. Anthracnose (Apiognomonia veneta).

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Discolored areas, dead bark containing small pinmple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Witches' broom with dead small branches. Anthracnose (Apiognomonia veneta).

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Discolored areas, dead bark containing small pinmple-like fruiting bodies (pycnidia). Cytospora canker (Valsa spp.,Leucostoma spp.).
Clear to white oozing or frothy malodorous liquid. Bacterial wetwood / Slime flux.
Tomato

Tomato

(Lycopersicon esculentum)

One of the most popular grown garden plants, tomatoes will be prolific producers if given a warm, sunny location with rich, well drained soils. There are two main types to choose from. Determinant types grow to a certain height and stop, putting all their energy into producing fruit over a 4-6 week period. Indeterminant types continue to grow, producing new fruiting clusters all season long. Tomatoes grow best at temperatures of 65-95° F. There are many varieties such as paste, cherry, patio, slicing, hybrid, heirloom and many colors to choose from. Pick varieties suitable to your climate and growing season.

Additional Information

Affecting Fruit:

Signs/Symptoms Cause
Large chunks of green fruit consumed. Tobacco and tomato hornworm or Colorado potato beetle.
Small holes on fruit surface with a messy, watery, rotten internal cavity. Fruit appears to collapse like a balloon. Tomato fruitworm, also called Corn earworm.
Dark pinpricks surrounded by light areas; white, spongy area below spots. Stink bugs.
Scarring and malformation of fruit, especially at blossom end. Catfacing.
Yellow or white blister-like patch on fruit, usually on side exposed to the sun. Sunscald.
Yellow streaks or shoulders; uneven fruit ripening. Mosaic virus.
Fruit cracks at stem end radially or in concentric circles around shoulders. Cracking, due to uneven irrigation.
Black sunken area at blossom end of fruit; often seen in first ripening fruit; hard, dark area inside fruit. Blossom end rot.
Gray to brown blotches develop on the surface of green fruit with internal browning and uneven ripening. Graywall.
Sunken, dry spots with concentric rings near stem end. Early Blight.
Water-soaked spots, enlarging to large brown areas that remain firm. Late Blight.

Affecting Buds:

Signs/Symptoms Cause
Brown spots, distorted leaves and stems; stunted and sticky leaves covered with a black film. Aphids.

Affecting Leaves and Stem:

Signs/Symptoms Cause
Young leaves turn yellow between veins. Iron deficiency, usually on soils with high pH.
Younger leaves pale, terminal buds die. Calcium deficiency.
Leaves on young plant are purple. Phosphorus deficiency.
Older leaves pale, small, general yellowing. Nitrogen dificiency.
Older leaves turn yellow between veins while veins remain green, then become bronzed. Potassium deficiency.
Yellow, mottled leaves; curling and malformation giving terminals a fernlike appearance. Mosaic virus.
Black to brown angular to circular small spots (without concentric zones). Bacterial Spot.
Leathery, black-brown spots with concentric rings; lower leaves and stems affected first; occurs during humid/wet, warm conditions. Early Blight.
Black-green water soaked areas on older leaves, branches, and stems, usually in humid/wet cooler weather (60-70° F.). Late Blight.
Small to large round holes in leaves, plants and leaflets stripped. Colorado Potato Beetle.
Whole leaves consumed. Tobacco hornworms.
Small pitted holes, shot-hole injury. Flea beetles (Phyllotreta spp.).
Leaves have irregular chew holes giving the leaves a ragged appearance. Cabbage Looper.
Turf

Turf

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One of the most popular grown garden plants, tomatoes will be prolific producers if given a warm, sunny location with rich, well drained soils. There are two main types to choose from. Determinant types grow to a certain height and stop, putting all their energy into producing fruit over a 4-6 week period. Indeterminant types continue to grow, producing new fruiting clusters all season long. Tomatoes grow best at temperatures of 65-95° F. There are many varieties such as paste, cherry, patio, slicing, hybrid, heirloom and many colors to choose from. Pick varieties suitable to your climate and growing season.

Additional Information

Affecting Fungi:

Signs/Symptoms Cause
Dark green circular area more vigorous in growth with or without mushrooms bordered by a dead zone. Fairy Ring (Basidiomycetes).
Yellow lower leaves with reddish black round spots. Melting Out (Drechslera spp.).
White dust on grass blades; may eventually cover the entire blade, can cause yellowing and puckering Most often found in shady wet areas. Powdery Mildew (Erysiphe, Sphaerotheca, Phyllactinia, Microsphaera, Podosphaera, or Uncinula spp.).
Pinkish - red strands form at leaf tip in spring and fall on red fescues and Kentucky bluegrass. Red Thread (Laetisaria fuciformis).
Irregular, circular white to gray or pink spots on lawn. Visible when snow and ice recede. Snow Mold (Fusarium patch).
Winter watering may not be necessary for established lawns. However, lawns started within the last year may be susceptible to winter desiccation injury and need supplemental winter irrigation. Winter Desiccation.

Affecting Insect:

Signs/Symptoms Cause
Young leaf blades cut off at soil line, brown spots in lawn. Cutworms.
Weak turf, death in large patches Root pruning Damage seen in late summer. White Grubs.
Virginia Creeper

Virginia Creeper

((Parthenocissus quinquefolia))

Virginia creeper is a fast growing deciduous vine with tendrils that can cling to walls by the adhesive-like tips, cementing itself, therefore needing no support. Tolerates most types of soil in sun or shade. Excellent low maintenance cover for walls and ground cover for almost anything. Turns a brilliant red fall color. Birds are known to spread the seed and it can become a weedy pest.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves flecked with white spots and eventually brown, curled margins. Leafhoppers.
Willow

Willow

(Salix spp.)

Willows are deciduous shrubs or trees known for their fast growing nature. Willows grow in many soil types but need lots of water. All have very invasive roots which can be problems around foundations and drain fields. Some of the shrub types are noted for erosion control along stream banks.

Additional Information

Affecting Leaves:

Signs/Symptoms Cause
Leaves chewed. Spiny elm caterpillar (Nymphalis antiopa), Speckled green fruitworm (Orthosia hibisci), Western tent caterpillar (Malacossoma californicum),Fall webworm (Hyphantria cunea), or Willow leaf beetle (Chrysomela aeneicollis).
Masses of dark, spiny caterpillars on leaves. Spiny elm caterpillar (Nymphalis antiopa).
Leaves with black spotting. Tar spot (Rhytisma salicinium).
Rust to orange colored leaf spots. Willow leaf rust.
Leaves with irregular raised pouch galls. Eriophyid mite (Aculops tetanothrix).
Leaves skeletonized by beetle larvae. Cottonwood leaf beetle (Chrysomela scripta) or Willow leaf beetle (Chrysomela aeneicollis).
Sticky honeydew on leaves. Black willow aphids (Pterocomma smithiae) or Little green and yellow willow aphids.
White powdery material on upper or lower surface of leaf. Powdery mildew.

Affecting Stems, Twigs and Small Branches:

Signs/Symptoms Cause
Large aphids on twigs. Black willow aphids (Pterocomma smithiae).
Scales. Oystershell scale (Lepidosaphes ulmi).
Cone-like gall at end of twig. Willow cone gall midges (Phabdophaga strobiloides).
Large beetles chewing bark. Cottonwood borer (Plectodera scalator).
Twigs with closely spaced pimple-like fruiting bodies (pycnidia). Dothiora canker.

Affecting Larger Branches or Trunks:

Signs/Symptoms Cause
Tunneling into wood. Poplar and willow borer (Argrilus difficilis), Flatheaded appletree borer(Chrysobothris femorata), Cottonwood borer (Plectodera scalator), or Bronze cane borer and related species (Aprilus aurichalceus).
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) in the bark. Cytospora canker (Valsa spp.,Leucostoma spp.).
Regular rows of holes in trunk. Sapsucker.
Open wounds, internal decay, swollen areas in stem. Stem decay fungi (Collybia velutipes,Phellinus igniarius and various fungal genera).
Fungal fruiting bories (mushrooms, conks) present. Stem decay fungi (Collybia velutipes,Phellinus igniarius and various fungal genera).
Clear to white oozing or frothy malodorous liquid exiting from wounds. Bacterial wetwood and slime flux.
Visiting oozing sap from trunk. Flies (fruit flies and other families).
Alternaria Leaf Blight
Alternaria Leaf Blight
Alternaria Leaf Blight
Alternaria Leaf Blight

Alternaria Leaf Blight

(Alternaria spp. (Alternaria solani on Tomato))

Alternaria is a fungus which causes leaf spotting. Leaf spots progress from older leaves to newer. Spots are circular with concentric rings, and often surrounded by a slight yellow area. Entire leaves may die and drop from the plant. Spots and cankers may also be found around stem ends on fruits and on stem.

Hosts

Cucurbits (cucumber, squash), Solanaceous crops (eggplant, pepper, potato, tomato) and other vegetables such as peas, onion and cabbage.

Lifecycle

Alternaria survives in plant debris and may be spread by insects or wind, and by rain/irrigation. Spores germinate in several hours during high humidity conditions. Infection occurs through natural plant openings if water remains on plant tissue for more than a couple of hours. After 2-3 days, first symptoms appear. Optimum temperatures for infection are 75-85° F, high humidity, and low fertility.

Controls

Type Instruction
Cultural This disease is spread by splashing water and by walking through plants when wet. Keep water off leaves. Water with soaker hoses or drip irrigation. Use 3 - 4 year rotations between susceptible crops. Maintain adequate nitrogen levels. Remove and destroy infected leaves.
Chemical Sulfur and copper can be sprayed when temperatures are between 55 and 85 F and weather is wet, to protect leaves from infection. These "least toxic" options are less effective when overhead irrigation is applied.
Biological Serenade WP sprayed at 5 to 7 day intervals.
Angular Leaf Spot
Angular Leaf Spot
Angular Leaf Spot
Angular Leaf Spot

Angular Leaf Spot

(Pseudomonas syringae pv. lachrymans)

This is a bacterial disease causing dark, angular spots between leaf veins; tear shaped droplets ooze from infected tissue. As the leaf dries and turns grey, leaf tissue tears and shrinks. Fruit may exhibit circular spots or rotted areas.

Hosts

Cucurbits (cucumber, squash), a similar strain infects beans.

Lifecycle

The bacteria over winters in plant debris and can persist for more than two years on dry leaves. It enters the plant through wounds or natural openings under wet conditions, then can be spread mechanically. Angular leaf spot is also seed borne (treat seed for 20 minutes with 120°F. water).

Controls

Type Instruction
Cultural Use 2 year rotations between cucurbit crops. Avoid wetting foliage with irrigation water. Use resistant cultivars when possible. Plant on raised beds. Excessive nitrogen fertilizer increases disease severity.
Chemical Copper can be sprayed to protect leaves when weather is wet and warm.
Anthracnose
Anthracnose
Anthracnose
Anthracnose

Anthracnose

(Multiple Species)

Symptoms vary with hosts. The most commonly seen symptom is a brown, irregular, blotchy area that expands between leaf veins. Black, sunken spots develop on fruits, leaves, and stems of vegetables. On woody plants there are two types of foliar symptoms. Most common is necrotic, irregular blotches that expand. Less common is round necrotic circles scattered throughout the leaf. Symptoms look much like leaf scorch or frost injury. On raspberry, circular, sunken spots on canes start out purplish and turn gray in the center.

Hosts

Woody Plants: Ash, maple, rose, sycamore, and many other deciduous trees and shrubs. Vegetables: Members of the Cucurbitaceae family (cucumber,squash), raspberry.

Lifecycle

Anthracnose fungi overwinter on blighted twigs or fallen leaf debris. Initial leaf infection occurs from late spring to mid-summer when moisture is frequent, humidity is high and temperatures are 70 - 80° F for vegetables and 45-55ºF for woody plants (the Anthracnose that infects woody plants is inhibited above 55ºF). Spores are disseminated by wind and splashing rain to buds, shoots, fruits and expanding leaves. Leaf symptoms become more noticeable in mid to late summer. The disease is most severe in wet springs and is checked by dry, hot weather.

Controls

Type Instruction
Cultural Keep irrigation off leaves.

Vegetables: Remove and destroy diseased twigs and leaves. Plant on raised beds and use plastic mulches to avoid splashing.

Raspberries: Remove and destroy old fruiting canes; use resistant cultivars such as Heritage, Meeker.

Woody Plants: Prune out dead wood and the water sprouts. Avoid drought stress by watering in dry spells and keeping the root zone mulched.
Chemical Vegetables: If weather is wet and temperatures >50°F, protect leaves with copper sprays as soon as leaves are fully expanded, copper and sulfur can injure sensitive plants like cucurbits, especially cucumber.
Raspberries: Avoid excessive Nitrogen fertilization. Bordeaux or Lime sulfur mix when first green tissue appears (timing is critical -too early is ineffective).
Woody Plants: Chemical control is usually not needed. Only needed if prolonged wet periods between 45-55ºF. Occurs during bud break and early shoot growth. Cooper is the least toxic option.
Aphids
Aphids
Aphids
Aphids

Aphids

(Multiple Species)

Very small (1/10 to 1/8 inch long), pear-shaped, soft-bodied insects ranging in color from light green through dark green, and pinkish to black. Aphids cluster on stems and/or undersides of leaves and produce "honeydew", a sugary protein mixture which is fed upon by ants and many of the aphids' natural enemies. Aphids move very slowly, if at all, and often appear to be attached to the plant surface by their sucking mouthparts. Young aphids, or nymphs, are wingless. Adults can be winged or wingless, depending on the species, environment, and time of season. There are many different kinds of aphids, most of which are specific to particular species, or genera, of plants. However, there are some aphids that attack many species of plants. Different species of aphids are often present at different times of the season.

Hosts

Lifecycle

Aphids overwinter as shiny, black eggs on twigs, budscales, and bark. Female aphids hatch from these overwintering eggs and give birth to live nymphs, all female, by parthenogenic reproduction (no fertilization by male aphids). Since mating is not required for reproduction, aphids can appear very quickly and build up large populations rapidly. A single female can produce 60-100 nymphs during its 20 to 30 day lifetime. Nymphs start to reproduce 6 to 10 days after birth. Winged male aphids are produced in the fall (mainly due to changing light conditions), and mating occurs. Fertilized females then lay overwintering eggs, generally on or near their preferred food source. When conditions become unfavorable (too hot, too dry, leaf tissue no longer succulent, decreased leaf nitrogen levels, over-crowding), winged adults are produced. These winged adults are capable of flying off to more favorable food sources. Fortunately, they are weak flyers!

Controls

Type Instruction
Cultural Aphid outbreaks are encouraged by cool, wet spring weather because their populations increase more rapidly than their natural enemies in this climate. Aphid outbreaks may also occur if controls used to treat other pests harm aphid predators (i.e., syrphid fly and lacewing larvae, ladybird beetles). Certain controls are more toxic to predators than others (see treatment options). Excessive fertilization, especially nitrogen, causes plants to maintain succulent growth, and may encourage aphids. Use less soluble nitrogen fertilizers (ammonium or urea-based forms or compost). Avoid pruning that encourages early spring growth. On aphid-susceptible species, prune in late spring after aphids arrive and prune a little at a time. Stop pruning before the end of July so you don't encourage a fall flush of growth.
Monitoring Check aphid populations regularly, especially in the spring when temperatures are between 60 - 80º F and new, succulent growth is present. Appropriate control methods vary by season. During aphids' dormant season, check for eggs (in late winter) to decide if a dormant control will be required. Check ten twigs per tree. If 30 to 50% have eggs, a dormant oil treatment may be helpful.

In early spring, check ten terminal shoots weekly; look especially at leaf undersides. If 25-50% of the terminals on young trees and shrubs are infested, some control may be required. Older, large trees can usually tolerate 50% or more terminal infestation before control is necessary. Check for predators. If predators are present at a ratio of 1:5, control is usually not required. If leaf curling is occurring already, treat immediately, especially on aphid-susceptible species like plum and green ash.
Biological Syrphid fly and lacewing larvae, gall midges (Aphidoletes), and ladybird beetles are effective aphid eaters. Evaluating several predators, researchers in Colorado found that lacewings were the best predators under hot conditions, and ladybeetles and Aphidoletes did best under cool temperatures. Overall, Aphidoletes was the best aphid predator of green peach aphid . Aphid populations are also decreased by fungus disease and parasites.

Diseased or parasitized aphids turn brown, puff up and stick to leaves.

Beauveria bassiana is a fungus (microbial insecticide) with some activity against aphids. Trade names -Naturalis, Botaniguard. It requires high humidity to be effective. Irrigate, then spray or use when weather is humid.
Mechanical Yellow sticky traps are useful to catch winged aphids, particularly in indoor growing situations, as long as populations are not too high. Sticky traps may catch some predator species as well as aphids.


In certain cases, using a silver or foil mulch under crop plants can confuse flying aphids that are searching for hosts. The silvery, reflective surface is thought to disrupt their sense of direction. When growing squashes or cucumbers, you may get somewhat the same effect by using silver-leafed varieties.

Washing with soapy water (with a dispenser attached to the hose) can knock some aphids off plants and reduce populations if done repeatedly. Washing may also enhance conditions for fungus diseases that attack aphids. Prune out infested terminals
Chemical Insecticidal Soap is only effective on soft-bodied insects. It has a short activity period. Repeat applications as needed. Avoid application in direct sun or at temperatures >85° F. Soap can burn foliage of tender plants. Wait 48 hours after application before releasing predators.

Two percent horticultural oil should not be applied in direct sun and/or at temperatures >85-90° F or <40° F. It may burn leaves, especially of sensitive or drought-stressed plants. Wait 48 hours after application before releasing predators.
Botanical Neem oil (Margosan-O, Bioneem, Greenlight, or Azatin) is best applied 2-3 times in succession, 7-10 days apart. Spray in the evening. It has a short activity period. Repeat applications!

Pyrethrum/Pyrethrin works best if combined with insecticidal soap: add 1/2 to 1 Tbsp. per gallon. Spray in the evening. This botanical has an extremely rapid breakdown rate, especially in sunlight. It also has a very short activity period. Repeat applications and spot spray if possible. It can harm predators and parasites.
Aphids 2
Aphids 2
Aphids 2
Aphids 2

Aphids 2

(Multiple Species)

Very small (1/10 to 1/8 inch long), pear-shaped, soft-bodied insects ranging in color from light green through dark green, and pinkish to black. Aphids cluster on stems and/or undersides of leaves and produce "honeydew", a sugary protein mixture which is fed upon by ants and many of the aphids' natural enemies. Aphids move very slowly, if at all, and often appear to be attached to the plant surface by their sucking mouthparts. Young aphids, or nymphs, are wingless. Adults can be winged or wingless, depending on the species, environment, and time of season. There are many different kinds of aphids, most of which are specific to particular species, or genera, of plants. However, there are some aphids that attack many species of plants. Different species of aphids are often present at different times of the season.

Hosts

Lifecycle

Life cycles: Aphids overwinter as shiny, black eggs on twigs, budscales, and bark. Female aphids hatch from these overwintering eggs and give birth to live nymphs, all female, by parthenogenic reproduction (no fertilization by male aphids). Since mating is not required for reproduction, aphids can appear very quickly and build up large populations rapidly. A single female can produce 60-100 nymphs during its 20 to 30 day lifetime. Nymphs start to reproduce 6 to 10 days after birth. Winged male aphids are produced in the fall (mainly due to changing light conditions), and mating occurs. Fertilized females then lay overwintering eggs, generally on or near their preferred food source. When conditions become unfavorable (too hot, too dry, leaf tissue no longer succulent, decreased leaf nitrogen levels, over-crowding), winged adults are produced. These winged adults are capable of flying off to more favorable food sources. Fortunately, they are weak flyers!

Controls

Type Instruction
Cultural Aphid outbreaks are encouraged by cool, wet spring weather because their populations increase more rapidly than their natural enemies in this climate. Aphid outbreaks may also occur if controls used to treat other pests harm aphid predators (i.e., syrphid fly and lacewing larvae, ladybird beetles). Certain controls are more toxic to predators than others (see treatment options). Excessive fertilization, especially nitrogen, causes plants to maintain succulent growth, and may encourage aphids. Use less soluble nitrogen fertilizers (ammonium or urea-based forms or compost). Avoid pruning that encourages early spring growth. On aphid-susceptible species, prune in late spring after aphids arrive and prune a little at a time. Stop pruning before the end of July so you don't encourage a fall flush of growth.
Monitoring Check aphid populations regularly, especially in the spring when temperatures are between 60 - 80º F and new, succulent growth is present. Appropriate control methods vary by season. During aphids' dormant season, check for eggs (in late winter) to decide if a dormant control will be required. Check ten twigs per tree. If 30 to 50% have eggs, a dormant oil treatment may be helpful.

In early spring, check ten terminal shoots weekly; look especially at leaf undersides. If 25-50% of the terminals on young trees and shrubs are infested, some control may be required. Older, large trees can usually tolerate 50% or more terminal infestation before control is necessary. Check for predators. If predators are present at a ratio of 1:5, control is usually not required. If leaf curling is occurring already, treat immediately, especially on aphid-susceptible species like plum and green ash.
Biological Syrphid fly and lacewing larvae, gall midges (Aphidoletes), and ladybird beetles are effective aphid eaters. Evaluating several predators, researchers in Colorado found that lacewings were the best predators under hot conditions, and ladybeetles and Aphidoletes did best under cool temperatures. Overall, Aphidoletes was the best aphid predator of green peach aphid . Aphid populations are also decreased by fungus disease and parasites.

Diseased or parasitized aphids turn brown, puff up and stick to leaves.

Beauveria bassiana is a fungus (microbial insecticide) with some activity against aphids. Trade names -Naturalis, Botaniguard. It requires high humidity to be effective. Irrigate, then spray or use when weather is humid.
Mechanical Yellow sticky traps are useful to catch winged aphids, particularly in indoor growing situations, as long as populations are not too high. Sticky traps may catch some predator species as well as aphids.


In certain cases, using a silver or foil mulch under crop plants can confuse flying aphids that are searching for hosts. The silvery, reflective surface is thought to disrupt their sense of direction. When growing squashes or cucumbers, you may get somewhat the same effect by using silver-leafed varieties.

Washing with soapy water (with a dispenser attached to the hose) can knock some aphids off plants and reduce populations if done repeatedly. Washing may also enhance conditions for fungus diseases that attack aphids. Prune out infested terminals
Chemical Insecticidal Soap is only effective on soft-bodied insects. It has a short activity period. Repeat applications as needed. Avoid application in direct sun or at temperatures >85° F. Soap can burn foliage of tender plants. Wait 48 hours after application before releasing predators.

Two percent horticultural oil (Sunspray or Volck Supreme Spray) should not be applied in direct sun and/or at temperatures >85-90° F or <40° F. It may burn leaves, especially of sensitive or drought-stressed plants. Wait 48 hours after application before releasing predators.
Botanical Neem oil (Margosan-O, Bioneem, Greenlight, or Azatin) is best applied 2-3 times in succession, 7-10 days apart. Spray in the evening. It has a short activity period. Repeat applications!

Pyrethrum/Pyrethrin works best if combined with insecticidal soap: add 1/2 to 1 Tbsp. per gallon. Spray in the evening. This botanical has an extremely rapid breakdown rate, especially in sunlight. It also has a very short activity period. Repeat applications and spot spray if possible. It can harm predators and parasites.
Apple and Thorn Skeletonizer
Apple and Thorn Skeletonizer
Apple and Thorn Skeletonizer

Apple and Thorn Skeletonizer

(Gymnosporangium juniperi-virginianae)

The adult moth is dark grey to reddish brown with a ½ inch wing span. The fully grown larvae is ½ inch long with a yellowish green body and a pale brown head.

Hosts

Apple, cherry, hawthorn, mountain ash, pear, and willow.

Lifecycle

Life Cycle: The adult moth overwinters and after mating in the spring lays tiny green eggs on the underside of the leaf near the midrib. The young larvae feed on the lower epidermis under a loose covering of silk. As they mature they move to the upper surface where they tie the edges of the leaf together at the base. The larvae then skeletonize the upper epidermis between the veins. This species develops rapidly later in the season in western Montana and produces 1 - 2 generations per year.

Controls

Type Instruction
Chemical Spinosad - Treat by spraying newly hatched larvae.

Azadirachtin (neem extract)
Apple Scab
Apple Scab
Apple Scab
Apple Scab

Apple Scab

(Venturia Inaequalis)

Spots begin as small olive green circles with velvety margins that enlarge and darken to brown/black. Spots on fruit are dark and may be cracked. Yellowing, browning, and death of leaves may result. Early drop may occur.

Hosts

Hosts: Apple and crabapple. Pear is host to another species of Venturia.

Lifecycle

Life Cycle: Scab fungi overwinter on fallen leaves. In the spring, overwintering spores become wet and are forcibly discharged and disseminated by the wind. Spores land on newly emerging leaf tissue and germinate in a film of moisture. After germination the relative humidity must be 95% or greater for infection to continue. Secondary infections occur throughout the summer if weather is wet and warm. Optimum temperatures for infection are 60 - 70°F. It takes 12 hours at a temperature of 53°F before infection occurs, while only 9 hours of leaf wetness are required for infection at 65°F.

Controls

Type Instruction
Cultural Keep water off of leaves and branches. Rake up and destroy infected leaves in the fall. Use resistant cultivars. Shred infected leaves to help speed up decomposition. Pruning to increase airflow.

See Disease Resistant Apple Cultivars
Biological In some studies, compost tea was effective as a preventative, while in other studies, compost tea had no effect.
Seranade MAX - label states it should be tank mixed with another fungicide.
Chemical Sulfur when the weather is wet and warm (see life cycle). Must be reapplied when precipitation (or irrigation) is >1 inch since the last application. Immunox or captan, if infection periods are high when leaves are first expanding - Check Pest Alert phone line: (406) 258-3820.
Armillaria Root Disease
Armillaria Root Disease
Armillaria Root Disease

Armillaria Root Disease

(Armillaria Spp.)

White mycelial (fungus) fans are present in the cambium and bark of roots and stems. Honey colored mushrooms (the fruiting bodies) may be found at the base of trees during wet periods in the fall. Some conifers (e.g. Douglas fir) produce resin at the tree base when attacked by Armillaria. Resin becomes evident when the fungus has moved up the roots to the root collar. Decayed wood initially is gray to brown-stained and appears water soaked. As the disease advances, the decay is white to yellow in color and is stringy or spongy.

Hosts

Grand and Douglas Fir under the age of 30 years primarily, but also occurring in many other conifers and hardwoods.

Lifecycle

The disease spreads from a host tree or stump to uninfected live trees in two ways: root systems of the two trees come in contact and knit together, or fungal mycelium grow through the soil from infected to susceptible tree roots. The fungus spreads along the root system of the tree penetrating its bark and entering the cambium. It then continues to spread along the root until it reaches the root collar where it spreads to other primary roots. Death occurs when the tree is girdled at the root collar, when bark beetles attack, or windthrow occurs. Armillaria survives as a saprophyte on dead roots and stumps for 20-30 years. Contact with old roots can infect new trees.

Controls

Type Instruction
Removal Remove diseased tree stumps, roots and all. Plant resistant species such as Western Larch.
Army Cutworm
Army Cutworm
Army Cutworm

Army Cutworm

(Euxoa Auxiliaris)

Adults are 1½ inch moths with dark gray wings. Larvae are tan, green, or black, 1½ inches long, and have an inverted Y on their heads.

Hosts

Corn, celery, beets, peppers, lettuce, and other vegetables.

Lifecycle

The caterpillars overwinter and emerge in early spring, when they do their heaviest damage. After several weeks, they enter the soil, pupate, and emerge as 'miller-type' moths. There is one generation per year.

Controls

Type Instruction
Biological Scout your plants every 2 to 3 days; apply BtK in granular or ES (emulsifiable suspension) form if 20% of leaves have "shot holes" in them, being particularly attentive to the undersides of the leaves. (BtK is most effective on small larvae, 1/4 to 3/4 inch long, in their first instar.) See Bacillus Thuringiensis.

FOR CORN: Spray directly to leaf whorls, and to silks after they have wilted. Apply Dipel (Bt) at 1 lb/A or Xentari at 1.5 lb/A. For late plantings, apply Xentari once at tassel; hand apply a corn oil/Bt mix directly to corn silks. Apply any of the various horticultural oils to ear tips 4 - 5 days after the silks wilt to discourage worms already present.
Traps Blacklight traps catch male and female moths; pheromone traps catch only the males. Both traps are most effective as indicators of population levels.
Chemical Spray Spinosad in the evening
Mechanical Use floating row covers, being sure to remove them when plants bloom so that pollination is not hindered. (Remay has been shown to be the most effective type of floating row cover for these types of pests.)
Ash Plant Bug
Ash Plant Bug
Ash Plant Bug

Ash Plant Bug

(Tropidosteptes Amoenus)

Light brown true bug about ¼ to ½ inch long . Nymphs are oval, shiny yellowish or reddish brown and lack wings.

Hosts

Ash.

Lifecycle

Life Cycle: Overwintering eggs are laid under loose bark. Nymphs hatch out in late spring and feed on lower leaf surfaces. Most injury occurs in the spring since the nymphs begin to mature by early summer. First generation adults insert eggs into the midribs of leaves and a second cycle of feeding occurs in late summer. Second generation adults produce overwintering eggs.

Controls

Type Instruction
Chemical Use insecticidal soap if >40% of leaves are infested. Injury is mostly cosmetic only.
Ash Yellows
Ash Yellows
Ash Yellows

Ash Yellows

(Phytoplasma)

Infected ash trees show a variety of symptoms. The most dramatic field symptom is the presence of witches' brooms on the trunk and major limbs. Leaves on the broom tend to be small and chlorotic; the branches do not have a dominant shoot but are made up of many shoots. After several years of minimal growth, leaves will only appear in tufts at the end of branches.

Hosts

Ash.

Lifecycle

The disease is caused by a phytoplasma, a prokaryotic organism similar to a bacteria, but simpler in structure. Phytoplasmas live in the phloem tissues of trees and infect trees systemically. Insects such as leafhoppers, spittlebugs, and psyllids are the major carriers of infection.

Controls

Type Instruction
Removal Remove infected trees if badly infected.
Asparagus Beetles
Asparagus Beetles
Asparagus Beetles

Asparagus Beetles

(Crioceris Asparagi)

Adults are blue-black, ¼" long, with yellow-orange spots and red margins. Larvae are 1/3" long, humpbacked grubs that are green to dark gray with black heads.

Hosts

Asparagus and related crops.

Lifecycle

There are 2-3 generations per year. Adults overwinter; they emerge and mate in spring. In one week, eggs hatch and the larvae feed. Later, they drop from the plant and pupate in the soil.

Controls

Type Instruction
Cultural Mow down the foliage in late winter or early spring to get rid of overwintering areas. Pick asparagus regularly.
Mechanical The larvae feed on asparagus berries; shake off the berries onto a sheet and destroy them.
Botanical Pyrethrum can be sprayed on larva.
Chemical Spinosad sprayed on larva.
Aster Yellows
Aster Yellows
Aster Yellows
Aster Yellows

Aster Yellows

(Phytoplasma)

This disease causes twisted distorted new growth (including leaf-like petals) and a yellowing/reddening of leaf tissue; it also causes hairy roots in carrots.

Hosts

Vegetables: Carrots, celery, lettuce, parsnips . Flowers: Asters, Echinacea, and annual flowers such as zinnia.

Lifecycle

Aster yellows is caused by Phytoplasma spread only by leafhoppers. These pests overwinter in warmer regions then migrate north. After feeding upon infected plants, they can then transmit the disease through feeding. Peak infection periods are in late summer/early fall.

Controls

Type Instruction
Cultural Aster yellows is caused by Phytoplasma spread only by leafhoppers. These pests overwinter in warmer regions then migrate north. After feeding upon infected plants, they can then transmit the disease through feeding. Peak infection periods are in late summer/early fall.
Bacterial Brown Spot
Bacterial Brown Spot
Bacterial Brown Spot
Bacterial Brown Spot

Bacterial Brown Spot

(Pseudomonas Syringae PV. Syringae)

Symptoms vary with the host plant. Leaf symptoms are small brown/black, angular-shaped spots with yellow halos. Spots coalesce and entire leaves may die. Infected flower clusters fail to open, turn brown and excude amber-colored gum. Infected twigs turn black. Infection is usually limited to new growth; stems one year or older seldom have lesions. Amber-colored gum occurs on bark surface around sunken cankers. Underneath cankers the inner bark is reddish brown and streaked.

Hosts

Lilac, cotoneaster, ornamental and fruiting cherries, plums, and privet. Vegetable crops(e.g.-broccoli, pea) are susceptible to various subspecies of P. syringae.

Lifecycle

Bacteria are spread from plant to plant by splashing water. Infection takes place through natural openings and wounds. Canker development is optimum at temperatures of 72-79° F. In slightly below freezing temperatures, the bacterium forms an ice nucleus which disrupts plant tissue and causes symptoms typical of frost or freeze damage. The bacterium overwinters on plant surfaces.

Controls

Type Instruction
Cultural Cold-stressed and wounded plants are more susceptible. Avoid late-season fertilization with nitrogen, and early-season or fall pruning of susceptible species, especially white-flowered lilacs (prune after bloom!). Prune out infected branches or infected leaves (vegetable crop) on a hot, dry day. Sterilize pruning tools between cuts. Protect with an antitranspirant spray (10 Tbsp./gallon of water). When weather is warm (>70° F.), keep irrigation water off leaves and lower branches and trunk. Plant resistant cultivars and or rootstocks. Delay dormant pruning until Febuary-March.
Chemical Spray Bordeaux Mix on woody perennials as buds begin to break in the spring. Protect with copper sprays if rain and warm (65 - 75° F.) weather occur. For vegetable crops, treat seed with hot water or bleach and use 2 year rotations. On vegetable crops, protect from rain and frost with floating row covers.
Bacterial Spot
Bacterial Spot
Bacterial Spot
Bacterial Spot

Bacterial Spot

(Xanthomonas Campestris)

Leaves, stems, and fruit develop water-soaked spots that turn brown, circular spots without concentric zones as for Early Blight. Spots on leaves are frequently surrounded by a yellow halo. The center may fall out. Fruit spots are at first water-soaked and later become raised and scabby.

Hosts

Tomatoes and peppers.

Lifecycle

The bacterium overwinters on plant debris and seed. It is favored by wet conditions and temperatures of 75 - 86° F.

Controls

Type Instruction
Controls:
Keep water off of leaves. Use a 3 year rotation. Treat seed with hot (122° F.) water for 25 minutes or 20% bleach solution for 20-40 minutes. Carry out proper sanitation in the greenhouse or field to minimize infection. Spray copper during wet, warm (>75° F.) weather. Applications of Sonata or Seranade (Bacillus subtilis QST 713) on 7-14 day intervals.
Bacterial Wetwood
Bacterial Wetwood
Bacterial Wetwood

Bacterial Wetwood

(Slime Flux)

Wetwood is most easily recognized by the presence of a liquid that oozes from wounds, crotches, branch stubs, frost cracks, or other weak points of the wood or bark. As the liquid flows down the bark, vertical dark or light streaks remain. Oozing sap is initially colorless. After colonization by various bacteria and yeast, the liquid becomes slimy and is often called slime flux. Symptoms of nutrient deficiency may appear due to poor water movement within the affected tree.

Hosts

Most commonly: aspen, poplar, willow, and elm; also affects fruit trees, ash, birch, fir, maple, mountain ash, and pines.

Lifecycle

Very little is known about the bacteria and other microorganisms that cause wetwood. Bacteria are assumed to enter healthy trees through the root system, rather than being carried by insects. Drought stress appears to favor the development of the disease.

Controls

Type Instruction
No know controls are known to avoid initiation or development. Keep trees well-watered. Recently transplanted trees may ooze slime if roots are not established and cannot supply adequate water. Fertilizing wetwood-infected trees is recommended if the tree shows nutrient dificiencies.
Bacterial Wilt
Bacterial Wilt
Bacterial Wilt

Bacterial Wilt

(Erwinia Tracheiphila)

This bacteria causes wilting and death. White ooze is visible at any cut in the plant tissue. If you touch the cut and then draw your finger slowly away, the ooze will form strands.

Hosts

Cucurbits (cucumber, squash).

Lifecycle

The disease is spread by cucumber beetles and overwinters in their guts. When the beetles feed, the bacteria enters the plant's water-conducting tissues and begins to multiply.

Controls

Type Instruction
Cultural / Mechanical The only measures you may employ are preventative. Keep your plants in general good health. Control populations of cucumber beetles which help spread the disease. Use row covers over seedlings and transplants to prevent cucumber beetles access.

Remember to remove row covers when vines start to run and are mature enough for pollination.
There is no known remedy once plants are infected. To test for infection, cut out disease area, press drops of sap onto your hand; if sap is milky, sticky and stings, the plant is infected. Destroy immediately!
Beet Armyworm
Beet Armyworm
Beet Armyworm

Beet Armyworm

(Spodoptera Exigua)

Caterpillars are smooth and light olive green. Dark lateral stripes and fine wavy light stripes along the back are the primary markings. Adults have slightly mottled grayish brown forewings with a plae spot in the middle of the front margin.

Hosts

Awide range of vegetables including lettuce, cabbage, cauliflower, broccoli, brussell sprouts, beets, tomato, bean, onion, and asparagus.

Lifecycle

Winter is usally spent as a pupa in a shallow earthen cell. Adults emerge in the spring, and females lay eggs in masses, which is covered with hairs, giving it a cottony appearance. Early-stage larva feed as a group and skeletonize the leaves. Older larva disperse and feed singly, often tunneling into plant parts. The life cycle can be completed in about a month under normal conditions, several generations are common per season.

Controls

Type Instruction
Biological Several native parasitic insects have provided adequate control, including a species of tachinid fly and species of braconid, ichneumonid, and chalid wasps. Spiders, pathogens, and other predators have also contributed to control.
Chemical Spinosad - Treat by spraying newly hatched larvae.
Botanical Bacillus thuringiensis (Bt-K). Treat newly hatched larvae. This works best when temperatures are warm (>50ºF).
Black Knot
Black Knot
Black Knot

Black Knot

(Dibotryon Morbosum formerly Apiosporina Morbosa)

The fungus forms long, irregularly-shaped, black galls along branches and twigs and rough, black, sunken cankers on stems. Tips of infected branches often die back. Severe infections can kill whole limbs, and the tree may be stunted.

Hosts

Chokecherry, plums, cherries, and other trees and shrubs in the genus Prunus.

Lifecycle

Wind and rain-disseminated spores infect new growth in the spring when >6 hours of rain occurs at temperatures between 55-77° F. The spores enter through green shoots of the host plant. Galls are seen mid to late summer when the fungal hormones cause swelling. The following spring after infection, the fungus produces fruiting bodies. Once established, cankers and galls are perennial and will spread along the limbs. The fungus may spread systemically through the xylem and phloem to produce cankers on other limbs and the trunk.

Controls

Type Instruction
Cultural Prune out black galls in late summer and fall on a hot, dry day. Keep water off leaves, branches, and trunks.
Chemical When weather is wet and warm (> 60° F.), protect new growth with captan or sulfur. Only effective if galls have been pruned out.
Black Rot
Black Rot
Black Rot
Black Rot

Black Rot

(Xanthomonas Campestris)

Black rot is caused by a bacterium. It turns young plants leaves yellow, then brown; eventually they die. Older plants begin to turn yellow from leaf edges inwards in a V-shaped pattern; veins turn black. Black rings and yellow ooze are present in cut stems.

Hosts

Broccoli, cabbage, cauliflower, brussels sprouts, kale, kohlrabi and other plants in the cabbage family, radish.

Lifecycle

The bacterium overwinters on seeds and in plant debris. It can remain infectious for up to 2 years. Infection occurs through wounds or natural openings, especially during warm (80-86°F), humid weather. Transmission occurs via insects, water, and/or mechanical means (such as on tools).

Controls

Type Instruction
Cultural Use 2-3 year rotations and destroy infected plants. Grow resistant varieties.
Chemical Spray copper if weather is wet.
Mechanical Treat seed with hot (120° F.) water 30 minutes before planting.
Black Spot
Black Spot
Black Spot

Black Spot

(Diplocarpon Rosae)

Round, black spots with slightly fringed margins on upper leaf surface. Yellow halos around the black spots can spread into yellow blothcs and leaves may fall prematurely. Raised, purplish spots may also be present on canes.

Hosts

Rose.

Lifecycle

When weather is wet and humid and temperatures are 65-70 F, black spot is most infectious. It over winters on fallen leaves or infected canes. Black spot infects newly expanding leaves in the spring if leaves are continuously wet for 9 hours or more. Stem infections cause purplish or black blisters on young canes.

Controls

Type Instruction
Cultural Keep water off of leaves and canes, or irrigate after 10 am and before 3 pm to maximize drying conditions. Prune to maintain good air movement. Plant resistant cultivars. Rake up and burn all leaves at the end of the season. Prune canes back to two buds if canes are infected. See Disease Resistant Rose Varieties
Chemical Start at bud break with a lime-sulfur delayed dormant spray. Protect new leaves with sulfur if weather is wet and warm. Sprays every one to two weeks if you have had past infections. Captan, potassium bicarbonate or fixed copper sprays may be used in rotation.
Black Vine Weevil
Black Vine Weevil
Black Vine Weevil
Black Vine Weevil

Black Vine Weevil

(Otiorhynchus Sulcatus)

Adults are dark-gray or black snout beetles about 1/3 inch long with wing covers marked with gold flecking; larvae are weevils, greater than 1/4 inch long, dark in color and thick bodied.

Hosts

Strawberries, clematis, euonymus, lilac, rhododendron.

Lifecycle

Root weevils overwinter in the larval stage around the roots of the host plant. Adults emerge during late spring and early summer and feed for about two weeks before laying eggs. They feed at night and move to debris around the base of the plants during the day. Eggs are laid throughout the summer in soil cracks around the host plant. Larvae feed on roots during the summer and fall; peak feeding occurs the following spring. Larvae pupate in the soil surrounding the host plant. There is one generation per year. Adults often envade houses in early summer.

Controls

Type Instruction
Biological Parasitic nematodes (Steinernema carpocapsae) applied to black plastic mulched strawberries in the drip irrigation system twice, once in the spring and again in late summer, reduced black vine weevil by 50%.

Parasitic nematodes (Heterorhabditis bacteriophora) applied at 5,000/pot effectively controlled black vine weevil in Maryland. H. bacteriophora efficacy is reduced at soil temperatures below 68° F. Late summer application is recommended in western Montana. Keep soil moist after application. These nematodes do better in pots if sub-irrigated rather than overhead-irrigated.
Chemical Beauveria bassiana is a fungus which causes a disease known as the white muscadine disease in insects. When spores of this fungus come in contact with the cuticle (skin) of susceptible insects, they germinate and grow directly through the cuticle to the inner body of their host. Here the fungus proliferates throughout the insect's body, producing toxins and draining the insect of nutrients, eventually killing it. Therefore, unlike bacterial and viral pathogens of insects, Beauveria and other fungal pathogens infect the insect with contact and do not need to be consumed by their host to cause infection. Trade names Botanigard or Naturalis.
Black Witches Broom
Black Witches Broom
Black Witches Broom

Black Witches Broom

(Apiosporina Collinsii)

Apiosporina collinsii produces perennial mycelium in branches and fruiting bodies on leaf surfaces. Mycelium grows mainly toward the tip of the twig and enters buds, petioles, leaf blades, and flowers. As additional shoots develop in the leaves, the fungus grows into new tissue and causes development of abnormally short, thick and numerous twigs. On shaded branches, infection is swollen and bent toward the ground. Diseased branches in open areas develop loose brooms. Many twigs in brooms die back during winter. Leaves on a broom are dwarfed and yellow. Branches that have brooms become less vigorous but will not die from the parasite. The disease has little net effect on the plant unless brooms are numerous.

Hosts

Various species of serviceberry (Amelanchier).

Lifecycle

Life Cycle: This disease is most common in woodland or stream bottom habitat. Spores are released in the spring, they germinate in bark fissures or axils of leaves or buds, and the fungus then invades the twigs. Where summers are dry here in the Northwest, the first crop of leaves may be cast and replaced at midsummer by a secound crop more sickly than the first.

Controls

Type Instruction
Prune out infected branches and keep irrigation off of plants.
Blackleg
Blackleg
Blackleg
Blackleg

Blackleg

(Erwinia Caratova)

Inky, black decay which starts at the tuber and progresses up into stems. Plants yellow and wilt. Leaves roll upwards at the margins.

Hosts

Potatoes (subspecies of this bacterium affect other crops including sugar beets and sunflowers).

Lifecycle

Seed tubers transmit the disease, but the bacteria may also overwinter in infected crop debris. The disease is favored by moist soil and cool temperatures (60 - 65° F.).

Controls

Type Instruction
Plant in well-drained raised beds. Avoid excess irrigation. Plant when soil temperatures are above 50°. Plant only certified, disease-free seed tubers, if posible use whole smaller seed potatoes that do not have to be cut. Remove and destroy infected plants.
Boxelder Bugs
Boxelder Bugs
Boxelder Bugs

Boxelder Bugs

(Leptocoris Trivittata)

Boxelder bugs are brownish-black and about 1/2 inch long. They have three red lines on the head and a bright red abdomen beneath the wings.

Hosts

Boxelder, ash, and maple.

Lifecycle

Life Cycle: Adults overwinter in protected sites (including homes). They emerge in mid-spring and lay eggs. The first generation nymphs feed on the boxelder, ash, and silver maple seeds, fruit trees and various low growing plants until they become adults in mid-summer. Females then lay eggs on the seeds of boxelder trees. The nymphs mature on these seeds into late fall. After the first frosts boxelder bugs move to winter shelter; during this time they invade buildings.

Controls

Type Instruction
Controls:
No control required. Nusiance pest only - will not harm plants or buildings. Vacuum up the bugs and seal the cracks in foundations and windows to keep the bugs from entering the buildings.
Bronze Birch Borer
Bronze Birch Borer
Bronze Birch Borer
Bronze Birch Borer

Bronze Birch Borer

(Agrilus Anxius)

Adults are olive-brown beetles with blunt heads and tapering bodies about ½ inch long. Larvae are white wormlike grubs with an enlarged flattened area just behind the head and no legs.

Hosts

Birch.

Lifecycle

Adults emerge in late May through June. Females lay eggs primarily on unshaded sides of trunks and branches. Larvae hatch June through July and tunnel into birch tree cambium. There is one generation per year. Larvae overwinter and pupate into adult beetles in early spring.

Controls

Type Instruction
Cultural Keep birch well watered during the dry months of July and August. Mulch with 1 - 3" of composted wood bark. Remove and discard limbs with raised ridges on the bark and/or top dieback in late winter. DO NOT PRUNE after the first of May - fresh wounds attract adults. Betula nigra (River Birch) Heritage is somewhat resistant.
Chemical Preventative insecticide applications of carbaryl to the trunk and lower limbs in early summer when adults are active. Check Pest Alert Hotline (258-3820) for timing.

Soil injections of imidacloprid in late fall.
Bronze Birch Borer
Bronze Birch Borer
Bronze Birch Borer
Bronze Birch Borer

Bronze Birch Borer

(Agrilus Anxius)

Adults are olive-brown beetles with blunt heads and tapering bodies about ½ inch long. Larvae are white wormlike grubs with an enlarged flattened area just behind the head and no legs.

Hosts

Birch.

Lifecycle

Adults emerge in late May through June. Females lay eggs primarily on unshaded sides of trunks and branches. Larvae hatch June through July and tunnel into birch tree cambium. There is one generation per year. Larvae overwinter and pupate into adult beetles in early spring.

Controls

Type Instruction
Cultural Keep birch well watered during the dry months of July and August. Mulch with 1 - 3" of composted wood bark. Remove and discard limbs with raised ridges on the bark and/or top dieback in late winter. DO NOT PRUNE after the first of May - fresh wounds attract adults. Betula nigra (River Birch) Heritage is somewhat resistant.
Chemical Preventative insecticide applications of carbaryl to the trunk and lower limbs in early summer when adults are active. Check Pest Alert Hotline (258-3820) for timing.

Soil injections of imidacloprid in late fall.
Brown Felt Blight
Brown Felt Blight
Brown Felt Blight

Brown Felt Blight

(Herpotrichia Juniperi: Firs and Spruces, Neopeckia Coulteri: Pines)

Brown, felt-like mats grow over needles and twigs binding them together and killing them. Most evident in spring after snow melts.

Hosts

Pine or other conifers (usually only at high elevations). See fir, spruce.

Lifecycle

Under cover of snow, the fungus envelops the branch (fungus grows at 26 - 32°F) in a gray mycelium. After snowmelt and exposure the fungus stops growing and turns a dark brown. The secound winter, fruiting bodies develop under the snow.

Controls

Type Instruction
REMOVE AND DESTROY infected branches.
Brownheaded Ash Sawfly
Brownheaded Ash Sawfly
Brownheaded Ash Sawfly

Brownheaded Ash Sawfly

(Tomostethus Multicintus)

The larvae are pale green and worm-like with dark heads. Adults are small, black wasps.

Hosts

Ash.

Lifecycle

The brownheaded ash sawfly overwinters as a full grown larva within a cocoon around the base of previously infested ash trees. Pupation occurs in early spring and adult wasps swarm ash trees. Females lay eggs on new leaves, resulting in a slight distortion of these leaves. Emerging larvae feed on leaves, producing small pinhole feeding wounds. Mature larvae can defoliate leaves leaving only the main veins. Larvae mature by early summer, when they shed a papery larval skin that remains attached to the leaf. They then crawl to the ground around the host tree where they form a protective cocoon. There is only one generation per year.

Controls

Type Instruction
Chemical Spray with insecticidal soap, spinosad, or neem extract if >40% of leaves are infested with larvae.
Cabbage Loopers
Cabbage Loopers
Cabbage Loopers
Cabbage Loopers

Cabbage Loopers

(richoplusia Ni)

Larvae are light green, 1/2 inch long, with a white stripe along each side of the body. They hump their middle sections when they move.

Hosts

Cabbage family plants (cabbage, cauliflower, brussels sprouts, broccoli, kohlrabi, kale), beans(pods), celery, lettuce, radish, tomatoes.

Lifecycle

Larvae feed at the base of developing cabbage heads inside the leaves, excreting a greenish, jellylike substance as they go.

Controls

Type Instruction
Pheromones Traps are available to catch male cabbage looper moths.
Biological Spray Bt if you find 1 worm per 2 plants. Bacillus thuringiensis (Bt) must be ingested by worms before it has any effect. Good coverage of upper and lower leaf surfaces is important. Use lots of water and insecticidal soap as a sticker (1-1/2 oz/gal) when spraying Bt. Using a feeding attractant, such as molasses (½ - 1 oz/gal), may improve control. Bt breaks down rapidly in sunlight (usually within 24 hours). It is best to apply it in the evening. Bt is washed off leaves by rainfall of 1/2 to 1 inch and thus must be reapplied if rain occurs within a few hours of application. Bt is most effective if sprayed when temperatures are above 45° F. Use Bt within 2 years of purchase - it does not store well.

Flies and wasps parasitize these worms. Eggs and larvae are both fed upon by other beneficial insects and birds.
Carrot Rust Fly
Carrot Rust Fly
Carrot Rust Fly

Carrot Rust Fly

(Psila Rosae)

Adults are housefly look-alikes with yellow heads. Larvae are yellow-white maggots.

Hosts

Carrots, Celery.

Lifecycle

Pupae overwinter in the soil. Flies emerge in spring. Eggs are laid in moist soil near host plants; larvae feed on roots and on plant tissue near soil line. The cycle occurs over 2-3 months, and 2 generations may occur in a season depending on weather.

Controls

Type Instruction
Biological Apply parasitic nematodes to soil in late spring. Keep soil moist after application.
Cultural Plant late to avoid larva cycle (after June 1). Avoid following sod with your carrot crop. Cover crop with row covers as soon as seedlings emerge. Don't harvest late in the year and don't overwinter carrots in the soil.
Carrot Weevil
Carrot Weevil
Carrot Weevil
Carrot Weevil

Carrot Weevil

(Listronotus Oregonensis)

Adults are dark-brown snout beetles, 1/4 inch long. Larvae are creamy white grubs with reddish-brown heads.

Hosts

Carrots, celery, parsnip.

Lifecycle

Adults emerge early in the spring to lay eggs in stalks near the soil line. The young grubs tunnel into the stalks and work their way downward into the roots. They become full grown in 3 to 4 weeks and pupate nearby in the soil. Most damage has occured in soils with high organic matter.

Controls

Type Instruction
Cultural Use a 3-year rotation. Cover new seed beds with floating row cover.
Biological Parasitic nematodes can be somewhat effective against larvae. Apply when planting and water in.
Botanical Check plants regularly; if more than one adult is seen per 10 foot row, spray pyrethrum.
Cedar Apple Rust
Cedar Apple Rust
Cedar Apple Rust

Cedar Apple Rust

(Gymnosporangium Juniperi-Virginianae)

Orange leaf spots, defoliation and fruit and twig deformities. Juniper infections appear as swellings on deciduous host or galls on twigs, these form gelatinous orange fruiting bodies in the spring.

Hosts

Rust occurs anywhere that perennial hosts (juniper, cedar, etc.) grow near their deciduous hosts(apple, hawthorn).

Lifecycle

The rust fungi (following infection) overwinters on juniper and cedar. Galls start to form during the spring and for the next 20 months. Rainsplash or wind to nearby hawthorn disperses the spores. Under conditions of high humidity, dispersal may be for several miles. Infection of the broadleaf hosts results in formation of orange-yellow spots and later developement of hair like structures(aecia) on the leaf underside. Spores are dispersed by wind and infect the juniper during late summer or early fall.

Controls

Type Instruction
Cultural Optimal temperatures for rust infections are 64-70° F. High temperatures (>85° F.) and dry weather discourage rust disease.


Irrigate early enough in the day so that plant surfaces have time to dry before the cooler temperatures of evening. Keep irrigation off of leaves, branches, and trunk.

Prune plants for good air circulation.

Plant resistant varieties.
Mineral Sulfur or copper soap sprays can be effective if sprayed preventatively in the spring when rust infection periods occur(wet with temperatures 60-70ºF).
Cercospora Leaf Spot or Blight
Cercospora Leaf Spot or Blight
Cercospora Leaf Spot or Blight

Cercospora Leaf Spot or Blight

(Cercospora SPP.)

Spots with tan-pale, round centers and dark margins are visible. Symptoms appear on older leaves first and can cause defoliation.

Hosts

Beets, carrots, celery, cucurbits (cucumber, squash), eggplant, tomatoes (different species on each vegetable). Also found on perennial flowers, Roses, Dogwood, and Viburnum leaves.

Lifecycle

The fungus overwinters on plant residue. Spores are carried on the wind relatively long distances. Infection requires free water on leaf surfaces and temperatures of 79-90° F.

Controls

Type Instruction
Cultural Grow resistant varieties. Soak seed in 122° F. water for 25 minutes before sowing. Use a three-year rotation between each susceptible vegetable crop (ie: tomatoes, carrots, lettuce). Keep water off leaves. Increase air movement by staking if possible.

To encourage new leaf growth, use foliar fish fertilizer each time you irrigate.
Chemical Spray sulfur, copper or neem at first sign of the disease. (Cucurbits are very copper sensitive; test your varieties before spraying; use copper sprays very sparingly, and never on bright, sunny days with temperatures above 80 to 85° F).
Cicadas
Cicadas
Cicadas

Cicadas

(Dog Day (Tibicen Dorsata), Putnam's (Platypedia Putnam))

Large, dark-colored insects ranging from 11/2-2 inches in length, with bulging eyes and membranous wings folded tentlike over the body. Nymphs are brown and have stout bodies.

Hosts

Dog-day cicada: Boxelder and cottonwood; Putnam's cicada: Crabapple, maple, mountain ash, oak, pear.

Lifecycle

The entire immature stage occurs underground. When full grown, nymphs emerge from the soil, crawl onto the lower portion of trees and cast off their nymphal skins. From late spring through mid-summer, adults are present. Males produce a clicking/buzzing sound to attract females. After mating, females lay eggs into the twigs of various host trees. After hatching, nymphs drop to the ground and burrow into the soil where they spend the next 2-5 years feeding on the roots of the host plant.

Controls

Type Instruction
None necessary.
Codling Moth
Codling Moth
Codling Moth

Codling Moth

(Cydia Pomonella)

Adults are 1/2 to 3/4 inch gray moths with a dark band. Larvae are cream colored, 1/4 to 1/2 inch long caterpillars with dark heads.

Hosts

Apples, pears, and (on RARE occasions) plums.

Lifecycle

Codling moths over winter as larvae underneath apple tree bark or occasionally in the soil at the base of host trees. Adults emerge in the spring when temperatures reach 50° F. Optimum temperature for codling moth development is 68-81° F. Cool temperatures (<55° F) and rainy weather limit codling moth flight and thus mating. High temperatures (>92° F) also limit codling moth flight. After mating, codling moth adults lay eggs singly on or near the fruit. Each moth lays between 30-130 eggs. Eggs hatch and tiny white (1/8" long) codling moth larva feed on apple fruit surface producing shallow, brown, sawdusty spots. Within 4 to 48 hours larva begin to tunnel into the fruit within days. Larva develop inside fruit, then leave the fruit and crawl down the tree trunk to pupate on tree bark or in the soil. There are 2-3 generations of codling moths in Missoula per year.

Controls

Type Instruction
Cultural Remove and use or destroy apples that drop to the ground or are left on the tree.

Adult moth mating is disrupted by, and larval mortality is increased by, rainfall especially in the evening (when moths mate). In one experiment, four hours of overhead irrigation daily in the evening during moth flight and larval hatch decreased fruit injury by 90%. Use pheremone traps to measure peak moth flight.

Tree bands placed around the base of apple trees and covered with a sticky substance like Tanglefoot have been reported to trap as high as 65% of over wintering codling moths. However, fruit damage was still as high as 43-57% if tree banding was the only codling moth control.
Biological Predation removes 10-20% of codling moth eggs laid in unsprayed orchards. Major predators of codling moth eggs are minute pirate bugs, earwigs, lacewings, predatory thrips, spiders, birds, ground beetles, and native parasitic wasps.

Trichogramma wasp releases have been used as one tool in an integrated codling moth control program in Washington state.

Codling moth granulosis virus sprayed repeatedly to coincide with egg hatch reduced codling moth injury 60-80% in California tests. In Colorado Organic orchards, granulosis virus (Cydx and Virosoft) is sprayed at 1st hatch (250-300 degree day hours after 1st male moth catch) and then bi-monthly through second generation larval hatch. Colorado orchardists use Spinosad (Entrust) alternating with granulosis bi-monthly.

Bacillus thuringiensis may have limited efficacy against codling moth larvae if it is sprayed repeatedly every 3-5 days to coincide with first and second generation larval hatch. It is best used in combination with other management tools.
Mating Distruption For larger apple blocks(5 acres or more) or neighborhoods, special codling moth pheromone dispensers can be purchased and applied at 400/acre to confuse and prevent male moths from finding and mating with female moths. Mating disruption is not a management tool for less than 5 acres of fruit production.

Mating disruption has resulted in successful codling moth control in commercial apple and pear orchards in CA, OR, WA, and VA when codling moth density was low to moderate.
Traps Sweet food baits attract Lepidopteran adults and larvae. Codling moths are attracted to molasses and palm sugar bait traps with a 10% solution placed in yellow-jacket domes and put in the lower canopy of trees. More FEMALE codling moths than male codling moths are attracted to molassas traps.

Codling moth pheromone traps are available in Missoula at nurseries and garden supply stores. They catch only MALE moths and will not control FEMALE moths in most situations. Pheromone traps are important, however, in order to know when the first codling moth adults appear and thus predict the first larval hatch. Missoula County Extension monitors codling moth development and reports larval hatches on a Pest Alert Phone Line, (406) 258-3820.

Blacklight traps which run from sundown until 11 pm reduced CM populations by 39% without catching large numbers of non-target night-flying moths.
Chemical NonOrganic options include carbaryl, malathion, permethrin, and acetamiprid. Add 1 Tbsp insecticidal soap and molasses to each gallon of spray. Spray in the evening.
Spinosad (Entrust, Conserve, Monterey Garden & Insect Spray etc...) sprayed bimontly when codling moth larvae first hatch has been most effective in combination with bimontly alternating sprays of granulosis virus (Cydx , Madex and Virosoft). Spinosad reportedly increases codling moth sensitivity to other insecticides. Neem (GWN 1535) and pyrethrins can be sprayed to target first and second generation larval hatch. Kaolin clay (Surround 95 WP) can be sprayed weekly or bi-monthly when apple blossom petals fall and fruit begins to form. Surround should be used in conjunction with first and second generation larval sprays since codling moth control is inadequate if used alone. To all chemical sprays add 1 Tbsp/gal. molasses and 1 Tbsp/gal insecticidal soap for increased efficacy, spray in the evening.
Colorado Potato Beetles
Colorado Potato Beetles
Colorado Potato Beetles
Colorado Potato Beetles

Colorado Potato Beetles

(Leptinotarsa Decemlineata)

Adults are hard-shelled, with alternating black and yellow stripes, they are 3/8 inch long, and are frequently found on young plants, especially in the spring. Larvae are soft-bodied, humpbacked, pinkish-red grubs with two rows of black spots down each side of the body.

Hosts

All solanaceous crops (eggplant, pepper, potato , tomato), especially eggplant and potato.

Lifecycle

CPB overwinter as adults in plant debris. They emerge in mid-spring and lay bright orange eggs on the undersides of host plant leaves. Larvae hatch, feed on leaf undersides and then move to upper leaf surfaces. There are several generations per season.

Controls

Type Instruction
Cultural Deep straw mulch around susceptible solanaceous plants has been shown to suppress the first generation of Colorado potato beetle adults and larvae in late spring/summer.

Research with living mulches of rye/vetch in row middles mowed and left to dry, must cover young plants. As the plants grow above the mulch level, they are susceptible to second generation Colorado potato beetle damage.
Biological In USDA WA study, control using Beauveria bassiana was inadequate until potato plants grew enough to cover bare soil in the row. Beauveria, the biological control fungus, requires high humidity for germination and infection.

The two-spotted stinkbug, Perillus bioculatus, is a good predator of Colorado potato beetle. Five consecutive releases of the bugs, starting when eggs were first present, maintained plots in New Brunswick, Canada, virtually free from Colorado potato beetle.

This stinkbug has been reported feeding on Colorado Potato Beetle in Western Montana.
Chemical Spinosad, Neem Extract or Pyrethrin.
Conifer Seed bug (Leaffooted Bugs)
Conifer Seed bug (Leaffooted Bugs)
Conifer Seed bug (Leaffooted Bugs)

Conifer Seed bug (Leaffooted Bugs)

(Leptoglossus Occidentalis)

They are reddish brown to a dark gray color with light markings on their abdominal margins. The hind tibia is broad and flat (hence the name leaffooted bug). They range in size from 5/8 to 3/4 inch long.

Hosts

Primarily pines, douglas-fir, and dogwood; occasionally other plants.

Lifecycle

Adults overwinter in a sheltered site (frequently in nearby homes). In spring they move to trees and feed on the male flowers and year-old cones. In late spring, the females lay eggs in small groups glued to needles and leaves. The immature stages (nymphs) feed on seeds throughout the summer and mature in late summer. As adults they continue to feed on seeds until moving to a protected shelter in the fall.

Controls

Type Instruction
None necessary.
Cooley Spruce Gall Adelgid
Cooley Spruce Gall Adelgid
Cooley Spruce Gall Adelgid
Cooley Spruce Gall Adelgid

Cooley Spruce Gall Adelgid

(Adelges Cooleyi)

On spruce, distinctive pine-cone-shaped galls develop on new growth. Greenish-gray aphids, covered with a fine powder of wax, are found within the chambers of the gall. White, woolly aphids are found on douglas-fir and spruce buds in the spring. When infestations occur on developing needles, symptoms may include yellowing and twisting of needles, and sooty mold from the honeydew that the insects secrete.

Hosts

Spruce, Douglas-Fir.

Lifecycle

Woolly, white nymphs overwinter on the lower surface of needles and near buds. In late spring, large egg masses are laid. Eggs hatch in about 20 days and nymphs move to twig tips to feed on the new needles. Nymphs are full grown in mid-summer and produce a generation of new insects that are both winged and wingless. The wingless form remains on the douglas-fir for a second generation. The winged forms fly to spruce to complete their cycle. On spruce, winged adults lay eggs that hatch into nymphs which overwinter at the base of spruce needles. Nymphs resume feeding in the spring and lay eggs on the underside of spruce twigs. These eggs hatch at bud break. As the aphids feed on the needles, a greenish-purple, cone-like gall envelopes them. Aphids crawl out of the cracks in the drying gall and molt to a winged adult stage in late summer. These adults migrate back to douglas-fir.

Controls

Type Instruction
Mechanical Pruning out galls is ineffective.
Chemical Neem and/or insecticidal soap aimed at the woolly, white aphid stage on spruce or douglas-fir in the spring, just as new growth starts to elongate. Repeat applications may be required.

Fall applications of soil applied imidacloprid.
Corn Ear Worms
Corn Ear Worms
Corn Ear Worms
Corn Ear Worms

Corn Ear Worms

(Helecoverpa Zea)

Adults are light gray moths with dark, irregular lines on their wings. Larvae are 1/8 to 1- 1/2 inch long; they are yellow/white to green with brown heads and longitudinal white bands.

Hosts

Beans, corn, peppers, tomatoes.

Lifecycle

Adult moths usually cannot overwinter in Montana. They migrate from the south and arrive in June or July. The moths lay eggs on or near the silks of corn. On other vegetable crops, eggs are laid on leaves near the developing fruits. After 2-5 days, larvae hatch and tunnel into the ear. Four weeks later they are ready to pupate in the soil. Pupation takes 10-14 days. There are generally 2 generations a season.

Controls

Type Instruction
Traps Blacklight traps catch male and female moths; pheromone traps catch only the males. Both traps are most effective as indicators of population levels.
Mechanical Use floating row covers, being sure to remove them when plants bloom so that pollination is not hindered. (Remay has been shown to be the most effective type of floating row cover for these types of pests.)
Botanical Spray pyrethrin in the evening.

NOTE: Minute pirate bugs and damsel bugs feed on eggs. On tomatoes and peppers Bacillus thuringiensis is effective as a spray.

FOR CORN: Injecting mineral oil into the silks after silks begin to brown can control caterpillars.
Biological Scout your plants every 2 to 3 days; apply Bacillus thurengiensis (BtK) in granular or ES (emulsifiable suspension) form if 20% of leaves have "shot holes" in them, being particularly attentive to the undersides of the leaves. (BtK is most effective on small larvae, 1/4 to 3/4 inch long, in their first instar.)
Corn Root Worm
Corn Root Worm
Corn Root Worm
Corn Root Worm

Corn Root Worm

(Diabrotica SPP.)

The most common local variety is the Western corn root worm. Larvae are white with brown heads, 1/2 inch long and slender. Adults are 1/4 inch long, yellow/tan with three black stripes.

Hosts

Corn and related crops.

Lifecycle

Adult beetles are present from July through September. There is one generation per year. Larvae hatch in June from eggs laid at the base of host plants the previous fall.

Controls

Type Instruction
Cultural Additions of organic matter have been shown to decrease root worm populations through increased egg predation. Do not plant corn in the same place for 2 years. Adult beetles can be hand picked.
Chemical Lamba-cyhalothrin (Spectracide Triacizade once & Done Insect Killer), cyfluthrin, permethrin.
Mechanical Use floating row covers. REMEMBER to remove the row covers after corn begins to tassel so that good pollination may occur.
Cottonwood Borer
Cottonwood Borer
Cottonwood Borer

Cottonwood Borer

(Plectodera Scalator)

The adult is a large beetle, from one to one and a half inches long. They are boldly patterned with white and black checkered markings on the wing covers. Larvae are typical round headed borers, legless elongated grubs.

Hosts

Cottonwood, other poplars and willow.

Lifecycle

Adults are active in late spring or early summer, and feed on tender young shoots. This adult feeding often causes the shoots to break, shrivel, and turn black. Eggs are then deposited in pits chewed in the bark at the base of the tree. larvae hatch and feed in the phloem, progressing downward into larger roots during their first fall. Larvae spend the secound summer feeding in galleries at the tree base. The life cycle requires two years to complete.

Controls

Type Instruction
Cultural Most borers attack only trees that are stressed due to drought, injury or disease. Consequently, any means of promoting vigorous tree growth should be considered the primary approach for borer management.

Maintaining steady, adequate moisture is most critical to developing tree defenses to borers.
Cottonwood Leaf Beetle
Cottonwood Leaf Beetle
Cottonwood Leaf Beetle
Cottonwood Leaf Beetle

Cottonwood Leaf Beetle

(Chrysomela Scripta)

The cottonwood leaf beetle is a light tan, oval beetle marked with black spots and is about 3/8 inch long. The larvae are black, worm-like grubs with whitish spotting as they age.

Hosts

Cottonwood, willow and occasionally other Populus species (aspen, poplar).

Lifecycle

The cottonwood leaf beetle overwinters as an adult in protected locations near cottonwood and willow trees. As leaves emerge, adults move back to the trees, feed on the tender twigs, and skeletonize the new leaves. After a few weeks, females lay eggs in clusters of a dozen or more on the undersides of leaves. Young larvae feed and skeletonize the leaf. They pupate attached to the leaf in early summer and produce a second generation.

Controls

Type Instruction
Chemical f >50% of leaves are infested, spray Neem or Spinosad.
Cucumber Beetles
Cucumber Beetles
Cucumber Beetles
Cucumber Beetles

Cucumber Beetles

(Acalymma & Diabrotica SPP.)

There are two main species of cucumber beetles in our area: Striped and Spotted. Striped cucumber beetle ( Acalymma vittatum)adults are 1/5 inch long, yellow, and have a black stripe. Spotted cucumber beetle (Diabrotica undecimpunctata)adults are about the same size, but are greenish with twelve spots on their back.

Hosts

Cucurbits (cucumber, squash), peas.

Lifecycle

Cucumber beetles overwinter as pupae in woody, weedy areas. They emerge in the spring. Adults lay eggs at the base of host plants; larvae hatch and feed on roots in the soil for about 1 month. There may be two generations per season. It is important to control these pests because they can be carriers of bacterial wilt disease.

Controls

Type Instruction
Cultural Grow resistant varieties, when possible.
Traps Unbaited yellow sticky traps and traps baited with volatile cucurbit floral extracts, known as TIC (trimethoxybenzene, indole, and trans-cinnamaldehyde) have been shown to trap cucumber beetles. You can make a similar product yourself: Save dried squash fruits. Powder them in the food processor. Bait your own yellow sticky traps with the powder.
Mechanical Floating row covers are effective in controlling beetle access to your plants. Remove covers, however, when plants are flowering so that good pollination may occur.
Biological Ground beetles and spiders have been reported to reduce densities of striped cucumber beetles. In fact, spiders increased cucumber yield by 25% in a study at the University of Kentucky. Mulch plants with straw to encourage ground beetles and spiders.
Chemical Pyrethrins **Pesticides can injure cucurbits. Be sure foliage is dry at the time of application.
Curly Top (Virus)
Curly Top (Virus)
Curly Top (Virus)

Curly Top (Virus)

(genus Curtovirus)

This disease is viral. It causes dwarfing and leaf curl and yellowing; death will occur if very young plants are infected.

Hosts

Beans, Chard, beets, peppers, spinach, tomatoes, cucurbits (cucumber, squash), watermelon.

Lifecycle

Curly top is spread by beet leafhoppers which ingest the disease from infected plants. Virus is NOT seed born; it overwinters in perennial weed hosts.

Controls

Type Instruction
Control leafhoppers. Remove diseased plants immediately. Use resistant cultivars when possible.
Cutworms
Cutworms
Cutworms

Cutworms

(Noctuidae SPP.)

There are many species of cutworms. The larvae of most are 1- 1/4 to 1- 3/4 inches long; adults are gray/brown moths.

Hosts

Most young vegetable plants.

Lifecycle

There is generally one generation per year. Larvae feed at night and hide during the day. Moths are present May through June. Eggs are laid in late summer in weedy areas and hatch immediately. Our most common cutworm overwinters as a developing caterpillar. In the spring, these caterpillars feed on seedlings or young transplants.

Controls

Type Instruction
Cultural Till gardens in early spring or late fall to expose cutworms. Use transplants and protect with cardboard or plastic collars.
Biological Ground beetles, rove beetles, spiders, toads and snakes feed on cutworms. Check for cutworms at night with flashlight and apply granular forms of Bt mixed with bran. Bt sprays are ineffective.
Chemical Carbaryl mixed with bran baits.
Traps Black light traps used in the evening when the adult moths are flying, traps both males and females. Pheromone traps may be used to trap males. Both types of traps are effective mainly as indicators of population numbers.
Cytospora Canker
Cytospora Canker
Cytospora Canker
Cytospora Canker

Cytospora Canker

(Valsa SPP., Leucostoma SPP.)

Symptoms vary depending on host and species of Cytospora. Cankers are usually irregular in shape and elongate when they appear on limbs and trunks. Discoloration of the outer bark may be yellow, brown, red-brown to gray or black depending on the host plant affected. Pimple-like fruiting structures (pycnidia) often develop in the canker areas. Under moist conditions, pycnidia ooze orange, thread-like spore tendrils. On aspen trees, the substance that oozes from the canker is in a liquid form; on cherry and plum trees, it is gummy. On spruce, dying or dead branches can indicate canker development. Older branches are more susceptible than younger ones. Lesions appear as sunken areas surrounded by swollen callus tissue. Small black fruiting structures may be evident on the canker; however, large amounts of clear amber resin can flow from the infected areas and may obscure the canker location.

Hosts

Apple, Ash, Aspen, Birch, Boxelder, Cottonwood, Elm, Linden, Honey Locust, Maple, Mountain Ash, Oak, Poplar, Sumac, Willow, Spruce, and stone fruits.

Lifecycle

The fungus overwinters in cankered bark. Spores are dispersed by rain, wind, insects, or birds. Infection occurs only through bark wounds, dead tips of twigs, or branch stubs when temperatures are 70 - 80° F. and weather is humid. The fungus grows in the bark until limited by the defense processes of the tree. During periods of active tree growth fungal growth is temporarily inhibited. Fruiting bodies form in the infected bark to complete the life cycle. Drought-stressed trees are more susceptible.

Controls

Type Instruction
Cultural • Prune in late spring after trees have leafed out; pruning wounds heal more rapidly at this time.

• Prune at least one foot below any discoloration. Disinfect your pruners between cuts.

• Prune on a dry day. Avoid overhead irrigation.

• Avoid excessive nitrogen fertilization.Use white reflective paint on young trunks to reduce sunscald wounds.

• Paint the southwest side of tree trunks with white latex paint to avoid winter injury.
Biological The Doromaki procedure is commonly practiced in commercial Japanese orchards. In the spring, cankers are packed with a paste of wet soil (1" thick) from the orchard floor. Vinyl film is wrapped around the packed canker to retain moist soil on the canker. In dry climates the soil may have to be sprinkled to retain moisture during the hot dry months of July and August. The vinyl film is removed the next spring and the soil pack is removed. Trichoderma spp. (Planters box) can be painted onto the cankers and kept moist with the Doromaki procedure.
Damping Off
Damping Off
Damping Off

Damping Off

(Pythium, Rhizoctonia, and other fungi)

Seeds decay before emergence and seedlings fall over at the soil line and die. The disease causing fungi are common in garden soils.

Hosts

Seeds and seedlings of many garden plants.

Lifecycle

Overwinters in plant debris and can survive on seeds. Excessive moisture encourages the disease.

Controls

Type Instruction
Biological Apply as a seed treatment (dust) and/or as a soil drench: Streptomyces griseoviridis (Mycostop); Burkholderia cepacia (Deny); Bacillus subtilis QST 713 (Rapsody); or Gliocladium virens (Soilguard).
Cultural Plant seeds under temperature conditions that favor rapid germination, or pre-sprout seeds before planting outside. Water plants in the late morning to maximize drying conditions. Give plants as much air and light as possible.
Chemical Use fungicide treated seed or apply copper sulfates as a seed treatment (dust) or soil drench.
Diamondback Moth
Diamondback Moth
Diamondback Moth

Diamondback Moth

(Plutella xylostella)

Larvae are greenish-yellow, 5/16 inch long, pointed at both ends and covered with fine black hairs. They are very active and wriggle vigorously and drop from plants when disturbed. Adults have generally gray wings which, when folded over the body, show a series of white diamond patterns on the back. Caterpillars feed on leaves.

Hosts

Cabbage family plants (cabbage, cauliflower, brussels sprouts, broccoli, kohlrabi, kale).

Lifecycle

Adult moths overwinter under cover; they emerge early in spring to mate and lay eggs. Larvae hatch to feed on the undersides of outer leaves, then pupate in a loose cocoon. The cycle from eggs to adults takes only 4-6 weeks. There are usually several generations per season.

Controls

Type Instruction
Biological Check plants weekly as soon as they are planted. Spray if you find 1 worm per 2 plants. Beauveria bassiana (mycotrol) reduced diamondback moth larvae on cabbage transplants in the field. Multiple applications improved performance.

Bt is not particularly effective on this worm; use only when larvae are small and add 1-2 Tblsp/gal of insecticidal soap.

Wasps parasitize these worms. Spiders and damsel bugs feed upon both eggs and young.
Chemical planted. Spray if you find 1 worm per 2 plants. Beauveria bassiana (mycotrol) reduced diamondback moth larvae on cabbage transplants in the field. Multiple applications improved performance.

Bt is not particularly effective on this worm; use only when larvae are small and add 1-2 Tblsp/gal of insecticidal soap.

Wasps parasitize these worms. Spiders and damsel bugs feed upon both eggs and young.
Neem or Spinosad.
Douglas Fir Beetles
Douglas Fir Beetles
Douglas Fir Beetles
Douglas Fir Beetles

Douglas Fir Beetles

(Dendroctonus pseudotsugae)

Adults are 1/6 to 1/4 inch long, dark brown to black with reddish wing covers. Larvae are found within galleries under the bark. They are long, gray, legless grubs with dark heads.

Hosts

Douglas Fir.

Lifecycle

Flight occurs May through June. A second attack occurs in mid September. Life cycle is 2 to 3 years.

Controls

Type Instruction
Cultural Avoid injury to trees. Prune in late winter and remove slash as soon as possible. Mulch conifers with 1 - 3" of composted bark mulch. Keep well watered during July and August, and thin out overcrowded stands of conifers.
Pheromones Douglas-fir beetle communicate via chemical messages, called pheromones, and can recruit other beetles by emitting a specific aggregation pheromone. As the tree becomes too full to sustain more beetles, they switch to an anti-aggregation pheromone, essentially sending a no vacancy message to new arrivals. This chemical(MCH) has been commercially synthesized and can be used to protect individual trees from attack.
Downy Mildew
Downy Mildew
Downy Mildew

Downy Mildew

(Peronospora effusa)

Downy mildew is caused by a fungus which is active during cooler weather, especially temperatures around 46° F. Temperatures between 46 - 60° F. accompanied by rain or high humidity (85%) promote infection. During periods of high humidity, a graysish moldy growth appears on the leaf's underside. Leaves turn yellow then black and rapidly rot in wet conditions.

Hosts

Broccoli, cauliflower, cabbage, Cucurbits (cucumber, squash), lettuce, onion, pea, spinach.

Lifecycle

The fungus overwinters in plants, on seeds, and in the soil. First spores occur in the spring after exposure to water for several hours.

Controls

Type Instruction
Cultural Grow tolerant or resistant varieties. Allow good air circulation by thinning and controlling weeds. Manage overhead irrigation so that plant surfaces have time to dry before cool evening temperatures, or use soaker hoses, drip irrigation. Rotate your crops on a three year rotation.
Chemical Spray several times a week throughly covering the entire plant. Spray neem, potassium bicarbonate, or copper at the first sign of disease and repeat if weather is wet. Caution copper can cause phytotoxicity at high rates.
Dutch Elm Disease
Dutch Elm Disease
Dutch Elm Disease
Dutch Elm Disease

Dutch Elm Disease

(Ophiostoma ulmi)

The first evidence of fungal infection is wilting of the upper branches. Leaves turn yellow, wilt, then brown, but remain on the branches. Eventually the entire tree wilts and dies. Death can occur in several weeks or several years. When bark on infected 1" diameter branches is peeled back, light to dark brown streaks or discoloration in the wood indicates a vascular infection.

Hosts

All species of native and non-native elms. Siberian and Chinese elms are much less susceptible.

Lifecycle

This fungus is spread from diseased elms via inset vectors or through root grafts. European elm bark beetles and native elm bark beetles (Scolytus spp.) are vectors of this disease. The beetles breed in trees or logs infected with the fungus. Sticky fungal spores adhere to the insect's body and are carried to healthy trees. Beetles then feed on and infect healthy trees. The fungus invades the water-conducting vessels and can infect the roots of a large tree in the first season. The fungus proliferates in the roots and then ascends the trunk in a wave of systemic infection that kills parts of or the whole tree.

Controls

Type Instruction
Cultural Do not prune in the spring! Spring pruning attracts the beetles that spread Dutch elm disease. There are now resistant cultivars available including: 'Cathedral', 'Delaware', 'Homestead', 'Frontier', 'Pioneer', 'Regal, 'Sapporo Autumn Gold', 'Independance', 'Valley Forge', 'New Horizon', 'New Harmony' and 'Patriot'. The 'American Liberty' series are not as resistant as the above cultivars.

Maintain tree vigor and health through proper management through the growing season.
Chemical There are reports that tree injections of fungicide have prolonged the lives of infected trees. Injections must be repeated over the life of the tree ( possibly every other year). Fungicidal injections (propaconazole, thiabendazole) are useless if the tree shows 25% or more dieback due to the disease.
Earwig
Earwig
Earwig

Earwig

(Forficula auricularia)

Earwigs are about 3/4 inch long, dark reddish-brown, and have two long pinchers on the rear. Although able to fly, they rarely do.

Hosts

Decomposing organic residue; found on fruit, flowers and corn ears.

Lifecycle

Earwigs are one of the only insects that care for and rear their young. Most of their hunting/foraging is done at night while their days are spent hiding in cracks and crevices.

Controls

Type Instruction
Cultural In spite of their appearance, earwigs are harmless to humans. In fact, if you can tolerate them, they are beneficial insects in the yard and garden because they attack pests such as mites and aphids. On occasion, they will eat small holes in the leaf margins of plants, such as radishes, and they will sometimes damage new growth on plant seedlings. Earwigs are frequently blamed for damage that is actually being caused by slugs, cutworms, snails, or other pests. To be certain which pest is causing the damage, several nighttime checks with a flashlight would expose the culprit.
Botanical Insecticidal soap containing pyrethrum is an effective formulation for controlling earwigs; however, the soap must come in direct contact with the insect so spray it directly on them. Soap that does not come in direct contact will have no effect, nor will it leave residues to control the insects.
Mineral Diatomaceous earth and silica aerogel may be used to minimize populations indoors.
Mechanical Trap earwigs by laying down rolled up newspapers in their area. (Earwigs have a habit of crawling into small places to hide.) Each day, shake the insects from the rolled paper into a bucket of soapy water to kill them. You can also trap earwigs by placing 1/2 inch vegetable oil in shallow cans such as tuna or cat food. Place several cans around the problem area and empty periodically.
Elm Leaf Beetles
Elm Leaf Beetles
Elm Leaf Beetles
Elm Leaf Beetles

Elm Leaf Beetles

(Pyrrhalta luteola)

Feeding adults are yellow-green beetles, 1/4 inch long with a dark stripe down the center of their bodies. Overwintering adults are more green in color. Larvae are black with lateral yellow striping, 1/4 inch long, soft-bodied grubs. Pupae are bright yellow.

Hosts

Elm.

Lifecycle

The yellow-green adult beetle overwinters in protected areas, including nearby buildings. In late spring, beetles emerge and move to elm trees to mate and lay eggs. Females lay masses of bright yellow eggs that are attached to lower leaf surfaces. Larvae hatch after 10-14 days and feed for about 3 weeks. They then crawl down the tree in search of pupation sites. Most pupate at the base of the tree, or in the folds of bark furrows. Adults emerge in 10-15 days and reproduce to begin a second generation.

Controls

Type Instruction
Cultural Aerate soil around elm trees, mulch with wood chips or composted bark 2-3 inches deep.
Chemical Neem, Spinosad and oil sprays can control ELB larvae and are reportedly less toxic to lady beetles than soap, carbaryl, or acephate (Kyhl 1998).
Monitoring Check for worm-like grubs in late May or early June. Treatment is not required unless trees are 40% defoliated and/or 50% are infested with beetle larvae. It is best to treat when larvae are newly hatched.
Biological There are many natural enemies of elm leaf beetle, including several parasitic wasps, spiders, ground beetles, lady beetles, and predaceous plant bugs .

Beauveria bassiana and parasitic nematodes (Heterorhabditis spp.) sprayed on the soil surface beneath elm trees reduced elm leaf beetle pupae by 75% in a Minnesota study . In Montana, apply nematodes or Beauveria in June and keep soil moist.
Engraver Beeltes
Engraver Beeltes
Engraver Beeltes

Engraver Beeltes

(Ips species)

Adults are 1/6 to 1/4 inch long, dark brown to black with reddish wing covers. Larvae are found within galleries under the bark. They are long, gray, legless grubs with dark heads.

Hosts

Pine and sometimes spruce.

Lifecycle

Overwintering adults emerge early in the spring and infest slash or weakened trees. They bore into the bark and constuct "Y" or "H" shaped egg galleries, pushing the boring dust out of the entrance hole as they work. Eggs are laid along the gallery and young larva soon hatch and begin tunneling small lateral galleries that lightly etch the sapwood. From two to four generations of these beetles may develop per year.

Controls

Type Instruction
Traps Pheromone-baited traps effectively lure beetles from slash piles and reduce the likelihood that they will attack surrounding trees. Traps must be placed before the second generation of beetles fly. Hang traps from non-host trees or at least four feet from host species.
Chemical To protect high value trees, Carbaryl can be sprayed preventatively.
Avoid injury to trees. Prune in late winter and remove slash as soon as possible. Mulch conifers with 1 - 3" of composted bark mulch. Keep well watered during July and August, and thin out overcrowded stands of conifers.
Eriophyid Mites
Eriophyid Mites
Eriophyid Mites
Eriophyid Mites

Eriophyid Mites

(Family Eriophydae)

Eriophyid mites are minute, microscopic mites that feed on plants. They are elongate in form, often somewhat carrot-shapped, and are unique among mites in having only two legs.

Hosts

Lifecycle

Eriophyid mites usually overwinter as fertile females that hide under bud scales or other protected sites on their hosts. Slightly different forms involving both sexes are present during the growing season with several overlapping generations present.

Controls

Type Instruction
Treat with horticultural oil as the first buds break in the spring. Dormant bud oil sprays may not be particularly effective. If eriophyid mite feeding has been heavy (>50% of leaves damaged), you might consider a second horticultural oil or insecticidal soap application when the first leaves begin to expand. Most woody species in Missoula have shown no detrimental effects from heavy eriophyid mite infestation during a five year monitoring period.
European Corn Borer
European Corn Borer
European Corn Borer
European Corn Borer

European Corn Borer

(Ostrinia nubilalis)

Adults are pale yellow moths, 1 inch long, with dark bands on their wings. Larvae are pink/grey with brown heads and are about 1/2 to 1 inch long.

Hosts

Beans, Corn, peppers, rhubarb.

Lifecycle

This pest overwinters as a full-grown caterpillar in plant debris. Pupation occurs in the spring. Moths lay eggs which hatch in 10 days. The young borers enter plant tissue, feed for 2-3 weeks, then pupate. There are 2 generations per year.

Controls

Type Instruction
Traps Blacklight traps catch male and female moths; pheromone traps catch only the males. Both traps are most effective as indicators of population levels.
Mechanical Use floating row covers, being sure to remove them when plants bloom so that pollination is not hindered. (Remay has been shown to be the most effective type of floating row cover for these types of pests.)
Biological Scout your plants every 2 to 3 days; apply BtK in granular or ES (emulsifiable suspension) form if 20% of leaves have "shot holes" in them, being particularly attentive to the undersides of the leaves. (BtK is most effective on small larvae, 1/4 to 3/4 inch long, in their first instar.) See Bacillus thuringiensis.

FOR CORN: Spray directly to leaf whorls, and to silks after they have wilted. Apply Dipel (Bt) at 1 lb/A or Xentari at 1.5 lb/A. For late plantings, apply Xentari once at tassel; hand apply a corn oil/Bt mix directly to corn silks. Apply any of the various horticultural oils to ear tips 4 - 5 days after the silks wilt to discourage worms already present. See Bacillus thuringiensis.
Botanical Spray Spinosad or pyrethrin in the evening.
Fairy Ring
Fairy Ring
Fairy Ring

Fairy Ring

((Marasmius spp)

Fairy rings are reported to be caused by many (60) different soil-inhabiting fungi. These fungi may cause the development of rings or arcs of deep green grass. The dark green circles are the result of fungi colonizing the soil, leaf litter. dead tree roots or thatch. The break down of organic matter by fungal activity releases nitrogen. This stimulates the grass on the outside of the ring, causing it to grow taller and darker than surrounding grass. Dead grass sometimes is inside the ring or adjacent to the ring of dark green grass. The band of stimulated grass is often associated with the fruiting bodies of the fungi. Mushrooms typically grow in the ring, are sometimes poisonous and are best picked and disposed of if young children frequent the area. Removing these fruiting bodies does not weaken the fungus.

Hosts

Turf, lawn, grass.

Lifecycle

Fairy rings start from a piece of mycelium or spore. The uniform outward growth of the fungus results in the development of rings. Changing soil types, the fungus involved, condition of the turf, abundance and type of organic matter and obstructions all affect this radial growth. Fairy rings encountering each other in their development will typically produce a scalloped effect of stimulated or dead grass.

Controls

Type Instruction
Cultural Turf subjected to extreme drought stress is more susceptible to problems from fairy ring. Top dress ring with humus builders (finished compost). Fertilize and water area well. Encourage water percolation by plunging a garden fork into the soil five or six inches deep around the ring and watering well. You may also remove the soil to a depth of one foot and wide enough to extend at least two feet on either side of the fairy ring. Replace this soil with non-infected soil or finished compost and reseed or lay sod. Fairy Rings does not destroy turf so it can also be ignored.
Chemical None available. The applications of fungicides is not a reccommended control option. The use of pesticides may increase the incidence of fairy rings by destroying saprophytic bacteria and fungi which compete with the fairy ring fungi.
Fall Webworm
Fall Webworm
Fall Webworm
Fall Webworm

Fall Webworm

(Hyphantria cunea)

The mature caterpillar is yellowish to tawny brown in color with a dark stripe down the back and rows of distinctive orange-yellow tubercles on each side. The body is covered with tufts of long, silky gray hairs. The adult moth is satiny white with long soft hair and may have brown or black spots on the wing. Wingspan is about 1-1¼ inches long.

Hosts

Apple, cottonwood and cherry are the most common hosts, but over 100 species of hardwood may be affected.

Lifecycle

The fall webworm overwinters as a pupa in a light colored cocoon on the ground or under bark. In late spring/early summer adults emerge and lay eggs. Females deposit eggs on leaves in masses of 300 to 400. Eggs hatch in about 10 days. They feed gregariously and spin lightly woven webbed tents which contain the leaves on which they feed. The webs expand as the larvae grow and can reach several feet in diameter by late summer. The larvae mature in the late summer/early fall when they wander from the host tree to search for a protected location to pupate.

Controls

Type Instruction
There are many insect and bird predators. Remove and destroy nests. Bt(Bacillus Thuringensis) is effective on young, smaller larvae. Spinosad and Neem extract is also effective on webworms.
Fir Broom Rust
Fir Broom Rust
Fir Broom Rust

Fir Broom Rust

(Melampsorella caryophyllacearum)

This rust causes upright, compact witches' brooms that bear annual yellow needles. Fir broom rust casues marked loss of chlorophyll and annual casting of all broom needles. Infected branches and stems become swollen at the base of a broom into a spindle-shaped or nearly round gall. The bark on old swellings usually dies and becomes cracked, and open cankers may develope. On the leaves of the alterante host, yellow-orange spores are produced.

Hosts

Affects many species of true firs. Requires alterante hosts in the Caryophyllaceae family including chickweed, sandwort and starwort.

Lifecycle

The fungus lives systemically and perennially in both hosts and may overwinter in either host. In fir, buds and emerging twigs are infected in the spring by spores produced on the alternate host, and the fungus invades the young shoots and induces the formation of witches' brooms.

Controls

Type Instruction
Infection of fir reqires moist and temperate weather conditions and synchrony between spore release and shoot developement. Trees bearing stem cankers or brooms may be pruned out of trees. Removal of the alternate host will help reduce further infections.
Fireblight
Fireblight
Fireblight
Fireblight

Fireblight

(Erwinia amylovora)

Blossoms first appear water-soaked, then black and shriveled. Blighted twigs curl to form a characteristic "shepherd's crook". Leaves quickly die, blacken, and remain attached to the limb. Infected fruit is shriveled and dried. As the disease progresses, it affects older, larger limbs. Cankers are usually discolored, sunken, and defined by a narrow, raised margin. Amber-colored ooze is usually present at infected buds, twigs, and cankers.

Hosts

Apple, pear, quince, crabapple, cotoneaster, hawthorn, mountain ash, pyracantha, serviceberry, and other species in the rose family.

Lifecycle

Fire blight develops in three phases: Blossom blight occurs when flowers are open with stigmas and petals intact during wet weather >65°F. Canker blight occurs when the fireblight bacteria that overwinters on cankers from the previous year renew growth and infect new healthy bark tissue during wet weather >55° F. Canker blight usually occurs during warm wet weather 1 - 2 weeks after apple trees stop blooming. Shoot blight occurs when bacteria invade the tips of new shoots (the tip and youngest 3 leaves are most susceptible) during wet weather >55° F. Shoot blight occurs after the appearance of blossoms and/or canker blight symptoms when shoots have 10 - 12 leaves. Frost, wind, or hail can worsen fireblight infection.

Controls

Type Instruction
Cultural Prune out and destroy infected shoots and branches 12-15" past any visable discoloration on a hot sunny day. Temperatures above 90°F stop fireblight infection. Remember to sterilize pruners between each cut. Keep irrigation water off of trunks, branches and leaves. Avoid excessive nitrogen fertilization.

Plant resistant varieties.

See Disease Resistant Apple Varieties

See Disease Resistant Crabapple Varieties
Chemical Dormant: Bordeaux mix sprayed as buds begin to break helps prevent infection. Spray after pruning. After bloom: Copper can be sprayed when fireblight infection periods occur. Do not spray copper during bloom.
Biological Streptomycin can be sprayed during bloom if fireblight infection periods occur. Two applications have proven to be more effective than one.

Bacillus subtilis Strain QST 713 is not as effectvie if used early in the bloom season.

(Listen to the Pest Alert Phone Line (258-3820 for information on infection period.)
Flatheaded Borer
Flatheaded Borer
Flatheaded Borer

Flatheaded Borer

(Chrysobothris mali)

Larvae are pale yellow and legless with an enlarged, flattened thorax. Adults are dark olive-gray brown metallic wood boring beetles about ½" long. DAMAGE: Immature stages tunnel under the bark of trunks and larger branches producing a fine sawdust frass. Tunneling may girdle and kill young trees. Injuries are concentrated on the sunny side of trees. Beetles most commonly attack trees suffering sunscald, wounds or drought stress.

Hosts

Deciduous fruit, forest, and shade trees. Ash, Maple and apple are the most common hosts. Arborvitae are attacked by a related species.

Lifecycle

Larvae over winter in host plants. In spring, they pupate and bore holes in the host tree. Adults emerge in late spring and lay eggs in cracks in the bark which hatch into larvae in late summer.

Controls

Type Instruction
Cultural Attacks by flatheaded borers are concentrated around wounds, cankered areas, and on drought-stressed trees. Healthy trees are less attractive to egg laying females. Larvae are often killed by the trees defense system which oozes sap. Dying trees and newly cut wood should not be kept near susceptible trees since large numbers of borers can develop in these materials. Once borers are present in the trunk, digging them out in late summer or early fall is the only control. This is difficult to do without causing additional injury.

Painting tree trunks with a white latex based paint will help reduce sunscald injury.
Chemical Imidacloprid applied as a soil drench in the spring.
Flea Beetles
Flea Beetles
Flea Beetles
Flea Beetles

Flea Beetles

(Multiple Species)

There are numerous species of the flea beetles (4000 species of Phyllotreta in the world). Flea beetle species are fairly host specific in their general feeding habits. Flea beetles are very small, typically 1/15 to 1/6 inch. Characteristically they posses very large rear legs that enable them to jump.

Hosts

Lifecycle

Flea beetle biology is not completely understood. They overwinter as adults in the soil in protected areas. Beetles emerge early in the spring and begin feeding on plants and weeds as soon as daytime temperatures consistently reach 40° F. Depending on weather conditions, there are 1- 4 generations per year. Adults can feed for up to 2 months. They lay eggs on the soil around plants and larvae feed on host plant roots. Except for the flea beetles that feed on potatoes, root feeding generally causes little injury.

Controls

Type Instruction
Cultural Know which flea beetle you have and rotate crops accordingly. For example, if you have flea beetles that feed on broccoli but not solanaceous crops, rotate with potatoes following cabbage family crops. Flea beetles are highly mobile, but you can give transplants a head start by planting susceptible crops where non-susceptible crops grew for 2 previous seasons.

Cover transplants with polyspun fabric row covers (i.e. remay). As long as you are rotating susceptible crops, overwintering beetles should not emerge under the row cover. Row covers will not work if flea beetles have overwintered in the soil beneath the row covers because they will emerge inside the covers.

If you have the kind of flea beetles that feed on broccoli and other plants in the cabbage family, you can intercrop with plants the beetles may prefer, such as radish cultivars like Chinese Daikon, White Gem Radish, and Snow Belle. This technique is called "trap cropping". You can also use mustard varieties such as white mustard, Red Giant, Chinese Southern Giant, and Green Wave Mustards. Important points to consider when using trap crops are:
--There should always be a healthy, growing trap crop or flea beetles will move to the plants you are trying to protect. Regular sowings of trap crops throughout the season are required.
--Don't let your trap crop go to seed; it could become a weed.
--The above trap crops will NOT protect Asian cruciferous vegetable crops, such as Napa cabbage, mustard greens, or arugula.
--Climate and weather during a particular growing season will affect the efficiency of trap crops.
--You might consider controlling flea beetles on the trap crop as beetle populations increase. (See LTO chemical control below.)

Sticky traps (white and yellow sticky card traps) encircling susceptible plantings reportedly catch large numbers of flea beetles, but will not control a large population.

Flea beetles can be vacuumed off crops with a handheld, portable vacuum daily to reduce populations.
Biological Predatory nematodes can be applied to moist soil and watered in afterwards.
Chemical Trilogy 90EC (Neem oil) gave the best results in a CA test.

Pyrethrin provided some control of adult flea beetles.

Plant Wash (a soap-based fatty acid insecticide) also provided some flea beetle control.

Spinosad, may need to be applied several times.
Forest and Western Tent Caterpillars
Forest and Western Tent Caterpillars
Forest and Western Tent Caterpillars
Forest and Western Tent Caterpillars

Forest and Western Tent Caterpillars

(Malacosma disstria & M. californicum)

Both species have similar appearances. Small larvae are black with long hairs and feed gregariously. Mature larvae are dark brown with bluish heads and blue-black sides. There is a row of whitish or yellowish keyhole-shaped spots on the back with patches of fine orange lines. Mature larvae feed singly.

Hosts

Ash, elm, cottonwood, aspen, willow, birch, various fruit trees and hardwoods.

Lifecycle

Tent caterpillars overwinter as eggs in a ring-shaped mass encircling small twigs. Larvae hatch when leaves begin to unfold and feed gregariously for 5-6 weeks. They form silken mats on trunks or branches when they rest during the day. Pupation takes place in mid summer inside cocoons formed on folded leaves, in bark crevices, or other sheltered sites. Moths emerge in late summer and females lay egg masses.

Controls

Type Instruction
There are many insect and bird predators. Remove and destroy nests. Bt (Bacillus thuringensis) is effective on young larvae (< ¾").
Fusarium Wilt-Yellows
Fusarium Wilt-Yellows
Fusarium Wilt-Yellows
Fusarium Wilt-Yellows

Fusarium Wilt-Yellows

(Fusarium oxysporum)

Fusarium is a fungus that affects both seedlings and mature plants. It causes top growth to wilt, yellow and die. Lesions form at plant base or slightly below the soil line. Reddish-brown streaks appear in the root, stems and leaf petioles. The earliest symptom is the yellowing of old leaves, often on only one side of the plant. Fusarium is most prevalent on acid, sandy soils.

Hosts

Broccoli and other brassicas (cabbage, cauliflower, brussels sprouts, kohlrabi, kale); asparagus, celery, cucumber, pea, pepper, potato, radish, tomatoes, and dahlia.

Lifecycle

Fusarium overwinters on seeds and plant debris or in the soil. Spores germinate on susceptible roots through wounds, then spreads through xylem tissues. It is especially active in growing, succulent plants. The optimum temperature for spore production is 80°F.; spread of the disease slows at either extreme. Fusarium remains in the soil for several years, in some cases 10 years.

Controls

Type Instruction
Cultural Use a 5 - 7 year rotation. REMOVE AND DESTROY infected plants. Grow resistant varieties. In general, raise the pH to 6.5 - 7 if soil is acid. Use nitrate rather than ammonium nitrogen. Avoid poorly drained and cool soils.
Preventative Soak seeds (or, crowns, in the case of asparagus) in 1 part bleach to 4 parts water for 2 minutes, then rinse under running water for 1 minute.
Biological Microbial Seed Treatments: Gliocladium virens(Soil Guard), Bacillus subtillus strains(Kodiak, Subtilex NG).
Gall Midges
Gall Midges
Gall Midges
Gall Midges

Gall Midges

(Multiple Species)

Hosts

Lifecycle

Honeylocust podgall midge overwinters in the adult stage near previously infested honeylocust plantings. Adults move to emerging honeylocust buds. Eggs are laid among the emerging leaves, and the larvae feed on the leaflets, causing them to curl and thicken into the pod gall. Larvae become full grown in about 3 to 4 weeks. and pupation occurs in the gall. There are three generations per year. Populations decline in early July.

Controls

Type Instruction
Cultural Prune out infested growths.
Chemical Spinosad or horticultural oil applied as new foliage emerges. May need to be applied several times.
Gall Midges
Gall Midges
Gall Midges
Gall Midges

Gall Midges

(Multiple Species)

Hosts

Lifecycle

Honeylocust podgall midge overwinters in the adult stage near previously infested honeylocust plantings. Adults move to emerging honeylocust buds. Eggs are laid among the emerging leaves, and the larvae feed on the leaflets, causing them to curl and thicken into the pod gall. Larvae become full grown in about 3 to 4 weeks. and pupation occurs in the gall. There are three generations per year. Populations decline in early July.

Controls

Type Instruction
Cultural Prune out infested growths.
Chemical Spinosad or horticultural oil applied as new foliage emerges. May need to be applied several times.
Grasshoppers
Grasshoppers
Grasshoppers
Grasshoppers

Grasshoppers

(Melanoplus spp.)

Grasshoppers are some of the most familiar of all insects, and more than 550 species occur in North America. Grasshoppers damage plants by chewing. Most feeding occurs on foliage, although immature pods and fruit may also be eaten. Bark from twigs is sometimes gnawed, causing girdling wounds.

Additional Information

Hosts

Lifecycle

These species overwinter in the egg stage in the soil. Eggs are laid in pods in the soil during late summer and fall and nymphs begin emerging in April, May and June. Researchers have found that grasshopper hatch often corresponds with the time lilacs are in full to late bloom. Nymphs feed on vegetation for 40 to 60 days before molting into the adult stage. Adults disperse to suitable hosts during the summer and can do serious damage to crops and rangeland. Adults mate in late summer and lay the overwintering eggs. In most areas, eggs are laid in waste areas along roadsides and around field margins, especially in grassy, south-facing areas.

Controls

Type Instruction
Cultural Temperature and moisture are important factors in reducing grasshopper populations. Heavy mortality occurs in the spring if cool, wet weather follows warm weather which causes premature hatching of eggs. In late spring, short periods of hot weather increase the incidence of fungus and bacterial diseases.

The best time to control grasshoppers is during early nymphal development when they are most vulnerable to disease, parasites, predators, insecticides and inopportune weather. Grasshoppers breed and grow in weedy, undisturbed areas like roadside ditches, fence rows, untilled pastures, and in crops that continue longer than a single growing season. After the eggs hatch, a survey of the area helps to ascertain where populations are developing. Optimal control is possible when the insects are still immature and restricted to their breeding areas. Adult grasshoppers are difficult to control, hence preventative management is of the essence.
Late summer tillage discourages females from laying eggs in the ground. Tillage also destroys eggs by exposing them to the weather, predators and parasites. Spring tillage eliminates food sources for the newly hatched nymphs. Fall tillage may not be compatible with the goals of sustainable farming because it reduces winter cover necessary to conserve water and prevent erosion. Spring tillage may be the more (ecologically) sustainable option.

Trap crops (small plantings established within or next to the main crop to draw the pests away and concentrate their populations where they can be destroyed) such as untilled strips of vegetation left after spring tilling, may serve to attract nymphs that are mobile enough to search for food. In summer, to protect crops from migrating populations, uncut strips or trap crops may be left between the crop and the direction where the grasshoppers are coming from. In the case of a market garden, an irrigated "greenbelt" along the perimeter will act as a trap crop when the surrounding vegetation begins to dry up in late summer.

Grasshoppers are drawn to monocultures and dislike nitrogen-fixing crops like peas and sweet clover.

Rotation, cover cropping and other practices that promote bio-diversity make farm habitat more attractive to the host of natural predators and parasites that control localized grasshopper infestations. A survey by the USDA's Grasshopper Control Project in 1938-40 showed that 15% of grasshopper egg pods in western and midwestern states were destroyed annually: 6.9% by flies, 5.6% by blister beetles, and 2.5% by ground beetles.


Domesticated livestock, such as chickens, turkeys, guinea fowl, geese and ducks are good for keeping grasshopper populations in check, although they tend to damage the plants in the garden, too.
Biological A well-known biological control for grasshoppers is Nosema locustae, a naturally occurring protozoan that causes disease and death in crickets and grasshoppers. Spores of the parasite are impregnated into wheat bran flakes and applied by hand. It takes between one and five weeks for the grasshoppers to be infected. Following ingestion, the spore ruptures and activates the disease in the grasshopper. Infected individuals are lethargic and slow, making them easy prey for birds. Nosema locustae is not toxic to birds, animals or other insects. The trade name is Semaspore or Nolo bait.

When using Nosema locustae, growers should locate spring hatching areas. Bait broadcast over these locations will sicken and kill the nymphs. Nosema is effective against adults too but most effective against the second and third instar nymphs. Reports on the success of N. locustae are mixed. It is not a good "rescue" treatment and will not result in instant adult mortality. According to Jerome Onsager, one of the first Nosema researchers at the USDA Rangeland Insect Laboratory in Bozeman, Montana, Nosema was developed as a management tool, not to provide instant control.

The fungus Beauveria bassiana is yet another biopesticide registered for grasshopper control. Beauvaria bassiana (BotaniGard) and spinosad (Conserve SC) reduced grasshopper populations in a CO study. Canola oil added to grasshopper sprays increases mortality because canola oil attracts grasshoppers.

Also in the above CO study, neem (Bioneem and Trilogy) and hot pepper wax reduced feeding. Garlic is reportedly effective too. Garlic spray may be made at home or purchased. Directions for making your own spray are as follows: Soak three ounces of finely-minced garlic cloves in two teaspoons of mineral oil for at least 24 hours. Add one pint of water that has ¼ ounce of liquid dish soap mixed into it. Stir well and strain into a glass jar for storage. Combine one tablespoon of this concentrate with one pint of water to make a spray.
Chemical Baits containing carbaryl can be applied in a more selective manner. Insecticides such as malathion, permethrin, bifenthrin can be use as a contact sprays.
Mechanical Row covers (remay) can be used to cover valuable garden plants.
Grey Mold
Grey Mold
Grey Mold
Grey Mold

Grey Mold

(Botrytis cinerea)

Senescent leaves, fruits, and petals are susceptible. Under cool (60 - 70° F.), moist conditions a soft, brown decay develops, covered by a dense gray to light brown mass of spores. Growth of this fungus is inhibited at temperatures above 89° F.

Additional Information

Hosts

Many vegetables, fruits including strawberries, and flower crops.

Lifecycle

The fungus overwinters on plant debris and organic matter in the soil.

Controls

Type Instruction
Plant on raised beds, maintain low humidity, space plants so foliage dries rapidly, pick fruit as it ripens, and remove dead leaves. Spray at first bloom when humid, cloudy weather persists with captan or neem oil.
Harlequin Bug
Harlequin Bug
Harlequin Bug
Harlequin Bug

Harlequin Bug

(Margantia histrionica)

Adults are flat, 3/8 inch long, shield-shaped stink bugs with red and black spotted markings; nymphs look like adults, but are smaller and more round.

Additional Information

Hosts

Cabbage family plants (cabbage, cauliflower, brussels sprouts, broccoli, kohlrabi, kale).

Lifecycle

Adults overwinter under debris. They emerge in mid-spring and lay eggs by early summer. After hatching, nymphs feed for two months, by which time they are mature. There can be 1-2 generations per year.

Controls

Type Instruction
Cultural Control weeds by removing, or mowing in crops or adjacent areas. Attract native parasitic wasps and flies by planting small-flowered plants.
Botanical Spray with pyrethrin.
Hollyhock Rust
Hollyhock Rust
Hollyhock Rust

Hollyhock Rust

(Puccinia malvacearum)

This fungal disease causes orangish, waxy, rust/reddish raised spots on the underside of leaves and bright orange spots with red centers on the upper surface of leaves and shoots. Severe infections can cause considerable leaf drop.

Additional Information

Hosts

Hollyhock(Alcea rosea).

Lifecycle

The rust fungus overwinters in pustules on plant debris. In the spring, spores produced in the pustules are blown to young hollyhock plants where they initiate new infections.

Controls

Type Instruction
Cultural Sanitation is the key:

• Remove and destroy all infected plant parts.

• During growing season keep infected leaves picked off of plants.

• Remove other host plants: Lavatera, Hibiscus, and other Malvaceae.
Chemical Use with cultural controls. Wettable sulfur at 3 Tbsp/gal is the least toxic option. Daconil (chlorothalonil) or Immunox can be used in home gardens if weather is wet and warm, and the disease was a problem the previous year.
Imported Cabbage Worm
Imported Cabbage Worm
Imported Cabbage Worm
Imported Cabbage Worm

Imported Cabbage Worm

(Pieris rapae)

Larvae are velvety-green with a faint yellow stripe up to 1-1/4 inch long. They are very slow moving. Adults are white butterflies.

Additional Information

Hosts

Broccoli and other cabbage family plants (cabbage, cauliflower, brussels sprouts, kohlrabi, kale), lettuce, radish, rhubarb.

Lifecycle

The adult butterflies are usually active during the months of May and June. Larvae hatch and begin feeding, usually on the outside leaves.

Controls

Type Instruction
Cultural Grow resistant varieties if available. Heavy rainfall helps to decrease worm populations, so overhead irrigation or directed sprays of water can somewhat decrease population levels in the early stages.
Biological Start checking for these worms as soon as you begin to see adults flying around your plants. Spray with Bt(Bacillus Thuringensis) when you find 1 worm per 2 plants. It is most effective on newly hatched, smaller (1/2 - ¾") worms.
Mechanical Cover plants with floating row cover(remay) before butterflies are present.
Chemical Spinosad or pyrethrin can be sprayed on larva.
Ink Spot
Ink Spot
Ink Spot

Ink Spot

(Ciborinia whetzelii)

Ink spot-like spots on crown leaves in early summer; by late summer the spots (sclerotia) drop out of the leaves causing a shothole appearance. Early summer symptoms of ink spot can look like leafminer insect damage with concentric zones that are light and dark.

Additional Information

Hosts

Aspens, cottonwoods and other poplars.

Lifecycle

Ink spot fungi overwinter in forest litter. In spring sclerotia produce stalked, cup-like fruiting bodies (apothecia). Spores are dispersed by wind and rain to infect leaf surfaces. After 2-3 weeks, reddish brown blotches become visible and expand until the leaf is entirely dead. Several weeks later, one to four dark mycelial masses appear (inkspots). These sclerotia will remain on the leaf until late summer then drop to the ground where they will overwinter.

Controls

Type Instruction
Cultural Rake up and destroy infected leaves in the fall. Increase spacing between trees to create better air circulation.
Chemical Fungicides, if applied early enough, can prevent ink spot. Spraying will prevent new infections, it will not cure leaves already infected In an infection is developing on particularly valuable trees, or if there is good reason to believe an infection is imminent, the trees can be sprayed with fungicides. Trees should be spayed at bud break and then two to three times during the growing season at 12 - 14 day intervals. Fungicides are manozeb, chlorothalonil and basic copper sulfate.
Iris Leaf Spot
Iris Leaf Spot
Iris Leaf Spot

Iris Leaf Spot

(Mycosphaerella macrospora)

Mycosphaerella macrospora develop as tiny brown spots which later turn yellow and then run together. When infection is severe leaves may die. Older spots are oval and have grayish centers with red-brown borders. Iris leaf spot is a common disease caused by the fungus Mycosphaerella macrospora (formerly Didymellina macrospora). Wet weather or excessive overhead irrigation creates severe outbreaks of this disease.

Additional Information

Hosts

Iris.

Lifecycle

Mycosphaerella macrospora overwinters on dead leaves and other plant materials. Spores are formed in the spring and are dispersed by wind and rain. They infect leaves directly or through stomata. During wet warm weather the disease cycle may occur many times. Acid soil may intensify the disease. Premature killing of the leaves can weaken the bulb or rhizome causing the gradual death of the entire plant. Although infection is usually confined to the leaves, stems, flower stalks, and buds may become infected during severe outbreaks of this disease.

Controls

Type Instruction
• Remove and destroy dead and infected leaves when they begin to die after Iris has flowered.

• Plant irises in full sun.

• Maintain proper plant spacing to provide good air circulation.

• Rotate plantings.

• Check pH; maintain soil pH above 6. Low pH encourages this disease.

• Apply Chlorotholanil or Spectracide Immunox if infection is severe; add a drop of liquid dish soap as a spreader-sticker to fungicide mixture.
Apply when leaves are 6-8" tall, weather is wet and temperatures >65ºF.
Late Blight
Late Blight
Late Blight
Late Blight

Late Blight

(Phytophthora infestans)

Watersoaked spots enlarge into brown blotches on older leaves first. Leaf undersides may be covered with a gray to white moldy growth. Infected leaves, petioles, and stems shrivel and die. Tomato fruit develops dark, greasy-looking spots that enlarge until the fruit rots. Potato tubers show irregular, slightly depressed areas of brown to purplish skin.

Additional Information

Hosts

Potato, tomato, occasionally eggplant.

Lifecycle

The fungus overwinters on crop debris. At 91 - 100% humidity and optimum temperatures of 65 - 72° F. (cool days plus warm nights), inoculum carried by wind and water infect young plants. When weather is favorable, infection moves so fast that plants appear to have been damaged by frost.

Controls

Type Instruction
Cultural Temperatures above 86° F. decrease infection. Plant resistant varieties when possible. Use Blight-free seed and destroy volunteer plants. Reduce time water is on foliage- water mid morning. For potatoes, keep tubers covered by hilling with soil throughout the growing season.
Chemical Spray copper when weather is humid / wet and temperatures are between 60 and 75° F. Chlorothalonil or a mancozeb-based product are fungicides labeled for late blight.
Leaf Rusts
Leaf Rusts
Leaf Rusts
Leaf Rusts

Leaf Rusts

(Multiple Species)

Additional Information

Hosts

Lifecycle

Wet weather and mild tempertures are required for rust infections. Optimal tempertures range from 64 to 70 degrees F with continual moisture on leaf surfaces for two to twenty four hours. Hot, dry weather will limit rust development.

Controls

Type Instruction
Cultural Rust diseases are managed with sanitation, or removal of fallen leaf debris. Resisant varieties may be available.
Chemical Chemical control is rarely needed, however several fungicides such as Chlorothalonil and Myclobutanil are effective.
Leafcutter Bees
Leafcutter Bees
Leafcutter Bees

Leafcutter Bees

(Megachile species)

Adult leafcutter bees resemble dark, robust honeybees.

Additional Information

Hosts

Rose family plants, ash trees and a wide variety of plants.

Lifecycle

Leafcutter bees are solitary bees. The female cuts leaf disks to create individual thimble shaped rearing cells packed with pollen.

Leafhoppers
Leafhoppers
Leafhoppers
Leafhoppers

Leafhoppers

(Multiple Species)

There are many different types of leafhoppers. Adults are generally tiny, winged, pale green to whitish insects (1/8 inch long). They fly up from underneath leaves when disturbed and are sometimes mistaken for whiteflies. Nymphs are wingless, 1/8 inch, pale green to whitish and resemble fat aphids. Several generations occur per season and populations can build to be quite high on some plants later in the growing season.

Additional Information

Hosts

Lifecycle

Depends on the species.

Controls

Type Instruction
Chemical Best control occurs if you discover an infestation early and treat when nymphs are present, before adults emerge. Insecticidal soap and neem sprayed on leaf undersides in the early morning or later evenings, when leafhopper adults do not move so fast, can provide control if applied every 5 - 7 days. Pyrethrin spray is also effective.
Mechanical Yellow sticky traps can attract and decrease leafhopper populations. Floating row covers over emerging seedlings can help protect from this pest. Shading plants helps to avoid leafhoppers.
Leafminers
Leafminers
Leafminers
Leafminers

Leafminers

(Multiple Species)

Larval leafminers burrow underneath leaf surfaces leaving a visible trail as they eat their way through the leaf. Leafminers can be flies, wasps, moths, or sawflies. Leaves damaged by leafminers have a distinct top and bottom leaf surface that can be pulled apart at the tan-colored blotch or serpentine trail. Inside trails or blotches, you will find a larva or the black, sawdusty leafminer droppings.

Additional Information

Hosts

Ornamental Plants: Lilac, birch, aspen, elm and many other deciduous trees, shrubs, and flowers. Vegetables: Spinach, beans, potato, tomato, onion, pepper, squash, melon, pea, chard, and beet.

Lifecycle

Varies depending on species. Leafmining flys overwinter as a pupa in the soil, emerging in mid spring. The adult fly lays small masses of eggs on the undersides of leaves. Upon hatching the young maggots tunnel into the leaves, where they feed, typically for 2 to 3 weeks. When full grown the cut through the leaf, drop to the ground and pupate into the soil. Several generations maybe completed during the season.

Controls

Type Instruction
Biological There are native parasitoids of leafminers. Avoid general insecticides that kill these parasitoids. In New England, releases of European ichneumonid wasps in the 1970's are now resulting in significant reduction of birch leafminer close to the original release sites.
Chemical Spinosad: apply at 1st larval hatch, when larvae are 1/8" or shorter. Both Spinosad and Neem inhibited feeding and egglaying of leafminers on Chrysanthemum up to 24 hours after application. When 1% neem seed extract was sprayed to runoff on birch tree foliage containing eggs or early instars of birch leafminer, larval mortality was greater than 99% . According to USDA studies in Maryland, neem has some systemic activity against leafminers when applied as a soil drench; neem soil drenches are an option for vegetable leafminers if applied early. Also, Abamectin (Avid).

For large trees soil injections of imidacloprid in late fall/early spring works.
Mechanical Applying row covers as soon as plants emerge may aid in controlling those leafminers which attack vegetable crops; yellow sticky traps are also somewhat effective at trapping adults if pest populations are low.
Leafrollers
Leafrollers
Leafrollers
Leafrollers

Leafrollers

(many species)

Boxelder Leafroller - Adults are ½ inch tan moths; larvae are 1/4 to 3/4 inch, green caterpillars with a dark head. There is one generation per year. Food preferences: Boxelder Fruittree Leafroller - Adults are 1/2 to 3/4 inch moths with a mottled, rusty-brown pattern; larvae are 1/4 to 3/4 inch, pale-green caterpillars with a black head. There is one generation per year. Food preferences: Apple, pear, plum, cherry, raspberry, currant, ash, boxelder, elm, linden, poplar, willow, locust, rose, and oak. Oblique-banded Leafroller - Adults are 3/4 to 1 inch moths with a tan to brown band; larvae are 1/4 - 1 inch, green caterpillars with brown heads. There are two generations per year. Food preferences: Fruit trees and ornamental trees and shrubs.

Hosts

Lifecycle

Our main Montana leafroller, the Fruittree leafroller overwinters as an egg. Eggs hatch into tiny larvae in spring around mid-May. Larvae feed on leaves for about 30 days and then pupate in a rolled leaf or similar shelter. Eight to 11 days later the adult emerges from the pupa. The moths live only about a week, during which time they mate and lay eggs. They fly in May or June for about 3 weeks. Only one generation occurs each year.

Controls

Type Instruction
Botanical Bacillus thuringiensis (Bt-K). Treat newly hatched larvae, before leaves curl. This works best when temperatures are warm (>50ºF)
Biological Several native parasitic insects have provided adequate control of Oblique-banded leafrollers in Wisconsin, including a species of tachinid fly and species of braconid, ichneumonid, and chalid wasps. Spiders, pathogens, and other predators also contributed to oblique-banded leafroller control in a University of Wisconsin study.
Chemical Spinosad - Treat by spraying newly hatched larvae. Pyrethrin sprays targeted at the leafroller before the leave curls. Delayed-dormant oil sprays work on the fruittree leafrollers as they overwinter in egg masses on the tree.
Lilac / Ash Borer
Lilac / Ash Borer
Lilac / Ash Borer

Lilac / Ash Borer

(Podoesia syringae)

The larvae are creamy white grubs with a dark head. Adults are moths that resemble paper wasps. The moth is about 1" long with a wing span of 1-1/2 inches.

Hosts

Ash and lilac

Lifecycle

The borer overwinters as larvae within tunnels under the bark. Adults emerge when temperatures above 60°F. are prevalent in the spring. Cool, cloudy weather may extend the adult flight period. Eggs are laid on bark near wounds or bark cracks. Larvae hatch May through July.

Controls

Type Instruction
Cultural Several parasitic wasps prey on this borer. Prune trees before April since fresh pruning wounds attract egg laying adults. Pheromone traps are available to trap adult moths.
Chemical Trunk sprays of permethrin can be applied 2 weeks after the adults are caught in pheromone traps.
Marssonina Leaf Spot/Blight
Marssonina Leaf Spot/Blight
Marssonina Leaf Spot/Blight

Marssonina Leaf Spot/Blight

(Marssonina populi)

Dark brown flecks with yellow margins scattered over leaf surfaces. Spots later merge to form black blotches. Mature spots have a white center. Often confused with leaf scorch due to drought stress. Severe infection can cause early defoliation and reduce growth.

Hosts

Aspen, cottonwoods, and poplars.

Lifecycle

The fungus overwinters in infected leaf debris on the ground or twigs infected the past year. Infection occurs when spores are released and carried by the wind and rain to developing newly expanded, spring leaves. Secondary infection occurs later in the summer when fruiting from infected leaves produce spores that are blown to adjacent leaves.

Controls

Type Instruction
Cultural Rake up and destroy infected leaves. Keep irrigation water off leaves.
Mineral Spray a copper based fungicide as buds begin to break. If weather is wet and warm, protect developing leaves with sulfur or chlorothonanil.
Melting Out
Melting Out
Melting Out

Melting Out

(Drechslera poae)

Tiny, water-soaked lesions turn purple with straw-colored centers. Leaf spots on grass blades extend across the entire plant killing it. This causes the grass to look thin and yellow in color. Irregular patches of tan to reddish brown turf; resembles dull mower injury.

Hosts

Kentucky bluegrass, annual bluegrass, tall and fine leafed fescues

Lifecycle

Leaf spots followed by melting out occur mainly during cool, humid, overcast periods, usually in spring and autumn.

Controls

Type Instruction
Use resistant cultivars of fescue and bluegrass. Maintain moderate fertility but avoid excessive growth. Water in the morning to wet the soil deeply, but as infrequently as possible without causing stress. Mow grass as high as practical when turf is dry and remove clippings. Remove excess thatch and aerify if needed to provide good drainage.
Mosaic Virus
Mosaic Virus
Mosaic Virus
Mosaic Virus

Mosaic Virus

(many species)

Maize Dwarf Mosaic Virus - Chlorotic spots that elongate on young leaves. Food preferences: Corn Squash Mosaic Virus - Patches of light green or yellowish colored leaf tissue. Food preferences: Cucurbits (Cucumber, squash). Tobacco Mosaic Virus - Yellow/green mottling in plant leaves and/or puckering and distortion of leaves. Food preferences: Cucurbits (cucumber, squash), solanaceous crops (eggplant, pepper, potato, tomato), celery, corn.

Hosts

Lifecycle

Mosaic virus is very persistent. It is spread either through insects or mechanically (such as through infected tools). Infection is rapid, multiplication beginning within minutes. The virus reproduces within the plant cell and disrupts the cell's normal function.

Controls

Type Instruction
Cultural Grow resistant varieties. Control aphids and cucumber beetles which help spread the virus. Pre-soak seeds in a 10% trisodium phosphate solution for 15 minutes.
There is no known cure for this disease. Remove and destroy all infected plants.
Mountain Pine Beetle
Mountain Pine Beetle
Mountain Pine Beetle
Mountain Pine Beetle

Mountain Pine Beetle

(Dendroctonus ponderosae)

Adult beetles are cylindrical, stout bodied beetles, about 1/4 inch long, and brown to black in color. The larvae are white-yellowish, legless grubs with a dark head

Hosts

All native and introduced species of pine.

Lifecycle

Larvae spend the winter under the bark. They feed throughout the spring and then pupate in early summer. Depending on the species of host tree the beetle will emerge in mid to late summer(End of June to Sept.) to attack new host trees. After they mate the female forms a vertical tunnel and lays about 75 eggs. When the eggs hatch, the larvae tunnel away from the egg gallery which produced a characteristic pattern in the wood. Look for pitch tubes and red boring dust in bark crevices and on the ground. Trees in diameter of 4" and over are susceptible to attack. Once infested they usually die. A complex of bluestain fungi that turns the sapwood grayish-blue disrupts the vascular system is introduced into the tree by attacking beetles.

Controls

Type Instruction
Cultural Woodpeckers and clerid beetles feed on Mountain pine beetle adults and larvae. Do not allow trees to become overcrowded. Keep trees watered during July and August. Maintain pH at <6.5; mulch with composted fir or pine bark 1 - 2 inches deep. Remove and destroy infested trees.
Chemical Carbaryl (SL or XLR ) can be applied to tree trunks 30 - 35' high or when trunk diameter reaches 4-5" before June 15 first. One treatment is good for two seasons.
Trapping Anti-aggregation pheromone verbenone is effective if the area's infestation is not severe. Recommended dosage is 2 pouches per tree for individual trees or 20-40 pouches per acre. Apply as close to July 1st as possible.
Needle Casts
Needle Casts
Needle Casts
Needle Casts

Needle Casts

(arious species: for Ponderosa and Lodge Pole Pine - Elytroderma deformans, Lophodermium spp., Lophodermella concolor, Mycosphaerelle pini)

The needles are infected in the spring. Portions (bands), or whole needles turn red-brown in color. Damage is most often found on the lower crown of the tree. Needles are shed 12 to 24 months after infection, depending upon the species. Saplings are usually most severely affected. Tree species attacked can be used as a general indicator of needle cast species. Small black dot-like fruiting bodies may also be present on needles.

Hosts

Ponderosa Pine, Lodge Pole Pine. Douglas Fir and Spruce also host different species specific needle cast diseases.

Lifecycle

Controls

Type Instruction
Cultural When practical, diseased needles that have fallen should be raked up and destroyed. Maintain good tree health: keep trees watered during dry months, but do NOT use sprinkler irrigation (keeps water off of trunk, branches, and needles). Prune where justified since the majority of infections occur in the lower crown.
Chemical Bordeaux Mix or chlorothalonil can be sprayed when new needles begin to elongate in late spring; repeat again in two weeks if weather is wet and warm.
Peach Leaf Curl
Peach Leaf Curl
Peach Leaf Curl

Peach Leaf Curl

(Taphrina deformans)

New spring leaves are thickened, curled, and red or yellow in color. Severely infected shoots die. Infected leaves fall prematurely. Blossoms may shrivel and drop.

Hosts

Peach (other species of Taphrina may affect plums).

Lifecycle

Peach leaf curl over-winters on tree surfaces and buds. Wet, humid weather as leaves emerge in the spring favor new infection. Growth is most rapid at 20 C.

Controls

Type Instruction
Cultural Prune out infected branches/leaves. Rake and destroy infected leaves in the fall. Plant resistant cultivars.
Chemical Spray copper as buds start to swell in the spring.
Pear Psylla
Pear Psylla
Pear Psylla

Pear Psylla

(Cacopsylla pyricola)

Adults are small (1/10 inch), reddish-brown winged insects. Nymphs are flattened, green and scale-like, usually covered by a honeydew droplet.

Hosts

Pear

Lifecycle

Pear psylla overwinter as adults in protected areas (under bark and plant debris on soil) near previously infested trees. They emerge in late winter or early spring and move to the host tree. Yellow-orange eggs are laid as pear buds swell. Hatching nymphs move to feed on tender new leaves. Psyllid nymphs are covered with a honeydew droplet that they produce; as they mature, they lose the honeydew droplet. After molting, adult females lay eggs on new leaves, concentrating on suckers. There are 2 - 3 generations produced during a season.

Controls

Type Instruction
Biological According to work done at the USDA-ARS in Wapato, WA, predatory anthocorid bugs are often effective predators of pear psylla. However, populations of these predatory bugs vary seasonally. Several native plant species are alternate hosts for these predatory bugs. Bitterbrush, Purshia tridentata, is an important alternate host, as are willow and pear species in the spring, alder in early summer, oak and cottonwood throughout the summer, and aspen in late summer through fall. The USDA-ARS work indicates that these psylla-eating predatory plant bugs develop on early season willow, bitterbrush, and pear, then move onto summer hosts to feed on aphids. Other insects such as parasitic wasps, ladybeetles, lacewings, earwigs and minute pirate bugs are natural enemies.
Chemical Use superior-type oil as buds break in spring. Spray insecticidal soap or neem extract as eggs hatch and nymphs begin to feed on expanding leaves in late spring.
Pear Slug - Pear Sawfly
Pear Slug - Pear Sawfly
Pear Slug - Pear Sawfly

Pear Slug - Pear Sawfly

(Caliroa cerasi)

Young larvae resemble a small slug due to the green slime that covers their body. Newly molted larvae are yellow until the slime is secreted. During the last instar the larvae lose their slimy covering and are a light orange color. At this stage they are about 3/8 inches long and have 10 pairs of legs. The adult is a black wasp about 1/5 inch long.

Hosts

Pear, plum, cherry and (occasionally) apple. Also Hawthorn and Mountain Ash.

Lifecycle

The pupa overwinter in the soil, adults emerge in June. The adults lay their eggs in slits on the upper surface of leaves. Eggs hatch and larvae begin chewing small pits in the leaves. There are 2 generations in Missoula, one in June and one in late August.

Controls

Type Instruction
Chemical Spray with insecticidal soap if >50% of leaves have feeding injury.
Cultural Wash off larvae with strong stream of water.
Petiole Gall Aphid
Petiole Gall Aphid
Petiole Gall Aphid

Petiole Gall Aphid

()

Round hollow galls form on leaf petioles. Infested leaves may drop prematurely in late summer.

Hosts

Poplars, cottonwoods

Lifecycle

The petiole gall aphid winters as eggs on twigs of poplar and cottonwoods and produce swellings on leaves in spring. Winged stages fly from these hosts to feed on the roots of various plants during the summer.

Controls

Type Instruction
They are not a serious problem on Populus spp. and control is not necessary for these species.
Phytophthera Root or Crown Rot
Phytophthera Root or Crown Rot
Phytophthera Root or Crown Rot

Phytophthera Root or Crown Rot

(Phytophthora spp.)

The most obvious symptoms of root and crown rot are stunted, yellowing leaves, premature fall coloration and leaf drop, and twig and branch dieback. By the time the foliar symptoms develop, the rot canker may extend halfway or more around the stem of the plant. In early stages, the diseased bark is firm and intact while the inner bark is slimy and may produce a moist, gummy exudate. Later, the affected area becomes shrunken and cracked.

Hosts

Honeylocust, apple and crabapple, raspberry, stone fruits and junipers; other vegetable crops, including asparagus.

Lifecycle

Phytophthera fungal species overwinter as spores in soil or diseased plant material. Species that cause root and crown rots enter host plants near the root collar via wounds or the succulent parts of small roots. Fungal spores move in water and are attracted to the root exudate's from stressed plants.

Controls

Type Instruction
Provide good soil aeration, mulch woody species with 1-3 inches of composted wood bark chips. Plant resistant varieties.

In the case of vegetables, plant in raised beds to provide for good drainage. Keep the soil pH above 6.0.

REMOVE AND DESTROY infected plants, including the roots.
Poplar Borer
Poplar Borer
Poplar Borer
Poplar Borer

Poplar Borer

(Saperda calcarata)

Larvae are large, yellowish, round-headed grubs, 1- 3/8 inch; adults are gray beetles with a central yellow stripe on the thorax and yellow-black-stippled wing covers, 1-1/4 inch long.

Hosts

Aspen, cottonwood, poplars, willow.

Lifecycle

The poplar borer has an extended life cycle that likely requires three years to complete; shorter life cycles may occur in warmer areas of the state. Adult beetles may be present from mid-June through early fall, and feed on bark of young twigs. After mating, females chew pits in the bark and insert eggs. Most egg laying is concentrated in the middle of the tree, particularly near existing areas of infestation. During the first year, the young larvae spend the winter under the bark. In spring, they enter the sapwood and heartwood where they feed for two years, producing large, black, swollen scars on trunks and limbs. Throughout their period of feeding, they maintain an opening to the outside through which they push the boring dust. After the larval stage is complete, they form a chamber under the bark where they pupate and spend the winter.

Controls

Type Instruction
Cultural Individual trees may serve as "brood trees" which can infest other plantings. Removal of these highly susceptible trees should be considered. Most often, large, over-mature trees in open areas are particularly susceptible to attacks by this species. To make trees less susceptible to attack, keep them healthy with proper mulching and watering during the hot summer months.
Chemical Because of the long (probably three year) life cycle, poplar borer is particularly difficult to control. Apply Carbaryl, Permethrin or Cyfluthrin to the trunk in July when adults are active. Application should focus on existing areas of attack in the middle of the tree where egg laying is concentrated.
Biological Insertion of 'borer crystals' (paradichlorobenzene) or injections of insect parasitic nematodes (Steinernema species) into active borer tunnels have given partial control of larvae.
Poplar Vagabond Aphid
Poplar Vagabond Aphid
Poplar Vagabond Aphid

Poplar Vagabond Aphid

(Mordwilkoja vagabunda)

Adults are yellow-green, pear shaped adults, with relatively long antennae and delicate wings. Nymphs are greenish, turning more cream colored as they age. Aphids feeding on new developing leaves cause them to become highly distorted leathery folded leaf galls.

Hosts

Aspen, cottonwoods, and other poplars

Lifecycle

The vagabond aphid uses two hosts during its life cycle. The overwintering stage are eggs laid on bark crevices or old galls on host species. Eggs hatch in the spring and aphids feed on the expanding tips of the twigs. Feeding induces twig tips to form irregularly shaped galls within which the aphid feeds and reproduce. Several generations occur within the folds of the gall. In early summer, winged forms of the aphid leave the gall and fly to a summer host. In the fall, winged stages fly back to the poplar species mate and lay overwintering eggs.

Controls

Type Instruction
Galled leaves tend to remain on trees and may not be visible until after normal leaf fall. Galling is concentrated on the upper third of the tree. Controls have not been identified. Dormant applications of horticultural oils should kill overwintering eggs.
Potato Scab
Potato Scab
Potato Scab

Potato Scab

(Streptomyces species)

Tuber surfaces have areas that are brown, roughened, raised or pitted, and warty-looking.

Hosts

Potato and sometimes red beets.

Lifecycle

Potato scab bacteria survives in the soil in the absence of host plants; it can attack the roots of weeds and other root crops. The potato scab bacteria is inhibited at soil pH higher than 7.4 and lower than 5.4. Optimum soil pH for scab is 7.0. The bacteria invades through lenticels when potato tubers are developing during the first 5 weeks after planting. If potato tubers dry out during this period, they are much more susceptible to scab.

Controls

Type Instruction
Cultural Be careful not to let potato soil dry out during early tuber development. Good moisture from one week before first shoots emerge until eight weeks after emergence can greatly reduce scab severity. Research has shown that the microorganisms surrounding potato tuber lenticels are antagonistic to the scab bacterium under high but NOT under low soil moisture conditions. Mulching with straw (as long as soil has good drainage) may help to maintain higher moisture levels and discourage scab. Resistant cultivars include: 'Superior' (susceptible to verticillium wilt), 'Russet Burbank', 'Pungo', 'Rhinered', 'Onoway', 'Russian Banana', 'Norgold', 'Nooksack', 'Targhee', 'Beltville', and 'Norland'.
Powdery Mildew
Powdery Mildew
Powdery Mildew
Powdery Mildew

Powdery Mildew

(Erysiphe, Sphaerotheca, Phyllactinia, Microsphaera, Podosphaera, or Uncinula spp.)

White, threadlike fungal mycelia give NEW leaves and shoots a powdery appearance. Later, light brown to orange pinhead-sized specks form within the mass of white growth. These tiny dots mature and turn black. These black structures are the overwintering stage.

Hosts

Annual and perennial flowers, esp. roses, lupines, bee balm and tall phlox; woody shrubs and trees, esp. Apple, Ash, crabapple, lilac, caraganna, raspberry and yellow-leafed spireas. For vegetables, cabbage, cauliflower, brussels sprouts, broccoli, kohlrabi, kale), sometimes tomatoes, eggplant, peppers.

Lifecycle

This disease overwinters on leaf debris. Spores germinate in the spring when rainfall is LOW OR ABSENT, relative humidity is high (90-95%) at night, and days are warm (68 - 80° F.) The fungus grows well only on succulent, new growth. Airborne spores are released on rainless days. Peak spore production occurs by mid afternoon.

Controls

Type Instruction
Biological Bacillus subtilis strain QST or Bacillus pumilis strain QST 2808.
Some compost teas showed efficacy as part of an integrated approach to preventing powdery mildew.
Apply preventative measures in early morning.
Chemical Bicarbonate based products - (Armicarb 100), (Monterey Bi-Carb) or (Kaligreen): when powdery mildew is first observed. A recipe of 1 Tbsp Baking soda + 2 Tbsp light Horticultural oil per gallon of water has shown good results.

Horticultural oils: 3 Tbsp./1 gallon of water and soaps added to oils at 1/4 to 1/2 tsp/gallon of water or alone at 3 Tbsp/gal. have been used as part of an integrated control for powdery mildew . Leaf burning can occur.

Neem.

Sulfur: Do not apply in hot weather (>80º F).
Cultural Plant resistant cultivars. Space plantings for good air circulation. Rake and destroy fallen leaves. Prune out severally infected branches.
Raspberry Crown Borer
Raspberry Crown Borer
Raspberry Crown Borer

Raspberry Crown Borer

(Pennisetia marginata)

Adults are clear winged moths which resemble a yellow jacket: black body with four yellow transverse stripes. Larvae are small and white with a light brown head. Eggs are reddish brown.

Hosts

All rubus species including raspberry.

Lifecycle

ggs are laid on the underside of leaflets in late summer. After hatching the larvae migrate to base of canes to begin their 2nd year below the soil level at the base of the stem. The following spring larvae bore many tunnels and by the middle of the second summer the crown may be extensively damaged. In mid-summer of the second year pupation begins and by late August the clear winged moths appear and mate. After mating the female lays about 140 eggs and a new cycle begins.

Controls

Type Instruction
Cultural Remove alternate hosts (wild rubus species). Prune out and destroy infested canes in the fall. Keep plants properly irrigated and vigorous.
Chemical Insecticides drenched over the crowns in early spring just before bud break may diminish a portion of the larvae. Least-toxic option is pyrethrin.
Red Thread
Red Thread
Red Thread

Red Thread

(Laetisaria fuciformis)

Red thread is especially prevalent during the spring and autumn in slow-growing, nitrogen deficient turf. Circular or irregular patches, red to tan in color, small to larges patches, 2-24 inches.

Hosts

Perennial ryegrass and fine fescue are most susceptible; may also occur on bentgrass, tall fescue and bluegrasses.

Lifecycle

Cool (40-70 degrees), wet conditions (heavy dew, light rain, and fog) are favorable for development. Red thread is most severe during periods when grass is growing slowly as a result of low temperatures, lack of sunlight, drought, inadequate fertility and other diseases.

Controls

Type Instruction
Maintain adequate and balanced fertility. Water as needed early in the day to prevent drought stress. Water should be applied deeply and as infrequently as possible. Selectively prune vegetation to increase air circulation. Moderately resistant cultivars are available.
Redhumped Caterpillar
Redhumped Caterpillar
Redhumped Caterpillar

Redhumped Caterpillar

(Schizura concinna)

Caterpillars with a pronounced reddish hump behind the head.

Hosts

Aspen, Dogwood, Willow, honeylocust, crabapple, apple, and plum.

Lifecycle

Overwinters in a cocoon mixed with leaf litter around the base of the previously infected tree. Moths emerge in late spring, females lay eggs on the underside of the host's leaves in masses of 50-100 eggs. Larvae skeletonize the underside of the leaves. As they mature they move away from the host plant to pupate. There is one generation per year.

Controls

Type Instruction
Control is rarely needed. Cosmetic injury only. If needed products such as Bacillus thurinensis or spinosad would be effective.
Rhizoctonia
Rhizoctonia
Rhizoctonia

Rhizoctonia

(Rhizoctonia spp.)

This fungus causes damping-off-like symptoms on seedlings, root rots, and above-ground stem cankers and fruit rots.

Hosts

Vegetables, flowers, woody species.

Lifecycle

Rhizoctonia persists in soil and in plant debris. It is persistent over very long periods. Cool, moist soils favor this diseases; dry or waterlogged soil discourage it.

Controls

Type Instruction
Biological Treat seed with Bacillus subtilis (Actinovate, Kodiak, RootShield Granules).
Cultural Wait to plant at optimum germination temperatures. Use plastic mulch to prevent fruit contact with soil. Use a 3-year rotation.
Root Maggots
Root Maggots
Root Maggots
Root Maggots

Root Maggots

(Delia spp.)

The maggots are cream to white in color and about 10 mm or 3/8 inch long when mature. The fly is gray and resembles a house fly, but is only 5mm or 3/16 inch long.

Hosts

Cabbage Maggot - Food preferences: Cabbage, broccoli, cauliflower, kohlrabi, radishes, and rutabagas, along with a variety of other plants. Onion Maggot - Food preferences: Onion and related bulb plants. Seed-Corn Maggot - Food preferences: Bean, Field corn, and peas.

Lifecycle

Root maggots spend the winter in a resting stage called a puparium, an elongate brown structure with rounded ends. It is buried from 1 to 5 inches in the soil. In early spring, the adult root maggot, a fly, emerges from the puparium and rises to the soil surface; it lays very small, white, oblong eggs on or just below the soil surface near the base of the host plants. Maggots hatch from the eggs in three to seven days, then migrate through the soil and feed on underground plant parts. The insect causes damage only during the maggot stage, which lasts from three to five weeks. Mature maggots leave the plant and pupate in the soil nearby. In two to four weeks the adult fly emerges. Several generations occur in a growing season.

Controls

Type Instruction
Cultural Use transplants. Older plants may outgrow moderate cabbage maggot populations if well irrigated. Cabbage maggots do not develop at temperatures below 43° F. Plant before or after peak adult maggot flight in the spring (300 degree days at base 43° F. after soils thaw). A floating row cover or cheesecloth tent, which has no gaps through which flies can enter, may be placed over the seed furrow or transplants at planting time. The tent base should extend at least 6 inches on each side of the stems. Standard "backdoor" screening constructed with scrap wood framing has also shown excellent results as a fly barrier in WSU experiments. Washington State University scientists tested other non-chemical techniques on experimental plots. Two popular treatments, use of garlic sprays or wood ashes, had little value.

Do not add uncomposted manure or plant residues, such as fresh grass clippings, to soils. Root maggot adults are attracted to raw organic matter to lay their eggs. There is some indication that well-composted materials may reduce maggot problems. Till under infested plants immediately after harvest.
Biological Numerous parasites and predators attack cabbage maggots, but usually do not reduce populations quickly enough to avoid damage in the short run. Among these parasites are the Rove beetle (Aleochara spp.), an 1/8 inch, black to reddish-brown beetle, and wasps in the Braconidae, Ichneumonidae, also the wasp, Trybiographa rapae. Among the predators are a number of the ground beetles.
Chemical No good options available.
Root-knot Nematodes
Root-knot Nematodes
Root-knot Nematodes

Root-knot Nematodes

(Meloidogyne spp)

Nematodes are microscopic roundworms. They can only move short distances on their own, but may be spread in transported soil or plant debris. They persist over a fairly long time in gelatinous sack-like structures when conditions are unfavorable.

Hosts

Vegetables, flowers, woody shrubs and weeds.

Lifecycle

Females, eggs and juveniles survive in intact roots. Eggs and juveniles are released into the soil when plants decompose. Nematodes are active when soil is moist and warm.

Controls

Type Instruction
Biological Apply parasitic nematodes.
Cultural Control with rotations that include a summer fallow and/or winter cover crop of wheat. Winter grains planted when soil temperatures are below 65° F. help to decrease nematode populations.

In hot weather, heat soil with solarization techniques (clear plastic for 3 - 5 weeks), then uncover and leave to dry.
Rose Curculio
Rose Curculio
Rose Curculio

Rose Curculio

(Merhynchites bicolor)

Common in cooler regions. Adults are 1/4 inch long, black to red beetles with a black snout. They injure buds, preventing them from opening, and riddle flowers that do succeed in opening with holes. Adults may also kill the tips of new shoots.

Hosts

Rose

Lifecycle

Larvae overwinter in the soil near rose bushes. Adult emerges in spring and lays eggs on flower buds. Larvae hatch and feed on flowers.

Controls

Type Instruction
Cultural Pick off adults
Biological Parasitic nematodes may help to control larvae before they emerge in the spring. Fall application is best in Western Montana.
Botanical Neem or pyrethrum can be sprayed on larvae feeding on flowers.
Rose Gall Wasp
Rose Gall Wasp
Rose Gall Wasp

Rose Gall Wasp

(Diplolepsis spp.)

Adults are tiny wasps; larvae are tiny, whitish, and maggot-like.

Hosts

Wild and cultivated roses.

Lifecycle

Immature wasps overwinter in galls on rose stems, leaves, buds and roots. Wasps emerge in the spring.

Controls

Type Instruction
Prune out and destroy galls as they appear in late summer and fall.
Rose Mosaic Virus
Rose Mosaic Virus
Rose Mosaic Virus

Rose Mosaic Virus

()

Rose leaves are distorted, crinkled, with white to yellow discoloration.

Hosts

Rose

Lifecycle

Microscopic virus particles invade phloem and parenchyma tissue. They are obligate parasites and cannot survive outside of their host. Viruses multiply by inducing host cells to form more virus.

Controls

Type Instruction
Cultural Use resistant cultivars. Remove affected branches or plants. Sterilize pruning tools with a 10% bleach solution.
Rose Rust
Rose Rust
Rose Rust

Rose Rust

(Phragmidium mucronatum)

Orange spots are present on leaves. Spots on canes are orange, but become black in the fall and winter.

Hosts

Rose

Lifecycle

In the spring, spores are produced on infected debris and wind blown to healthy plants, where they cause new infections. Symptoms first appear on the undersides of leaves as bright orange, powdery pustules. As these pustules develop, yellow to orange colored spots become visible on the upper leaf surface. Young stems and sepals may also become infected, causing curling and distortion of plant tissue. Eventually, the fungus produces reproductive structures called uredia, which appear on the leaves and canes as reddish-orange pustules.

Controls

Type Instruction
Biological Bacillus pumilis strain (sonata).
Cultural Optimal temperatures for rust infections are 64-70° F and wet leaves for 2-4 hours.

Irrigate early enough in the day so that plant surfaces have time to dry before the cooler temperatures of evening. Keep irrigation off of leaves and branches.

Prune plants for good air circulation. Rake up all dead leaves, prune out old canes in spring before temperatures reach 60-70ºF.
Plant resistant cultivars.
Mineral Sulfur sprays can be effective if sprayed preventatively when rust infection periods occur. Also, Bordeaux mix when buds start to swell.
Rose Stem Girdler/Bronze Cane Borer
Rose Stem Girdler/Bronze Cane Borer
Rose Stem Girdler/Bronze Cane Borer

Rose Stem Girdler/Bronze Cane Borer

(Agrilus aurichalceus)

The adult beetles are about 1/2 inch long, all black with a coppery thorax.

Hosts

Rose, raspberry, currant, gooseberry.

Lifecycle

The larvae overwinters under the bark of canes or in the pith. In spring it pupates within the plant, and the adults lay the eggs near the base of the plant. The larvae tunnel upwards in the plant and pupate inside a chamber the following spring. There is one generation per year.

Controls

Type Instruction
Prune out and destroy infested canes in late winter/early spring.
Sap Beetle
Sap Beetle
Sap Beetle

Sap Beetle

(several species)

Adults are 3/16 inch long, gray/black, oblong beetles; larvae are worm-like.

Hosts

Corn

Lifecycle

Beetles first emerge when early corn cultivars are beginning to tassel and are active over an extended period. Larvae feed within the host plant, then crawl out, fall to the soil where they pupate. The entire cycle may take as little as 3-4 weeks. Two to three generations may occur per year.

Controls

Type Instruction
Mechanical If populations are small, they can be handpicked.
Cultural As damaged or overripe corn are very attractive to sap beetles, the removal of them will result in a reduction of sap beetles.

Tight, long - husked corn varieties are more resistant.
Sapsuckers
Sapsuckers
Sapsuckers

Sapsuckers

(Sphyrapicus varius)

Sapsuckers are woodpeckers 7" to 15" in length. They bore a series of parallel rows of ¼" to 3/8" closely-spaced holes in the bark of limbs or trunks of healthy trees, and use their tongues to remove insects trapped in the sap. These birds usually feed on a few favorite ornamental or fruit trees. Holes may be enlarged thru continued pecking or limb growth, and large patches of bark may be removed or sloughed off. At times, limb and trunk girdling may kill the tree. Wounds of attacked trees may attract insects, porcupines, tree squirrels and leave entrances for diseases and wood-decaying organisms.

Hosts

Trees with thin bark, such as Mountain Ash, Willow and Aspen. Also houses and buildings with wood exteriors near wooded areas/rural settings.

Lifecycle

Some species are migratory, but most live year-round in the same area. Most of the damage occurs from February through June, which corresponds with the breeding season and the period of territory establishment.

Controls

Type Instruction
Cultural Sapsuckers are protected by the Federal Migratory Bird Treaty Act!
Exclusion Place ¾" plastic mesh netting over the area attacked. Be sure to secure the netting so that the birds have no way to get behind it.
Sound Make loud noises using a cap pistol, banging garbage can lid, or commercial noise-producing frightening devices.
Visual Frightening Devices Use stationary model hawks or owls, fake or simulated snakes, owl or cat silhouettes, plastic twirlers, wind chimes, aluminum pans, foil, or scare tapes.
Sawfly
Sawfly
Sawfly

Sawfly

(Macremphytus tarsatus)

The dogwood sawfly is an occasional pest of dogwood. The mature larvae are yellowish with a shiny black head and black spots.

Hosts

Dogwood

Lifecycle

Adult sawflies emerge during late spring and early summer. The female lays eggs on the undersides of the leaves. Upon hatching, the young larvae feed together and skeletonize the leaf. As they grow, they will eat all of the leaf except the midrib. After the second molt, the larvae become covered with a white powdery material. After their final molt they loose the powdery covering and change color. These mature larvae will wander about in search of an overwintering site, generally in soft or decaying wood. There is one generation a year.

Controls

Type Instruction
Control is seldom needed. Hand picking is the easiest way to control this sawfly. Insecticidal soap or Insecticidal soap plus pyrethrum may be applied for control.
Scale
Scale
Scale
Scale

Scale

()

Hosts

Cottony Cushion Scale-Icerya purchasi and actylopius sp. Adult female scale has a fluted cottony egg sac secreted from the body of the scale. Hosts: Woody ornamentals Lecanium Scale - Lecanium corni Crawlers are salmon colored and emerge May through June; there is one generation per year. The scale coverings are dark brown, dome-shaped, and smooth. Hosts: Fruit and deciduous trees and shrubs Oystershell Scale - Lepidosaphes ulmi Pale yellow, tiny crawlers emerge May - June. Hosts: Lilac, poplar, willow, privet, sumac, aspen, green ash & fruit trees Pine Needle Scale - Chionaspis pinifoliae Crawlers are bright orange-red and emerge April - May(about the time common lilac bloom), with one generation per year; scale is white and elongate. Hosts: Conifers, especially mugo pine Scales are grey-brown and shaped like a miniature oyster. There is one generation per year.

Lifecycle

Scales have piercing-sucking mouthparts and suck sap from plants much like an aphid. However, scales are covered with a waxy, protective covering during most of their life cycle which makes their control more difficult than aphids. They are found on branches, needles, and sometimes fruit. Scales usually overwinter in the egg stage beneath the protective scale coverings. Eggs hatch and tiny crawlers emerge in the spring, usually May or June, depending on the weather. They crawl some distance before settling down and starting to feed. They begin to excrete a waxy covering which eventually becomes the protective covering. Treat the CRAWLER STAGE.

Controls

Type Instruction
Cultural Rub scale off plants by hand with a glove or toothbrush. Prune off infestations.
Chemical Time oil or soap sprays to coincide with crawler hatch. Don't put dormant oil sprays on too early. Wait until buds have broken and 1st green tissue is showing. If scale has been a problem, a second oil (or soap) spray may be necessary once leaves are fully expanded. Add pyrethrum to the oil spray. Spray Neem oil at least once. Often, two applications of Neem oil, 7-14 days apart, are more effective. Remember oils and soaps can harm predators and parasites, so only spray if scale is a serious problem. For indoor plants spray insecticidal soap plus pyrethrum 2-3 sprays 7-10 days apart.
Biological Scales have many predators and parasites. Researchers at the University of Illinois report that white clover planted in landscape and Christmas tree plantings enhances the parasitoid wasp (Aphytes chilensi) that attacks pine needle scale (Chionaspis). Ground covers, in general, are important in natural scale control
Septoria Leaf Spot
Septoria Leaf Spot
Septoria Leaf Spot

Septoria Leaf Spot

(Septoria musiva)

On annuals, symptoms first appear as sunken, black flecks. Lesions develop into circular spots with tan centers and dark margins. On woody species spots coalesce to form dead blotches.

Hosts

Vegetables, flowers, woody species such as aspen, cottonwood, poplar, maple, and dogwood.

Lifecycle

Septoria overwinters on dead leaves and in twigs infected the previous season. This disease is favored by wet weather and temperatures of 72 - 79° F.

Controls

Type Instruction
Vegetables Use resistant cultivars. Remove and destroy infected leaves. Use 1 - 2 year rotations. Stake annuals for better air circulation. Keep irrigation water off of leaves. Sulfur applications during warm wet weather may reduce infection.
Woody Plants Rake and destroy infected leaves in the fall. Apply sulfur during warm, wet spring weather.
Shot Hole Disease-Coryneum Blight
Shot Hole Disease-Coryneum Blight
Shot Hole Disease-Coryneum Blight

Shot Hole Disease-Coryneum Blight

(Wilsonomyces carpophilus)

Symptoms appear on new leaves as small reddish spots that enlarge and become purple with a white center. These spots then drop out of the leaf, leaving a "shot hole" appearance. On fruit, dark colored lesions develop and eventually become corky, rough, and scab-like. Infections on maturing fruit are sunken, up to ½ inch long, brown spots, which cause the fruit skin to crack and can be accompanied by a clear, gummy exudate. The fungus can kill dormant buds, blossom buds, and small twigs.

Hosts

Stone fruits (peaches, apricot, plums, sweet cherries).

Lifecycle

The shot hole fungus over winters on dormant infected leaf buds, blossom buds and small twig cankers, but not on old infected leaves. Spores are produced in the early spring; bud and twig lesions may continue to produce spores for two to three years. Wind disseminated spores require free water droplets on the fruit, leaf, or twig surface in order to germinate and cause infection. Temperatures of 70-80° F are optimum for infections which only takes 6 hours of continous moisture; lesions can develop at 45° F if 20 hours of continuous moisture occur. It takes from two to five days for a visible lesion to appear after infection.

Controls

Type Instruction
Cultural Prune out dead branches and twigs. Do not let sprinkler irrigation water wet tree foliage and fruit.
Chemical Protect with a copper spray as buds break in the spring. Spray again at shuck fall with sulfur, captan or daconil, is the "hard" pesticide option if infection periods are severe. If weather is wet and temperatures are >60° F., spray to protect newly expanded leaves.

NOTE: Do not use sulfur on apricots. Bordeaux can be applied in the fall after 50% leaf drop. Captan applied at shuck split.
Shothole Borer
Shothole Borer
Shothole Borer

Shothole Borer

(Scolytus rugulosus)

The adults are small 1/10" gray-black beetles that may begin to emerge in late April or May but can be subsequently be found throughout the growing season.

Hosts

Fruit trees, particularly Prunus species, mountain ash, hawthorn, and occasionally elms.

Lifecycle

The shothole borer spends the winter as a grub-like larva under the bark of trees. They continue to develop the following season, cutting a chamber into the sapwood in spring to pupate. After mating the females seek out branches in poor health, chew out a one to two inch long gallery under the bark. Eggs are laid along the gallery and the newly hatched larvae feed under the bark, making new galleries away from the central egg gallery.

Controls

Type Instruction
Cultural Shothole borers rarely attack healthy actively growing trees. Regularly prune dead or dying branches in which they breed. Destroying branches before adult beetles emerge. Whitewash trunks of young fruit trees to prevent sunburn and reduce potential hazard of attack.
Smut
Smut
Smut

Smut

(Ustilago maydis)

Smut is a fungus which causes swelling in aboveground plant tissues (ie. ears of corn). Plant cells become spongy-gray, then black as the spores mature. Galls can be up to 4 in diameter.

Hosts

Corn (Pasture grasses are susceptible to a similar smut fungus.)

Lifecycle

Smut fungi overwinter in plant debris. Spore formation begins in the spring and is spread by wind and rain. Infection occurs through wounds, especially under high moisture conditions.

Controls

Type Instruction
There is no control for this disease after infection.
REMOVE AND DESTROY all infected plants. DO NOT compost these plants. Soil applications of raw manure favors infection.
Cultural Grow resistant varieties. Rotate crop for 3-4 years.
Snailcase Bagworm
Snailcase Bagworm
Snailcase Bagworm

Snailcase Bagworm

(Apterona helix)

All stages of this insect take place within a coiled, snail-like case that looks like it is made out of dirt. Larvae are greenish or reddish-gray caterpillars with a black head. Adults are wingless and nearly legless moths; they mate while still within the case

Hosts

Willow, mountain mahogany, fruit trees, sage brush, rabbitbrush, and various native and non-native cultivated plants

Lifecycle

Larvae become active in mid-spring and feed on leaves. As the larvae grow and develop they produce a snail-like case out of silk and soil particles. Larvae are mobile and carry the case upright. They mature in late spring to early summer when they migrate to buildings, fence, and/or trees to pupate. Transition to the adult moth takes place in the pupal covering over several weeks. Eggs hatch in mid-summer and the larvae remain in the pupal covering throughout the winter until becoming active in the spring.

Controls

Type Instruction
Control is very difficult since the insect is inside a protective case. Fortunately, this pest does little damage in western Montana.
Mechanical Using a pressure-washer with soapy water will remove bagworms from buildings.
Snow Mold
Snow Mold
Snow Mold

Snow Mold

(Typhula incarnata)

Circular patches of dead, bleached to tan-colored areas up to several feet in diameter.

Hosts

All cool season turfgrasses, especially perennial ryegrass.

Lifecycle

Cold temperatures (32 - 45 degrees F) and prolonged snow cover over wet, unfrozen ground; high levels of soluble nitrogen applied in late fall can increase the likelihood of snow mold. yellow to white circular patches are visible immediately following snow melt. White to grey fungal mycelium may be evident on leaf blades.

Controls

Type Instruction
Avoid applications of nitrogen after October 1st. Improve drainage. Rake and remove tree leaves form lawn before snowfall. In spring, rake affected turf, remove debris, lightly fertilize, and reseed with a soil/seed patch mixture. Mow at recommended height until grass is dormant to prevent excessive top growth and matting.
Sooty Mold
Sooty Mold
Sooty Mold

Sooty Mold

(Various genera and species of fungi)

Sooty molds vary in appearance from thin, dark patches to irregular, blackish masses covering large areas. They may be found on any of the above ground surfaces of host plants such as trunks, leaves, and upper surfaces of branches.

Hosts

All species of trees that are hosts to large populations of aphids, scale, or leafhoppers which produce a sugary substance called honeydew on which sooty mold fungus grows.

Lifecycle

Sooty molds are entirely superficial saprophytes that derive nourishment from insect and plant secretions. They do not injure leaves, but can reduce photosynthesis. Spores of sooty mold fungi are dispersed in water during rain. Thus dark fungal deposits often occur on plant parts and on other surfaces not infested by insects.

Controls

Type Instruction
Wash off with soapy water. Repeat applications are necessary.
Spider Mites
Spider Mites
Spider Mites
Spider Mites

Spider Mites

()

Mites are not insects, although in agricultural contexts they are often discussed with insects for convenience. They are more closely related to spiders than insects. Most insects have three pairs of legs, and three major body parts, whereas mites have two body regions (cephalothorax and abdomen) and can have two, three or four pairs of legs. Many adult insects have wings, but mites never do. Mites are extremely numerous and are found in many kinds of habitats. Their small size makes them difficult to detect, identify, and monitor. The mites that attack fruit trees in the United States fall mainly into two groups: spider mites (Tetranychidae) and rust mites (Eriophyidae).

Hosts

European - Red with large bristles on back; overwinters as egg. Food preferences: Apple, pear, stone fruit. McDaniel - Greenish or yellowish with large spots on sides and smaller spots at rear; overwinters female. Food preferences: Apple, pear. Spruce - Green. Food preferences: Spruce and juniper. Two-spotted - Light green to straw-colored with large black spots on each side; overwinters female Pear, apple, stone fruits, juniper, conifer, ornamentals, house plants, vegetables, small and tree fruits.

Lifecycle

Mites prefer warm temperatures and low humidity. Two-spotted spider mite generations are completed in as little as 10 days at high temperatures (>80° F.). Other spider mites exhibit similar cycles.

Controls

Type Instruction
Cultural Spider mites overwinter on leaves, trash, and weeds on the ground and in plant crevices, so sanitation measures are important.

Providing adequate water for plant growth needs is also important in managing spider mites. Drought and fluctuating wet/dry soil conditions can stress plants in a manner that can cause spider mite populations to increase. Excessive nitrogen fertilization can enhance mite populations.
Biological Several organisms prey on spider mites in field settings; minute pirate bugs and predatory species of mites are among the most important.
Mechanical Overhead watering - and purposeful hosing of plants with water in a garden setting - can dislodge and kill many spider mites.
Chemical Spider mites, especially the two-spotted spider mite, are often very difficult to control with synthetic chemicals. High levels of resistance have developed in many populations.

Dormant oil sprays on deciduous species.

Insecticidal soap: Spray a 2% solution of , if temperatures are less than 85° F. and if the plants are not in direct sun or drought-stressed. Mix 1 T/gal of sulfur with soap sprays for higher populations; spray in the evening, and repeat applications every 5 - 7 days in hot weather.
Spittlebugs
Spittlebugs
Spittlebugs

Spittlebugs

(Clastoptera juniperina)

Nymphs are dark yellow to green and can be found buried in the spittle mass that they produce. Adults are rarely seen, but are 1/4 inch long, oblong-shaped, and light brown with some mottled patterning.

Hosts

Juniper, arborvitae, alder, oak. Other species of spittlebugs feed on shrubs, grasses and herbaceous plants.

Lifecycle

Eggs are inserted in twig tips in early summer; this is where they overwinter. The eggs hatch in late spring and nymphs begin to feed on plants with their piercing/sucking mouthparts. As they feed, they excrete fluid in the form of bubbles that completely enclose the body in the characteristic spittle mass. Development is completed in about 1 month. Adults do not produce spittle masses and are inconspicuous.

Controls

Type Instruction
Wash off with soapy water. Spittlebugs are not a serious concern in the landscape.
Squash Bug
Squash Bug
Squash Bug
Squash Bug

Squash Bug

(Anasa tristus)

Adults are flat and brown, 5/8 inch long. Larvae are bright green, with red heads and legs; they are 3/8 inch long; they leave yellow-green, dusty-looking excrement piles outside holes in the vines. Both adults and larvae stink when crushed. Eggs are bright orange and are laid on the underside of leaves.

Hosts

Cucurbits (cucumber, squash).

Lifecycle

Unmated adults overwinter in protected places near their food source and emerge in early summer. Adults mate and lay eggs about the time squash vines begin to spread. Nymphs hatch and feed on the undersides of leaves. They mature by mid-summer. There is one generation per year.

Controls

Type Instruction
Mechanical If populations are small, they may be handpicked. Boards may also be laid down to serve as traps; the bugs will hide on the undersurface and can be removed along with the boards.

Floating row covers are the most effective control, preventive control. They must be put out as seedlings emerge or immediately after transplanting; secure their edges. Remember to remove row covers when the plants are ready to begin pollination because good pollination will not occur otherwise.
Biological In one study at the University of Kentucky, ground beetles (Carabidae) preyed on squash bugs enough to increase fruit yield by 33%. However, wolf spiders preyed upon minute pirate bugs and nabid bugs (both good predators of squash bugs) and actually increased squash bug density.
Squash Vine Borer
Squash Vine Borer
Squash Vine Borer
Squash Vine Borer

Squash Vine Borer

(Mellitta satyriniformis)

Larvae are white and thick with brown heads; adults are 1 1/2 inch, metallic green/black moths with orange leg hairs and orange marks on their abdomens. They are day fliers.

Hosts

Cucurbits (cucumber, squash).

Lifecycle

Pupae overwinter in the soil in a cocoon. They emerge in early summer as moths. The adults lay eggs on the stems of the host plants. Larvae tunnel into the vine and feed. There is usually only one generation per year.

Controls

Type Instruction
Cultural Grow resistant varieties, when available.
Mechanical Cover vines with floating row cover early in the growing season; uncover later for pollination to occur.

Locate the point of injury, split the vine, and puncture the larva. Cover the cut stem with moist dirt to encourage roots to volunteer.

Dispose of the affected plants after harvest.
Tarnished Plant Bug
Tarnished Plant Bug
Tarnished Plant Bug
Tarnished Plant Bug

Tarnished Plant Bug

(Lygus lineolaris)

Adults are oval, brown, 1/4 inch long bugs with a white triangle on their back; nymphs are smaller, yellow-green and have black spots on their backs.

Hosts

Potatoes, celery, lettuce, beans, peas, fruits.

Lifecycle

Adults overwinter under bark or leaf littler, emerge in early spring to lay eggs in leaf tissue; eggs hatch in 10 days. Tarnished plant bugs feed on developing leaves, fruits, and flowers, killing the areas around feeding sites. This can cause abortion of young flowers, developing seeds, or fruit. Catface injuries to fruit are some of the more commonly observed distortions caused by tarnished plant bug feeding.

Controls

Type Instruction
Cultural Till after harvest. Attrack native predators (bigeyed bugs, damsel bugs, pirate bugs) with groundcovers and pollen plants.
Botanical Neem or pyrethrin, sprayed in the evening with a soap spreader-sticker (1 oz/gal water), will control higher infestations.
Mechanical White sticky traps may be used to control low infestations
Tussock moth
Tussock moth
Tussock moth
Tussock moth

Tussock moth

(Orgyia pseudotsugata)

First instars are gray with long hairs. Later instars develop four dense tussocks of yellow brown hairs on their backs. Mature larvae are up to 1 1/4 inches long, have two long dark tufts of hair just back of the head, a longer tuft on the posterior end, four tussocks on their back and the rest of the body is covered with short hairs radiating from red, button-like centers. Adult male moths have rusty colored forewings and gray-brown hind wings, with a wing span of about 1 inch. The adult females are wingless and thick bodied.

Hosts

Douglas-fir, all true firs, spruce, pine and larch. Also cottonwood.

Lifecycle

Eggs overwinter in a mass covered with the gray hairs of the female. Eggs hatch in late spring and caterpillars migrate to the new growth at the top of the tree. Some are dispersed by the wind to new hosts. Caterpillars first feed solely on new growth, then as the larvae mature they move on to the older needles. Entire trees may be defoliated if the populations are high. By late summer caterpillars are full grown and may migrate away from the infested tree. They pupate in brownish spindle-shaped cocoons. Adults emerge in mid to late summer.

Controls

Type Instruction
Spiders, parasitic wasps, and tachnid flies provide some natural control. Extreme winters and freezing spring temperatures limit populations. Bt(Bacillus Thuringensis) can be used if larvae are newly hatched and still small. Add insecticidal soap to Bt sprays. Pyrethrum plus insecticidal soap if populations are high.
Ugly Nest Caterpillars
Ugly Nest Caterpillars
Ugly Nest Caterpillars
Ugly Nest Caterpillars

Ugly Nest Caterpillars

(Archips cerasivorana Fitch)

Caterpillars are olive green, reaching 3/4 inch long when mature and found clustered in groups.

Hosts

Most common on chokecherry, but may be found on other deciduous trees and shrubs.

Lifecycle

The ugly nest caterpillar overwinters in the egg stage on twigs. Eggs hatch in late spring and the larvae spin a dense web around feeding sites that become filled with their excrement and bits of leaves. Caterpillars become full grown in 4-6 weeks and pupate around the nest. Adult moths appear from July through September and overwintering eggs are laid in late summer or early fall. There is one generation per year.

Controls

Type Instruction
Natural predators keep this pest at low populations. Bt (Bacillus thuringensis) is effective on younger larvae.
Venturia Shoot Blight
Venturia Shoot Blight
Venturia Shoot Blight

Venturia Shoot Blight

(Venturia populina)

Infected leaves develop irregular brown to black areas and become distorted and curled. Leaf stems may become constricted at the base. The fungus spreads down through the shoot which blackens and curls to resemble a shepherd's crook.

Hosts

Aspen, cottonwoods, and poplars.

Lifecycle

Spores of this fungus overwinter in fallen leaves as well as previously diseased stems and twigs. Spores are wind-blown early in the season and infect newly expanding leaves and shoots. During extended wet periods, secondary infection may result when fungus spores are rain splashed to other parts of the tree growth. Infection is most rapid at 60 - 77° F. when leaves are wet.

Controls

Type Instruction
Avoid nitrogen fertilization- succulent growth is most susceptible. Keep irrigation water off of trunk, branches, and leaves. Prune infected shoots out on a hot, dry day. Rake and destroy fallen leaves during the growing season to reduce secondary infection. Protect new growth with sulfur during wet weather and temperatures <60° F.
Verticillium Wilt
Verticillium Wilt
Verticillium Wilt
Verticillium Wilt

Verticillium Wilt

(Verticillium species)

Foliar symptoms typically include wilting, curling, yellowing, marginal or interveinal browning and death. Often these symptoms may look like water stress and can occur on only one side of the plant. On woody plants, symptoms may include dieback of branches or a portion of the plant. Also, wood under the bark may exhibit discolored streaks or bands. The color of the streaks can range from light tan to grayish olive to brownish-black. Yellowing and defoliation often progress from the bottom to the top of the plants.

Hosts

Ash, elm, sumac, linden, maple, raspberry and occasionally fruit trees; vegetable crops, especially solanaceous crops (eggplant, pepper, potato, tomato).

Lifecycle

Verticillium wilt is caused by a soil inhabiting fungus which affects the plant's vascular system. Infection occurs through the roots or where damage to the stem has occurred near the soil line. Once the fungus invades the plant, it spreads into the water-conducting tissues (xylem) disrupting water movement and normal plant functions. The pathogen survives in plant debris, in roots and trunks of killed trees for several years and as a resting structure (microsclerotia) can persist in the soil for years. Water-stressed or wounded trees are most susceptible. Wet, warm (65-72° F.) weather encourages this fungus.

Controls

Type Instruction
Cultural There is no cure for Verticillium. Use resistant cultivars or species. Conifers, birch, and dogwood are not susceptible. Keep woody species well-watered. High nitrogen fertilizers can increase wilt severity. Remove and destroy infected plants. Prune and destroy affected tree branches before leaves fall.

In the case of vegetable crops, do not plant out transplants until soil temperatures are 65-70° F. Rotate your crops on a 4 - 5 year basis with non-susceptible plants such as sweet corn, spinach, beans, and peas. DESTROY infected plants Soil solarization for 4 - 6 weeks in July and August may help.

For woody plants: Mulch with 1 - 3" of low pH compost.
Preventative For vegetables, soak seeds in hot water or a 0.5% bleach solution before planting.
Western Cherry Fruit Fly
Western Cherry Fruit Fly
Western Cherry Fruit Fly
Western Cherry Fruit Fly

Western Cherry Fruit Fly

(Rhagoletis pomonella Walsh)

Cherry fruitfly maggot larvae are legless, 1/4 to 3/8 inch long larvae, creamy white in color except for 2 dark mouth hooks. Adults are housefly sized with darker patterned "W" or "Z" markings on clear wings.

Hosts

Cherries and plums.

Lifecycle

Flies overwinter as pupa in the soil. Adults emerge and move to cherry trees in late May through June depending on weather. They begin to lay eggs in developing fruit immediately. Eggs hatch and maggots feed near the cherry pit.

Controls

Type Instruction
Cultural Avoid water extremes and heavy nitrogen fertilization.
Biological Birds prey on adult flies. Don't put netting on trees (to keep fruit-eating birds out) until cherries start to ripen.
Botanical If you catch 2 or more flies per week on traps, spray pyrethrin or Spinosad every 7-10 days thru harvest.
Traps Trap adult flies with yellow sticky card or red ball sticky traps. Put traps out in late May.
Western Flower Thrips
Western Flower Thrips
Western Flower Thrips
Western Flower Thrips

Western Flower Thrips

(Frankliniella occidentalis Pergande)

Adults are tiny (1/8 inch), winged and pale yellow-brown in color. Nymphs are whitish, 1/8 inch and resemble elongated aphids. The distinguishing signs of thrips are tiny black dots (frass) associated with leaf damage. Leaves have white flecks that look like the chlorophyll has been sucked out.

Hosts

Many kinds of flowers and vegetable crops.

Lifecycle

It is unclear whether WFT are able to overwinter outdoors in Montana. Researchers in Southern Ontario report that WFT do not overwinter outdoors there. However WFT reportedly overwinters outdoors in Pennsylvania. Thrips pupate in growing media, leaf litter, and/or flowers. Adults emerge and lay eggs in leaves or flowers. Optimum temperatures are 80 - 85° F. At these temperatures, development from egg to adult can take 1-2 weeks (generally it is 2-3 weeks). Larva feed on leaves and flowers. WFT has large reproductive power; adult females can lay between 150 - 300 eggs during their 30 - 45 day life. WFT have been implicated in the mechanical transmission of fungal pathogens (Fusarium and Botrytis) and virus in greenhouse crops. Greenhouse sanitation with a summer fallow period of 4 - 5 days at 105° F. and 10% relative humidity is recommended to kill all stages of WFT.

Controls

Type Instruction
Mechanical Use yellow or blue sticky traps to monitor thrips populations.
Biological In indoor, greenhouse, or very high humidity outdoor situations, Beauveria bassiana (BotaniGard and Naturalis-O) can be used. Beauveria is usually ineffective at relative humidities below 50% and efficacy increases with increasing humidity. In one greenhouse test, Beauveria (esp. the oil formulation) killed up to 82% of thrips on rose foliage at 79° F. and 75% relative humidity. Beauveria works more slowly than insecticides so should not be relied on if thrip populations are already high. Good foliage coverage is essential. In a California study on roses, thrips were controlled with weekly Beauveria applications.

In greenhouse studies, flower thrips at low population levels were controlled by release of a phytoseiid mite, Neoseiulus cucumeris. This predaceous mite works best at 54-86° F. and 70-80% humidity. Good establishment can take one month, so mite release is required prior to thrips establishment.
Botanical Spinosad insecticide performed best against western flower thrips in a study on Chrysanthemum.
Pyrethrin and neem can also be used for thrips on many plants.
Western Gall Rust
Western Gall Rust
Western Gall Rust

Western Gall Rust

(Endocronartium harknessii)

Rough, globular galls on trunks or branches of pines. When the fungus is fruiting the galls are yellow or orange. Galls rupture to release yellow-orange spores on current year's shoots.

Hosts

Lodgepole, mugo, Scots, Austrian and ponderosa pine.

Lifecycle

Rust infection is favored by prolonged periods of wet, cooler(60-65ºF) weather in spring (May/June) when galls rupture and produce yellow-orange powdery spores.

Controls

Type Instruction
Cultural Keep irrigation off of needles, branches, and trunk. Maintain plants for good air circulation. Prune to maintain good air circulation. Prune out galls or remove heavily infected trees.
Mineral Sulfur sprays can be effective if sprayed preventatively when rust infection periods occur when yellow-orange galls are visible in wet weather.
Western Raspberry Fruitworm
Western Raspberry Fruitworm
Western Raspberry Fruitworm
Western Raspberry Fruitworm

Western Raspberry Fruitworm

(Byturus Bakeri)

Adults are small brown oblong beetles ¼ to ½ inch long. The adults cause characteristic slits in the leaves from their feeding and destroy developing buds. The larvae feed within the blossoms and inside developing fruit.

Hosts

Raspberries, blackberries, and other cane fruit.

Lifecycle

Fruitworms overwinter as pupa and adult beetles emerge from the soil in the spring. They feed on the leaves and lay their eggs near the fruit buds.

Controls

Type Instruction
Pre-bloom sprays of spinosad or pyrethrum can be applied as flower buds appear and again before flowers are open to limit populations of adults. Since fruitworms fall to the ground in mid-summer, fall fruiting cultivars usually do not have a problem with this insect. Late summer tillage and early spring tillage may destroy pupa in the soil.
Western Spruce Budworm
Western Spruce Budworm
Western Spruce Budworm
Western Spruce Budworm

Western Spruce Budworm

(Choristoneura Occidentalis Freeman)

The larvae have olive brown to reddish brown bodies with brownish heads. They have prominent, ivory-colored, paired spots on each body segment. They range in size from 1 to 1-1/2 inches long at maturity. The adults are highly variable in color from mottled med-dark brown to orange forewings and tan hind wings, their wingspan is about 1 inch.

Hosts

Spruce, fir , Douglas-fir.

Lifecycle

There is one generation of budworm per year. Adult females lay a shingle-like mass on the underside of needles. Eggs hatch in early autumn and the newly-hatched larvae migrate to overwintering sites in silken shelters under bark scales or among lichen. Larvae emerge in late spring to mine buds, developing cones and old needles. As new needles emerge they are webbed together in protective nests where the larvae feed until they are mature in about 30 - 40 days. Pupae are formed in the silken nests and adults emerge in late summer to mate and lay eggs.

Controls

Type Instruction
Biological Birds are important predators.
Spray Bacillus thuringiensis (Bt-kurstaki) plus 1 - 2 Tbsp. insecticidal soap per gallon of water at first swelling of spring buds. Repeat applications necessary.
Botanical Spinosad or neem(Bioneem, Azatin, Neemix, or Nemagad) plus insecticidal soap when buds swell on spruce trees.
White Grubs
White Grubs
White Grubs

White Grubs

(Scarabaeidae)

White grub is the common name applied to larvae of beetles in the family Scarabaeidae. Grubs are white, C-shaped, wormlike larva with dark heads and prominent front legs. June Beetle grubs are the most common white grubs in Missoula.

Hosts

Turf grass.

Lifecycle

Life Cycle: Eggs are usually laid on or near the food source in the soil or on a turf plant, depending on the species. After hatching the larvae develop through a series of growth stages known as instars (usually 3 to 5) before pupating into adults. Grubs feed primarily on roots from spring through late summer.

Controls

Type Instruction
Biological Parasitic nematodes and Milky Spore disease (Bacillus popilliae) are least-toxic options. After application, irrigate with 1/2" - 1" of water.
Cultural Tall fescue lawns appear to be resistant to white grubs.
Chemical Mow and remove clippings prior to applying chemicals. Imidacloprid and trichlorfon in granular or liquid form. Apply water to treated area immediately after application .5 to 1". Do not let pets or children on treated areas until watered in and completely dry.
White Pine Blister Rust
White Pine Blister Rust
White Pine Blister Rust

White Pine Blister Rust

(Cronartium Ribicola)

Rough elongated cankers develop on trunks. Orange spore masses burst through cankered bark in early spring. Pitch flows around the canker wound.

Hosts

The fungus attacks all five needle pines.(limber, bristlecone, whitebark)

Lifecycle

The fungus develops annually on the stems and leaves of the alternate host plants (currants and gooseberries), infecting pine needles in late summer and late fall where it lives perennially in the inner bark of the pine host.

Controls

Type Instruction
High humidity and temperatures of 60-75° F for 20 or more hours cause rust infection.

Prune out and destroy infected branches

Eliminate the alternate host (currants and gooseberries).
White Pine Weevil
White Pine Weevil
White Pine Weevil
White Pine Weevil

White Pine Weevil

(Pissodes strobi)

The insect overwinters in the adult stage under leaf litter and in other protected areas. In late spring to early summer, weevils become active and seek out spruce trees. They feed on the cambium of main branches near the leader and insert eggs into the feeding cavities that are formed. Eggs hatch in 1 - 2 weeks and the grubs tunnel downward underneath the bark. Damage increases as the larva grow. Wilting of terminal branches becomes noticeable by mid-summer. By late summer, the top of spruce trees display a characteristic dead "shepherd's crook". When full grown, the larva tunnel deeper into the stem and form a cocoon made of wood chips in which they pupate. In about 2 weeks, adult beetles emerge leaving small holes in the bark. Adult weevils feed on the needles, buds, and twigs of spruce for several weeks before going into a dormant condition for overwintering.

Hosts

Colorado blue spruce, Englemann spruce.

Lifecycle

The adult stage of the white pine weevil is a small (1/4 inch) snout beetle flecked with brown and white patches. Larvae look like a grain of cooked white rice with a brown head.

Controls

Type Instruction
Cultural As soon as the ground begins to thaw in early spring, rake up the needles from beneath spruce trees to disturb overwintering weevils. Leave the soil exposed until spruce buds begin to break, then mulch with 1 - 3 inches of composted wood bark chips (such as Soil Pep). Remove and destroy wilted terminal branches as soon as you notice them.
Botanical Spray only the tops of trees thoroughly with pyrethrin when spruce buds break and begin to grow or "candle" in the spring and again when new growth is 1-2" long.
Chemical Spray only the tops of trees thoroughly with cyfluthrin or permethrin when spruce buds break and begin to grow or "candle" in the spring and again when new growth is 1-2" long.
A soil drench of imidacloprid in late fall.
Wireworm
Wireworm
Wireworm
Wireworm

Wireworm

(Elateridae family)

Young are brown to yellowish worms; have a shiny, hard skin; are cylindrical and 1/3 to 1/2 inch long. Adults are click beetles, black to grayish or brown with dark spots on the head and bands across the wing cover; 1/2 inch long. Eggs are laid in damp soil several inches beneath the surface.

Hosts

Bean, beet, carrot, corn, lettuce, onion, pea, potato.

Lifecycle

One generation per year; the life cycle requires one to six years to complete, depending on species. Eggs are laid underground in early spring or summer and pupation takes place in late summer. Larvae feed entirely underground, chewing on germinating seeds or on the roots, stems, and tubers of many plants. Adult beetles overwinter in cells in the soil or in rotten wood and plant debris.

Controls

Type Instruction
Cultural Grow resistant crops. Cultivate the garden frequently enough to expose the worms to predators and to discourage egg laying. Practice good sanitation - remove rotten wood and plant debris from area; compost at a distance from the growing area. Do not plant into a previously-sodded area until the second season after tilling in the grass. Red and sweet clover and small grains also support populations of wireworms.
Biological Use parasitic nematodes.
Mechanical Wireworms may be trapped in pieces of potato buried an inch below the soil surface. Dispose of the pieces later and replace with new ones.
Botanical Ecotrol G is a granular form of botanical oils(cinnamon, clove, thyme). It is to be applied as a band or with seeds at or after planting at depths of 4-8".
2,4-D
2,4-D

2,4-D

Symptoms
Cupped leaves; twisted and distorted new growth.

Treatment
Leach through with irrigation.

Dicamba

Dicamba

Symptoms
Distorted, usually upward cupping leaves.

Treatment
Leach through with irrigation.

Glyphosate (Roundup)

Glyphosate (Roundup)

Symptoms
Slight yellowing to stunted distorted and narrowed leaves; witches broom at buds.

Treatment
Leach through with irrigation.

Milestone
Milestone

Milestone

Symptoms
Puckered, distorted leaves.

Treatment
Leach through with irrigation. May be persistant in soil for years.

Salt
Salt

Salt

Symptoms
Yellowing, then browning of leaf margins; red tip burn on conifer needles.

Treatment
Leach through with irrigation.

Leaf Scorch
Leaf Scorch

Leaf Scorch

Symptoms
Leaf margins and the area between leaf veins yellows or darkens. As the condition progresses, entire leaves may dry up, turn brown and become brittle. Leaves sometimes wilt rapidly and may remain a pale green color, even though dried out. Damage is usually more pronounced on the upper, windward, or southern side of trees. Plants may lose many leaves prematurely during late summer and exhibit twig dieback.

Treatment
Maintain vigor through proper watering especially in July and August. Deep water the entire area under the canopy, one and one-half to three times farther than the branches. Sufficient moisture will help keep the trees vigorous enough to withstand pest attacks, as well as help prevent winter injury. Avoid frequent, light waterings, and watering only at the base of the tree trunk. Mechanical Treatment: Avoid over-fertilization. In many parts of Montana, additional tree fertilizers are not needed, especially when planted in turf areas that receive fertilizers. Unless trees are showing symptoms of nutrient deficiency, such as chlorosis, stunted growth, or deformed foliage, refrain from fertilizing them unless soil tests indicate otherwise.

Boron
Boron

Boron

Symptoms
Buds die, seedlings stunted, leaves cupped with brown margins; fruits are cracked with internal dark spots, fruit tree branches have brown, dead, cracked areas on bark

Treatment
Be careful when adding boron; only small amounts needed and it can easily be over applied

Calcium
Calcium

Calcium

Symptoms
Younger leaves pale; terminal buds die; sunken, darkened tissue on fruits of tomato and apple.

Treatment
Add gypsum or Calcium nitrate

Iron
Iron

Iron

Symptoms
Yellowing between veins of youngest leaves; entire crown of new leaves turns pale, whitish-yellow.

Treatment
Iron deficiencies are common on high pH soils or poorly drained. Lower pH with sulfur. Add iron in a chelate form.

Magnesium
Magnesium

Magnesium

Symptoms
Middle or lower leaves yellow in between leaf veins; veins appear green; interveinal browning plus spots, cupped leaves; reduced growth

Treatment
Uncommon in Montana but can be added in the form of dolomitic lime unless pH is high. Spraying with Epsom salts (magnesium sulphate) is effective.

Nitrogen
Nitrogen

Nitrogen

Symptoms
Older leaves paler and small; general yellowing. Small imperfectly formed roots. Reduced growth.

Treatment
Add liquid nitrogen for fast response, afalfa meal, blood meal are good to incorporate in soils.

Phosphorous
Phosphorous

Phosphorous

Symptoms
Leaves on young plants are purple. Depressed fruit and seed formation; delayed ripening, poor quality fruits, reduced flowering.

Treatment
Deficiency is common in cold soils warm soils before planting with plastic.

Potassium
Potassium

Potassium

Symptoms
Yellowing/browning on margins of lower leaves, plants will wilt easily; fruits are small and do not store well with blotching internal color.

Treatment
Improve soil structure, add organic matter. Plant based seaweed meal and manures are a good source of potassium.

Sulfur
Sulfur

Sulfur

Symptoms
General yellowing of younger leaves first, then entire plant; uncommon plus hard to distinguish from nitrogen deficiency.

Treatment
Adding manure should provide enough available sulfur to be adequate in most soils.