Pests



Alternaria Leaf Blight

 

 

 

Plant Diagnostic Database

Alternaria Leaf Blight  (Early Blight on Tomato)

Alternaria spp. (Alternaria solani on Tomato)                         

Alternaria on cantaloupe

alternaria on sunflower

Alternaria on potato

Alternaria on potato stem

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Cucurbits (cucumbersquash), Solanaceous crops (eggplantpepperpotatotomato) and other vegetables such as peas, onion and cabbage.
Description:
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.
Life Cycle:                                        
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:
Cultural:
Chemical:
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.              

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.

 

 

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Angular Leaf Spot

 

 

 

Plant Diagnostic Database

Angular Leaf Spot  (Pseudomonas syringae pv. lachrymans)

                       

angular leafspot_cucumber

angular leafspot_cucumber2

angular leafspot_cucumber3

angular leafspot_cucumber4

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Cucurbits (cucumbersquash), a similar strain infects beans.
Description:
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.
Life Cycle:
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:
Cultural:
Chemical:
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. 
      

Copper can be sprayed to protect leaves when weather is wet and warm.  

 

 

***This bacteria is associated with ice nucleation, a primary factor in frost injury to plants.  Check out this award winning short film by an MSU student about the formation of snow.

Anthracnose

 

 

 

Plant Diagnostic Database

Anthracnose  (multiple species)

                       

anthracnose sycamore

anthracnose sycamore_leaf

anthracnose cucumber

anthracnose cucumber_fruit

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Woody Plants:  Ashmaplerosesycamore, and  many other deciduous trees and shrubs. 

Vegetables: Members of the Cucurbitaceae family (cucumber,squash), raspberry.

Description:
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. 
Life Cycle:
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:
Cultural:
Chemical:

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.

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

 

 

 

Plant Diagnostic Database

Aphids  (multiple species)

                       

Aphidonash

Aphidonleaf

Aphidsonleaf

Aphidpetiolegall

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Type: Hosts: Description:
Apple Applehawthorn,mountain ash,crabapple. Yellow-green
Bean Beansbeets,cucumbercarrots,lettuce, etc. Black
Black Cherry Cherriesplums, wild mustards. Large, shiny black
Black Willow Willow Large, shiny black
Box Elder/Maple Acer species Green
Elm Leaf Elm Pale yellow, whitish fluff
Giant Conifer Pinessprucesfirs,juniper. Reddish-brown
Green Peach Fruit trees, vegetables, and flowers Green
Leaf-curl Ash Ash Yellow-green, whitish fluff
Leaf-curl Plum Plum Shiny yellow-green
Petiole-Gall Poplars, cottonwoods Pale green
Potato Rose, nightshade family includingpotatoes / tomatoes/eggplant, vegetables, flowers, weeds. Pink and green
Description:
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.    
Life Cycle:
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:
Cultural:
Monitoring:

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.

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:

Mechanical:

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.

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:

Botanical:

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.

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.

 

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Aphids (2)

 

 

 

Plant Diagnostic Database

Aphids  (multiple species)

                       

anthracnose sycamore

anthracnose sycamore_leaf

anthracnose cucumber

anthracnose cucumber_fruit

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Type: Hosts: Description:
Apple Applehawthorn,mountain ash,crabapple. Yellow-green
Bean Beansbeets,cucumbercarrots,lettuce, etc. Black
Black Cherry Cherriesplums, wild mustards. Large, shiny black
Black Willow Willow Large, shiny black
Box Elder/Maple Acer species Green
Elm Leaf Elm Pale yellow, whitish fluff
Giant Conifer Pinessprucesfirs,juniper. Reddish-brown
Green Peach Fruit trees, vegetables, and flowers Green
Leaf-curl Ash Ash Yellow-green, whitish fluff
Leaf-curl Plum Plum Shiny yellow-green
Petiole-Gall Poplars, cottonwoods Pale green
Potato Rose, nightshade family includingpotatoes / tomatoes/eggplant, vegetables, flowers, weeds. Pink and green
Description:
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.    
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:
Cultural:
Monitoring:

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.

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:

Mechanical:

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.

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:

Botanical:

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.

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.

 

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Apple and Thorn Skeletonizer

 

 

 

Plant Diagnostic Database

Apple and Thorn Skeletonizer (Gymnosporangium juniperi-virginianae)

                       

appleandthorndamage2thumb

appleandthorndamage3thumb

appleandthornlarva

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
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:
Biological: Botanical:

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.

Bacillus thuringiensis (Bt-K). Treat newly hatched larvae, before leaves curl. This works best when temperatures are warm (>50ºF). 

Chemical:

 

Spinosad - Treat by spraying newly hatched larvae.

Azadirachtin (neem extract)

 

 

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Apple Scab

 

 

 

Plant Diagnostic Database

Apple Scab (Venturia inaequalis)                       

Applescabfruit

applescabfruit1

Applescableaf

applescableaves

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
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:
Cultural: Biological:  Chemical:

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

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.

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.  

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Armillaria Root Disease

 

 

 

Plant Diagnostic Database

Armillaria Root Disease (Armillaria spp.)

                       

Armillariarotmushrooms

armillariarootrottrunk

Armillariatrunk

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Remove diseased tree stumps, roots and all.  Plant resistant species such as Western Larch.

 

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Army Cutworm

 

 

 

Plant Diagnostic Database

Army Cutworm (Euxoa auxiliaris)

                       

armycutwormadult

Armycutwormlarva

armycutwormlarva1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Biological: Traps:
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.

Blacklight traps catch male and female moths; pheromone traps catch only the males. Both traps are most effective as indicators of population levels.

Chemical: Mechanical:
Spray Spinosad in the evening 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.)

 

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Ash Plant Bug

 

 

 

Plant Diagnostic Database

Ash Plant Bug (Tropidosteptes amoenus)                   

Ashplantbug

Ashplantbugcloseup

Ashplantbugdamage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Ash.

Description:
Light brown true bug about ¼ to ½ inch long . Nymphs are oval, shiny yellowish or reddish brown and lack wings.
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:
Chemical:
Use insecticidal soap if >40% of leaves are infested. Injury is mostly cosmetic only.

 

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Ash Yellows

 

 

 

Plant Diagnostic Database

Ash Yellows (Phytoplasma)           

Ashyellows

Ashyellows2

Ashyellows1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Ash

Description:
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.
Life Cycle:
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:
Remove infected trees if badly infected.

 

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Asparagus Beetles

 

 

 

Plant Diagnostic Database

Asparagus Beetles (Crioceris asparagi)

                       

Asparagusbeeltelarva

Asparagusbeetle

asparagusbeetledamage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Asparagus and related crops.

Description:
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.
Life Cycle:
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:
Cultural: Mechanical:
Mow down the foliage in late winter or early spring to get rid of overwintering areas. Pick asparagus regularly.

The larvae feed on asparagus berries; shake off the berries onto a sheet and destroy them. 

Botanical:

Chemical:

Pyrethrum can be sprayed on larva. Spinosad sprayed on larva.

 

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Aster Yellows

 

 

 

Plant Diagnostic Database

Aster Yellows (Phytoplasma)

                       

Asteryellowscarrot

Asteryellowscarrots

asteryellowsgillardia

asteryellowslettuce

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

VegetablesCarrots, celery, lettuce, parsnips .

Flowers:  Asters, Echinacea, and annual flowers such as zinnia.

Description:
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.
Life Cycle:
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:
Cultural:
Control the leafhopper with pyrethrum plus insecticidal soap. Plant resistant cultivars when possible. At the Frontier Herb Company Experimental Farm in Iowa, planting crops in polycultures (beds comprised of several crop species) has greatly reduced the incidence of aster yellows.  Row covers can be used to cover crops when seedlings emerge.

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Bacterial Brown Spot

 

 

 

Plant Diagnostic Database

Bacterial Brown Spot  (Pseudomonas syringae pv. syringae)

(Bacterial Blight/Canker)                       

bacterial brwonspot_bean

Bacterial blight on bean

bacterial brwonspot_peach

bacterial brwonspot_peach2

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Lilac, cotoneaster, ornamental and fruiting cherriesplums, and privet. Vegetable crops(e.g.-broccoli, pea) are susceptible to various subspecies of P. syringae.
Description:
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.
Life Cycle:
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:
Cultural:
Chemical:
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.

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. 

 

 

***This bacteria is associated with ice nucleation, a primary factor in frost injury to plants.  Check out this award winning short film by an MSU student about the formation of snow.

Bacterial Spot

 

 

 

Plant Diagnostic Database

Bacterial Spot (Xanthomonas campestris)

                       

bacterialspotofpepper

bacterialspottomato1

bacterialspottomatoleaf

bacterialspottomato

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Tomatoes and peppers.

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

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Bacterial Wetwood

 

 

 

Plant Diagnostic Database

Bacterial Wetwood or Slim Flux

   ( Enterobacta, Klebsiella, and Pseudomonas bacteria and various yeasts)           

bacterialwetwood

bacterialwetwood2

bacterialwetwood1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
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.

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Bacterial Wilt

 

 

 

Plant Diagnostic Database

Bacterial Wilt (Erwinia tracheiphila)

                       

bacterialwilt

bacterialwiltbeetle

bacterialwiltplant

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Cucurbits (cucumber, squash).

Description:
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.
Life Cycle:
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:
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!
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.

 

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Beet Armyworm

 

 

 

Plant Diagnostic Database

Beet Armyworm (Spodoptera exigua)

                       

beetarmyworm

beetarmywormhatch

beetarmywormadult

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Biological: Botanical:
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.

Bacillus thuringiensis (Bt-K). Treat newly hatched larvae. This works best when temperatures are warm (>50ºF). 

Chemical:
Spinosad - Treat by spraying newly hatched larvae.

 

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Black Knot

 

 

 

Plant Diagnostic Database

Black Knot ( Dibotryon morbosum formerly Apiosporina morbosa)

                       

Blackknotsign

blackknottwig

blackknotsymptom

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
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.

 

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Black Leg

 

 

 

Plant Diagnostic Database

Blackleg (Erwinia caratova)

                       

blacklegpotatotuber

blacklegfoliage

blacklegplant

Blacklegpotato

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

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

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Black Rot

 

 

 

Plant Diagnostic Database

Black Rot (Xanthomonas campestris)

                       

blackrotbroccoli

blackrotcabbagehead

blackrotcauliflower

blackrotcabbage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural:
Chemical: Mechanical:

Use 2-3 year rotations and destroy infected plants. Grow resistant varieties.

Spray copper if weather is wet.

Treat seed with hot (120° F.) water 30 minutes before planting.

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Black Spot

 

 

 

Plant Diagnostic Database

Black Spot (Diplocarpon rosae)

                       

Blackspot

blackspotrose

blackspotrs

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Rose

Description:
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.
Life Cycle:
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:
Cultural: Chemical:
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

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.  

 

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Black Vine Weevil

 

 

 

Plant Diagnostic Database

Black Vine Weevil  (Otiorhynchus sulcatus)

                       

blackvineweevil

blackvineweeviladult

blackvineweevildamage

blackvineweevillarva

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Strawberries, clematis, euonymus, lilac, rhododendron.

Description:
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.
Life Cycle:
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:
Biological:
Chemical:

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.

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.

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Black Witches Broom

 

 

 

Plant Diagnostic Database

Black witches broom (Apiosporina collinsii)

                       

blackwitchesbroomonserviceberry

blackwitchesbroom

blackwitches broom1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Various species of serviceberry (Amelanchier).

Description:
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.  
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:
Prune out infected branches and keep irrigation off of plants.

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Boxelder Bugs

 

 

 

Plant Diagnostic Database

Boxelder Bugs (Leptocoris trivittata)

                       

Boxelderbug

boxelderbug1

boxelderbugbaby

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Boxelder, ash, and maple.

Description:
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.
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:
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 

 

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Bronze Birch Borer

 

 

 

Plant Diagnostic Database

Bronze Birch Borer (Agrilus anxius)

                       

bronzebirchborer

bronzebirchborerdamage

bronzebirchborergalleries

bronzebirchborer1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Birch.

Description:
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.
Life Cycle:
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:
Cultural:
Chemical:

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.

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.

 

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Brown Felt Blight

 

 

 

Plant Diagnostic Database

Brown Felt Blight (Herpotrichia juniperi:  Firs and Spruces, Neopeckia coulteri:  Pines)

                       

brownfeltblight

brownfeltblight fir

brownfeltblightpine

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

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

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:
REMOVE AND DESTROY infected branches.

 

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Brownheaded Ash Sawfly

 

 

 

Plant Diagnostic Database

Brownheaded Ash Sawfly (Tomostethus multicintus)

                       

brownheadedashsawflylarva

brownheadedashsawfly

brownheadedashsawflydamage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Ash

Description:
The larvae are pale green and worm-like with dark heads. Adults are small, black wasps.
Life Cycle:
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:
Chemical:
Spray with insecticidal soap, spinosad, or neem extract if >40% of leaves are infested with larvae.

 

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Cabbage Loopers

 

 

 

Plant Diagnostic Database

Cabbage Loopers (Trichoplusia ni)

                       

cabbagelooper

cabbagelooperadult

cabbagelooperdamage

cabbageloopereggs

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
Larvae feed at the base of developing cabbage heads inside the leaves, excreting a greenish, jellylike substance as they go.
Controls:
Pheromones:
Biological:

Traps are available to catch male cabbage looper moths.

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.

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Carrot Rust Fly

 

 

 

Plant Diagnostic Database

Carrot Rust Fly (Psila rosae)

                       

carrotlarvae sub

carrotrustflydamage

carrotrustfly

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Carrots, celery

Description:
Adults are housefly look-alikes with yellow heads. Larvae are yellow-white maggots.
Life Cycle:
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:
Biological: Cultural:
Apply parasitic nematodes to soil in late spring. Keep soil moist after application.


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.

 

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Carrot Weevil

 

 

 

Plant Diagnostic Database

Carrot Weevil  (Listronotus oregonensis)

                       

carrotweevil

carrotweevilcelery

carrotweevildamagelarva

carrotweevildamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Carrots, celery, parsnip

Description:
Adults are dark-brown snout beetles, 1/4 inch long. Larvae are creamy white grubs with reddish-brown heads.
Life Cycle:
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:
Cultural:
Biological: Botanical:

Use a 3-year rotation.  Cover new seed beds with floating row cover.

Parasitic nematodes can be somewhat effective against larvae. Apply when planting and water in. 

Check plants regularly; if more than one adult is seen per 10 foot row, spray pyrethrum.

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Cedar Apple Rust

 

 

 

Plant Diagnostic Database

Cedar Apple Rust (Gymnosporangium juniperi-virginianae)

                       

cedarapplerust

cedarapplerust2005

cedarapplerustleaves

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural: Mineral:

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.

Sulfur or copper soap sprays can be effective if sprayed preventatively in the spring when rust infection periods occur(wet with temperatures 60-70ºF).

 

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Cercospora Leaf Spot or Blight

 

 

 

Plant Diagnostic Database

Cercospora Leaf Spot or Blight (Cercospora spp.)

                       

cercosporaleafspot

cercospora

cercosporaleafspotrose

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
Spots with tan-pale, round centers and dark margins are visible. Symptoms appear on older leaves first and can cause defoliation.
Life Cycle:
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:
Cultural: Chemical:

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.

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).

 

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Cicadas

 

 

 

Plant Diagnostic Database

Cicadas:  Dog Day(Tibicen dorsata), Putnam's(Platypedia putnam)

                       

cicadadogday

cicadadogdayeating

cicadaputnams

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
None necessary.

 

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Codling Moth

 

 

 

Plant Diagnostic Database

Codling Moth(Cydia pomonella)

                       

codlingmoth

codlingmothlarva

codlingmothapple

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:

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:
Cultural: Biological:
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.

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: Traps:
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.

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.

 

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Colorado Potato Beetle

 

 

 

Plant Diagnostic Database

Colorado Potato Beetle  (Leptinotarsa decemlineata)

                       

coloradopotatobeetles

coloradopotatobeetlelarva

coloradopotatobeetleeggs

coloradopotatobeetledamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural:
Biological:

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 .

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

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Conifer Seed Bug

 

 

 

Plant Diagnostic Database

Conifer Seed bug(Leaffooted Bugs) (Leptoglossus occidentalis)

                       

coniferseedbug

coniferseedbugnymphs

coniferseedbugadults

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
None necessary.

 

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Cooley Spruce Gall Adelgid

 

 

 

Plant Diagnostic Database

Cooley Spruce Gall Adelgid  (Adelges cooleyi)

                       

cooleysprucegall

cooleysprucegallcut

cooleysprucegalldamage

cooleysprucegalleggs

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Spruce, douglas-fir.

Description:
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.
Life Cycle:

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:
Mechanical:
Chemical:

Pruning out galls is ineffective.

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.

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Corn Ear Worm

 

 

 

Plant Diagnostic Database

Corn Ear Worms  (Helecoverpa zea)

                       

cornearwormadult

cornearwormdamage

cornearwormdamage1

cornearwormlarva

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Beans, corn, peppers, tomatoes.

Description:
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.
Life Cycle:
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:
Traps:
Mechanical:

Blacklight traps catch male and female moths; pheromone traps catch only the males. Both traps are most effective as indicators of population levels.

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:

Biological:

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.
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.)

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Corn Root Worm

 

 

 

Plant Diagnostic Database

Corn Root Worm  (Diabrotica spp.)

                       

cornrootwormadult

cornrootwormbeetle

cornrootwormdamage

cornrootwormlarva

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Corn and related crops.

Description:
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.
Life Cycle:
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:
Cultural:
Chemical:

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.

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.

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Cottonwood Borer

 

 

 

Plant Diagnostic Database

Cottonwood Borer (Plectodera scalator)

                       

cottonwoodborer

cottonwoodborer1

cottonwoodborer2

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Cottonwood, other poplars and willow.

Description:
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.
Life Cycle:
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:
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.

 

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Cottonwood leaf Beetle

 

 

 

Plant Diagnostic Database

Cottonwood Leaf Beetle  (Chrysomela scripta)

                       

cottonwoodleafbeetle

cottonwoodleafbeetledamage

cottonwoodleafbeetlelarva

cottonwoodleafbeetleeggs

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Chemical:
If >50% of leaves are infested, spray Neem or Spinosad.

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Cucumber Beetles

 

 

 

Plant Diagnostic Database

Cucumber Beetles  (Acalymma & Diabrotica spp.)

                       

cucumberbeetlespotted

cucumberbeetlestriped

cucumberbeetles

cucumberbeetledamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Cucurbits (cucumber, squash), peas.

Description:
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. 
Life Cycle:

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:
Cultural:
Traps:

Grow resistant varieties, when possible

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:

Biological:

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. 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.

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Curly Top

 

 

 

Plant Diagnostic Database

Curly Top (Virus)

                       

curlytopacornsquash

curlytopbeans

curlytopbeets

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
This disease is viral. It causes dwarfing and leaf curl and yellowing; death will occur if very young plants are infected.
Life Cycle:
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:
Control leafhoppers. Remove diseased plants immediately. Use resistant cultivars when possible.

 

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Cutworms

 

 

 

Plant Diagnostic Database

Cutworms (Noctuidae spp.)

                       

cutwormadult

cutwormRedbackcutworm

cutwormvariegated

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Most young vegetable plants.

Description:
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.
Life Cycle:
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:
Cultural: Biological:
Till gardens in early spring or late fall to expose cutworms. Use transplants and protect with cardboard or plastic collars.

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: Traps:
Carbaryl mixed with bran baits. 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.

 

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Cytospora Canker

 

 

 

Plant Diagnostic Database

Cytospora Canker  (Valsa spp., Leucostoma spp.)

                       

cytosporacanker

cytosporacankercloseup

cytosporasprucedamage

cytosporacankeraspen

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Apple, Ash, Aspen, birch, boxelder, cottonwood, elm, linden, honey locust, maple, mountain ash, oak,poplar, sumac, willow, spruce, and stone fruits.

Description:

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.

Life Cycle:
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:
Cultural:
Biological:

 

  • 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.

 

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. 

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Damping Off

 

 

 

Plant Diagnostic Database

Damping Off (Pythium, Rhizoctonia, and other fungi)

                       

dampingoff2

Dampingoff

dampingoff1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Seeds and seedlings of many garden plants.

Description:
Seeds decay before emergence and seedlings fall over at the soil line and die. The disease causing fungi are common in garden soils.
Life Cycle:
Overwinters in plant debris and can survive on seeds. Excessive moisture encourages the disease.
Controls:
Biological: Cultural:
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).

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.

 

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Diamondback Moth

 

 

 

Plant Diagnostic Database

Diamondback Moth (Plutella xylostella)

                       

diamondbackmoth

diamondbackmothlarva

diamondbackmothpupa

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Biological: Chemical:
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.

Neem or Spinosad.

 

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Douglas Fir Beetle

 

 

 

Plant Diagnostic Database

Douglas Fir Beetle (Dendroctonus pseudotsugae)

                       

douglasfirbeetlegalleries

douglasfirbeetle

douglasfirbeetlesawdust

douglasfirbeetledamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Douglas Fir.

Description:
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.
Life Cycle:
Flight occurs May through June.  A second attack occurs in mid September.  Life cycle is 2 to 3 years.
Controls:
Cultural:
Pheromones:

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. 

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.

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Downy Mildew

 

 

 

Plant Diagnostic Database

Downy Mildew (Peronospora effusa)

                       

downdymildewcucurbit

downynpowderymildew

downymildewbrassica

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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. 
Life Cycle:
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:
Cultural: Chemical:
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.

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.

 

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Dutch Elm Disease

 

 

 

Plant Diagnostic Database

Dutch Elm Disease  (Ophiostoma ulmi)

                       

dutchelmdiseasesign

dutchelmdiseasebeetle

dutchelmdiseasesymptoms

dutchelmdiseasebark

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural:
Chemical:

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.

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.
 

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Earwig

 

 

 

Plant Diagnostic Database

Earwig (Forficula auricularia)

                       

earwig

earwigadult

earwigdamage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural: Botanical:
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.

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: Mechanical:
Diatomaceous earth and silica aerogel may be used to minimize populations indoors.  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.

 

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Elm Leaf Beetle

 

 

 

Plant Diagnostic Database

Elm Leaf Beetles  (Pyrrhalta luteola)

                       

elmleafbeetle

elmleafbeetlelarva

elmleafbeetledamge

elmleafbeetledamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Elm

Description:
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.
Life Cycle:
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:
Cultural:
Chemical:

Aerate soil around elm trees, mulch with wood chips or composted bark 2-3 inches deep.

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:

Biological:

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. 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.

 

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Engraver Beetle

 

 

 

Plant Diagnostic Database

Engraver Beetles (Ips species)

                       

beetleengraverIps

BeetleengraverIpsdamage

BeetlesengraverIpsgalleries

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Pine and sometimes spruce.

Description:
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.
Life Cycle:
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:
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. 

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. 

 

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Eriophyid Mites

 

 

 

Plant Diagnostic Database

Eriophyid  Mites (Family Eriophydae)

                       

EriophyidMtn.Ash

BlisterMite

Blistermiteaple

blistermitepopularbudgall

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Type: Hosts: Description:
Aculops tetranothrix Willow Red or yellow pouch galls
Appleleaf Blister Apple and crabapple species Rusty blisters on leaves
Chokecherry Finger Gall Chokecherry Green/red galls on the upper surface of leaf
Eriophyes celtis Hackberry Witches' brooms
Eriophyes negundi Boxelder Cottony growth and pouch in leaves
Honeylocust Rust Honeylocusts Rusty colored leaves
Linden Fingergall Lindens Small finger galls on leaves
Pear Russet Pears Russetting discoloration of fruits
Pearleaf Blister Pears Rusty blisters on leaves
Phyllocoptes didelphis Aspen Velvety red or brown growth on leaves
Phytoptus sorbi Mountain Ash Yellow pouch galls in leaves
Plum Fingergall Wild plum Green finger galls on lower leaf surface
Poplar Budgall Poplars, Cottonwoods Distortion of buds
Triestacus spp Pine Rosetted growth and stunted needles
Unknown Lilac Rusty colored leaves
Description:
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.
Life Cycle:
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:
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.

 

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European Corn Borer

 

 

 

Plant Diagnostic Database

European Corn Borer  (Ostrinia nubilalis)

                       

europeancornboreradult

europeancornborer

europeancornborerdamage

europeancornborereardamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Beans, Corn, peppers, rhubarb.

Description:
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.
Life Cycle:
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:
Traps:
Mechanical:

Blacklight traps catch male and female moths; pheromone traps catch only the males. Both traps are most effective as indicators of population levels.

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: Botanical:
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.

Spray Spinosad or pyrethrin in the evening.

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Fairy Ring

 

 

 

Plant Diagnostic Database

Fairy Ring (Marasmius spp)

                       

fairyring

fairyringmushrooms

fairyringsymptoms

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Turf, lawn, grass.

Description:

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. 

Life Cycle:
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:
Cultural: Chemical:
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. 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.

 

 

 

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Fall Webworm

 

 

 

Plant Diagnostic Database

Fall Webworm  (Hyphantria cunea)

                       

fallwebworm

fallwebwormadult

fallwebwormbranch

fallwebwormtent

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.

 

Life Cycle:
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:
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.

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Fir Broom Rust

 

 

 

Plant Diagnostic Database

Fir Broom Rust (Melampsorella caryophyllacearum)           

firbroomrustsym

firbroomrustsig

firbroomrustsign

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
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.

 

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Fireblight

 

 

 

Plant Diagnostic Database

Fireblight  (Erwinia amylovora)

                       

fireblight

fireblightsymp

fireblightsymptom

fireblightsyptom

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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. 
Life Cycle:

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:  
Cultural:
Chemical: Biological:

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

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.

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.)

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Flatheaded Borer

 

 

 

Plant Diagnostic Database

Flatheaded Borer (Chrysobothris mali)

                       

FlatheadedborerBuprestidae

flatheadedborerdamage

flatheadedborerlarva

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:

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.

Life Cycle:
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:
Cultural: Chemical:

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. 

Imidacloprid applied as a soil drench in the spring.

 

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Flea Beetles

 

 

 

Plant Diagnostic Database

Flea Beetles  (many species)

                       

fleabeetleadult

fleabeetledamage

fleabeetlestriped

fleabeetletuberdamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Type: Hosts: Description:
Cabbage Brassicas (cabbage, cauliflower, brussels sprouts, broccoli, kohlrabi, kale) Small, black & shiny
Tuber Potato Smallest(1/16") black to dark brown
Crucifer Brassicas (cabbage, cauliflower, brussels sprouts, broccoli, kohlrabi, kale), including weeds in the cabbage family such as winter cress and yellow rocket. Shiny metallic blue-black.
Pale striped Solanaceous crops (eggplant, pepper, potato, tomato), corn, beans, beets, curcubits, strawberry, lettuce, and weeds such as lambsquarters and pigweed Larger (1/8") with a pair of yellow stripes down its back.
Eggplant Solanaceous plants (eggplant, pepper, potato, tomato), especially eggplant. Small and black.
Description:
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.
Life Cycle:
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:
Cultural:
Biological:

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.

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.



 

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Forest Tent Caterpillars

 

 

 

Plant Diagnostic Database

Forest and Western Tent Caterpillars  (Malacosma disstria & M. californicum)

                       

forestcaterpillaradult

forestcaterpillardamage

forestcaterpillareggs

forestcaterpillarlarva

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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
Life Cycle:
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:

There are many insect and bird predators. Remove egg masses from tigs or other sites.  Remove and destroy nests. Bt(Bacillius Thuringensis) is effective on young larvae (< ¾"). 

Chemicals:   Neem extract and Spinosad spays are effective.

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Fusarium Wilt

 

 

 

Plant Diagnostic Database

Fusarium Wilt-Yellows  (Fusarium oxysporum)

                       

fusariumwiltbean

fusariumwilt

fusariumwiltplant

fusariumwiltsymptoms

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural:
Preventative: Biological:

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.

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.

 

Microbial Seed Treatments: Gliocladium virens(Soil Guard), Bacillus subtillus strains(Kodiak, Subtilex NG). 

 

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Gall Midges

 

 

 

Plant Diagnostic Database

Gall Midges  (various species)

                       

gallmidgehoneylocust

gallmidgelocust

midgeGoutyveingallmidge

PodgallMidge

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:
TYPE: Food preferences: Description:
Gouty Veingall Midge (Continaria negundinis)
Boxelder Thickening along the midrib of boxelder leaf. One generation per year.  No treatment needed.
Honeylocust Podgall Midge (Dsineura gleditschiae)
Honeylocust Larvae feed on developing leaves causing the pod like galls.  Galls darken, dry, and drop a few weeks after adults emerge. See below..
Life Cycle:
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:
Cultural:
Chemical:

Prune out infested growths.

Spinosad or horticultural oil applied as new foliage emerges.  May need to be applied several times.

 

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Grasshoppers

 

 

 

Plant Diagnostic Database

Grasshoppers  (Melanoplus spp.)

                       

grasshoppermigratory

grasshopperclearwinged

grasshopperredlegged

grasshoppertwostripe

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Type: Food preferences: Description:
Migratory This species can utilize almost any plant but prefers weedy forbs, wheat, and barley.  It aslo scavenges on ground litter, dead insects and dried manure. Adults of the migratory grasshopper are about three-fourths to one-inch long and are light brown with dark markings
Two-Striped This species feeds on many kinds of plants including grasses, forbs, trees, shrubs, and many cultivated crop plants.  Legumes and sunflowers are relished along with plant litter and dead insects.  It is commonly found as a pest of garden plants in suburban settings. Adults of the two-striped grasshopper are about 1.5 inches long, greenish-yellow or olive with two light yellow stripes running from the back of the head to the wing tips. 
Redlegged It can feed on just about any plant including grasses, legumes, and such diverse broadleaf plants as beets, cabbage, potatoes, and tobacco. Adults of the redlegged grasshopper are about ¾" long with a bright yellow ventral surface and the remainder of the body reddish-brown.
Clear-Winged This species feeds mainly on native and introduced grasses and will readily attack small grains.  Small amounts of forbs and legumes will also be consumed.  Adults of the clear-winged grasshopper are about three-fourths inch long, yellow to brown and marked with large, dark-brown spots
Description:
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.
Life Cycle:
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:
Cultural:
Biological:

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.

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:

Mechanical:

Baits containing carbaryl can be applied in a more selective manner.  Insecticides such as malathion, permethrin, bifenthrin can be use as a contact sprays.

Row covers (remay) can be used to cover valuable garden plants.



 

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Grey Mold

 

 

 

Plant Diagnostic Database

Grey Mold  (Botrytis cinerea)

                       

greymold

greymoldbean

greymoldsflowers

greymoldstrawberry

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Many vegetables, fruits including strawberries, and flower crops.

Description:
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.
Life Cycle:
The fungus overwinters on plant debris and organic matter in the soil.           
Controls:
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.

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Harlequin Bug

 

 

 

Plant Diagnostic Database

Harlequin Bug  (Margantia histrionica)

                       

harlequinbug

harlequinbugnymphs

harlequinbugeggs

harlequinbugdamage

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural:
Botanical:

Control weeds by removing, or mowing in crops or adjacent areas.  Attract native parasitic wasps and flies by planting small-flowered plants.

Spray with pyrethrin. 

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Hollyhock Rust

 

 

 

Plant Diagnostic Database

Hollyhock Rust (Puccinia malvacearum)

                       

hollyhockrust4

holyhockrust

hollyhockrust

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Hollyhock(Alcea rosea)

Description:
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.
Life Cycle:
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:
Cultural: Chemical:

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.

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.

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Imported Cabbage Worm

 

 

 

Plant Diagnostic Database

Imported Cabbage Worm  (Pieris rapae)

                       

importedcabbagewormlarva

importedcabbagewormadult

importedcabbagewormpupa

importedcabbagewormegg

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
 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.
Life Cycle:
The adult butterflies are usually active during the months of May and June. Larvae hatch and begin feeding, usually on the outside leaves.       
Controls:
Cultural:
Biological:

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.

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:

Chemical:

Cover plants with floating row cover(remay) before butterflies are present.

Spinosad or pyrethrin can be sprayed on larva.

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Ink Spot

 

 

 

Plant Diagnostic Database

Ink Spot (Ciborinia whetzelii)

                       

inkspot1

inkspot

inkspot2

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Aspens, cottonwoods and other poplars.

Description:
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.
Life Cycle:
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:
Cultural: Chemical:
Rake up and destroy infected leaves in the fall.  Increase spacing between trees to create better air circulation.

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.

 

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Iris leaf spot

 

 

 

Plant Diagnostic Database

Iris Leaf Spot (Mycosphaerella macrospora)

                       

Irisleafspot3

IrisLeafspotIris

Irisleafspot1

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Iris

Description:
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
Life Cycle:

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:
  • 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. 

 

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Late Blight

 

 

 

Plant Diagnostic Database

Late Blight  (Phytophthora infestans)

                       

lateblight

lateblightstem

lateblightplant

lateblighttomato

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Potato, tomato, occasionally eggplant.

Description:
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.
Life Cycle:
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:
Cultural:
Chemical:

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.

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.

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Leaf Rusts

 

 

 

Plant Diagnostic Database

Leaf Rusts  (various species)

                       

leafrustaspen

leafrustaspon

willowrust

leafrustribes

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:
Host: Alternate Host: Description:
Douglas Fir and Pines Aspen and Cottonwood The disease first appears on undersides of leaves or needles as yellow-orange pustles of spores.
Fir, Currant and Gooseberry Willow Leaf yellowing, browning, curling and drop may also occur.
Life Cycle:
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:
Cultural:
Chemical:

Rust diseases are managed with sanitation, or removal of fallen leaf debris.  Resisant varieties may be available.

Chemical control is rarely needed, however several fungicides such as Chlorothalonil and Myclobutanil are effective.

 

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Leafcutter Bees

 

 

 

Plant Diagnostic Database

Leafcutter Bees (Megachile species)

                       

leafcutter

leafcutterbee

leafcutterbeedamage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
Adult leafcutter bees resemble dark, robust honeybees.
Life Cycle:
Leafcutter bees are solitary bees. The female cuts leaf disks to create individual thimble shaped rearing cells packed with pollen.
Controls:
There is no legal control of the bees since they are important pollinators and thus protected. However, hot pepper wax reduced feeding in one grasshopper study and may help to repel leafcutter bees if sprayed several times during their active period.

 

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Leafhoppers

 

 

 

Plant Diagnostic Database

Leafhoppers  (many species)

                       

leafhopper

leafhopperdamage

Leafhopperinjury

leafhopperpotato

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
Type: Food preferences: Descripti
Sixspotted Leafhopper An extreemly wide range of plants including small grains, turfgrasses, many vegetables, and flower crops. Adults are smoky green, wedge-shaped, 3/16 inch long, and 6 spotted.
Potato Leafhopper A wide variety of plants, particularly legumes such as bean and alfalfa.  Potato, raspberry, and several trees including maple, birch, and apple are also common hosts. Adults are yellow green, spindle-shaped, 1/8 inch long, and winged. Nymphs are smaller and wingless.
Rose Leafhopper Rose and Rubus species are overwintering hosts.   Dogwood, oak, elm, hawthorn, apple poplar, maple are among the summer hosts. Overwintering eggs on canes are dark, pimple-shaped spots. Cream colored nymphs hatch in spring, feed on leaf undersides, then adults move to oaks, elms and other ornamentals.
Virginia Creeper Leafhopper It feeds on grape, virginia creeper, elm and boston Ivy. Adults are pale, whitish, wedge-shaped and 3/16" long. They emerge when temperatures are 60 - 65° F. for several days.
Description:
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.

Life Cycle:
Depends on the species.
Controls:
Chemical: Mechanical:

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.

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.

 

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Leafminers

 

 

 

Plant Diagnostic Database

Leafminers  (multiple species)

                       

leafmineradult

leafminercolumbine

leafminerspinach

leafminnerbirchdamage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
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.

Description:
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.
Life Cycle:
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:
Biological:
Chemical: Mechanical:

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.

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. 

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.

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leafrollers

 

 

 

Plant Diagnostic Database

Leafrollers  (many species)

                       

Leafroller

leafrolleradultOB

Leafrollereggs

Leafrollerinjurytoleaves

 

 

 

 

 

                                                                                                                                                                                              
Hosts:
TYPE: Food preferences: Description:
Boxelder Leafroller Boxelder 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. 
Fruittree Leafroller Apple, pear, plum, cherry, raspberry, currant, ash, boxelder, elm, linden, poplar, willow, locust, rose, and oak. 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.
Oblique-banded Leafroller Fruit trees and ornamental trees and shrubs. 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. 
Life Cycle:
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:
Botanical:
Biological: Chemical

Bacillus thuringiensis (Bt-K). Treat newly hatched larvae, before leaves curl. This works best when temperatures are warm (>50ºF). 

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.

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.

 

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Lilac / Ash Borer

 

 

 

Plant Diagnostic Database

Lilac / Ash Borer (Podoesia syringae)

                       

Ashborer

ashborerdamage

Ashborerlarva

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Ash and lilac

Description:
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.
Life Cycle:
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:
Cultural:  Chemical:
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. Trunk sprays of permethrin can be applied 2 weeks after the adults are caught in pheromone traps.

 

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Marssonina Leaf Spot/Blight

 

 

 

Plant Diagnostic Database

Marssonina Leaf Spot/Blight (Marssonina populi)

                       

Marsinoninia BlightbySarahHolden

marssoniablight

marssonialeafblight

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Aspen, cottonwoods, and poplars.

Description:
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.
Life Cycle:
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:
Cultural: Mineral:
Rake up and destroy infected leaves. Keep irrigation water off leaves.

Spray a copper based fungicide as buds begin to break. If weather is wet and warm, protect developing leaves with sulfur or chlorothonanil.

 

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Melting Out

 

 

 

Plant Diagnostic Database

Melting Out (Drechslera poae)

Leaf spot

meltingout3

meltingout

meltingout2

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

kentucky bluegrass, annual bluegrass, tall and fine leafed fescues

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

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.

 

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Mosaic Virus

 

 

 

Plant Diagnostic Database

Mosaic Virus  (many species)

                       

1436025corn

mosaicviruscorn

mosaicvirussquash

mosaicvirustobacco

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:
TYPE: Food preferences: Description:

Maize Dwarf Mosaic Virus
Corn Chlorotic spots that elongate on young leaves.

Squash Mosaic Virus
Cucurbits
(Cucumber, squash).
Patches of light green or yellowish colored leaf tissue.

Tobacco Mosaic Virus
Cucurbits
(cucumber, squash), solanaceous crops (eggplant, pepper, potato, tomato), celery, corn.
Yellow/green mottling in plant leaves and/or puckering and distortion of leaves.
Life Cycle:
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:
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.

 

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Mountain Pine Beetle

 

 

 

Plant Diagnostic Database

Mountain Pine Beetle ( Dendroctonus ponderosae)                    

beetlemountainpine

beetlemountainpinepitchtube

beetlemountianpinetreetrunk

beetlemountainpinelarva

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

All native and introduced species of pine.

Description:
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.
Life Cycle:
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:
Cultural: Chemical:  Trapping:
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.

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.


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.

 

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Needle Casts

 

 

 

Plant Diagnostic Database

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

                       

needlecaslophodermium

needlecastelytrodermapine

needlecastlophodermella

needlecastmycosphaerella

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description & Life Cylcle:
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.

 

Controls:
Cultural:
Chemical:

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.

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. 

 

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Peach Leaf Curl

 

 

 

Plant Diagnostic Database

Peach Leaf Curl (Taphrina deformans)

                       

peachleafcurl1

peachleafcurl

PeachLeafCurl2

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Peach (other species of Taphrina may affect plums).

Description:
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.
Life Cycle:
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:
Cultural: Chemical:
Prune out infected branches/leaves. Rake and destroy infected leaves in the fall.  Plant resistant cultivars.

Spray copper as buds start to swell in the spring.

 

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Pear Psylla

 

 

 

Plant Diagnostic Database

Pear Psylla (Cacopsylla pyricola)

                       

pearpsylla

pearpsylladamage

pearpsyllanymph

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Pear

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

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.

 

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Pear Sawfly

 

 

 

Plant Diagnostic Database

Pear Slug - Pear Sawfly (Caliroa cerasi)

                       

pearsawflyadult

pearsawflydamage

pearsawfly

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Chemical: Cultural:

Spray with insecticidal soap if >50% of leaves have feeding injury.

Wash off larvae with strong stream of water.

 

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Petiole Gall Aphids

 

 

 

Plant Diagnostic Database

Petiole Gall Aphid

                       

petiolegallaphiddamage

Aphidpetiolegall

petiolegallaphid

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Poplars, cottonwoods

Description:
Round hollow galls form on leaf petioles. Infested leaves may drop prematurely in late summer. 
Life Cycle:
The petiole gall aphid winters as egges 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:
They are not a serious problem on Populus spp. and control is not necessary for these species.

 

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Phytophthera Root Rot

 

 

 

Plant Diagnostic Database

Phytophthera Root or Crown Rot (Phytophthora spp.)

                       

phytophthorarootrotsymptoms2

phytophthorarootrotsymptoms

phytophthorarootrotsymptoms1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
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.

 

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Poplar Borer

 

 

 

Plant Diagnostic Database

Poplar Borer  (Saperda calcarata)

                       

aspenborersawdust

borer2

Borerinaspen1

borerpoplarbug

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

Aspen, cottonwood, poplars, willow.

Description:
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.
Life Cycle:
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:
Cultural:
Chemical: Biological:

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.

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.

Insertion of 'borer crystals' (paradichlorobenzene) or injections of insect parasitic nematodes (Steinernema species) into active borer tunnels have given partial control of larvae.

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poplar Vagabond Aphid

 

 

 

Plant Diagnostic Database

Poplar Vagabond Aphid (Mordwilkoja vagabunda)

                       

polarvagaphid

poplarvagaphid1

poplarvagaphid2

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Aspen, cottonwoods, and other poplars

Description:
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.
Life Cycle:
The vagabond aphid uses two hosts during its life cycle.  The overwintering stage are egges 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:
Galled leaves tend to remain on trees and may not be visable until after normal leaf fall.  Galling is concentrated on the upper third of the tree.  Controlls have not been identified.  Dormant applications of horticultural oils should kill overwintering eggs.

 

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Potato Scab

 

 

 

Plant Diagnostic Database

Potato Scab (Streptomyces species)

                       

potato1scab

potatoscab

potatoscab2

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Potato and sometimes red beets.

Description:
Tuber surfaces have  areas that are brown, roughened, raised or pitted, and warty-looking.
Life Cycle:
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:
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'.

 

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Powdery Mildew

 

 

 

Plant Diagnostic Database

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

                       

powderymildewmaple

powderymildewsymptoms

powderymildewspores

powderymildewapple

 

 

 

 

 

                                                                                                                                                                                              
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.

Description:
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.
Life Cycle:
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:  
Biological:
Chemical:
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.


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.

 


 

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Raspberry Crown Borer

 

 

 

Plant Diagnostic Database

Raspberry Crown Borer (Pennisetia marginata)

                       

raspberrycrownborerlarva

raspberrycrownborer

raspberrycrownborerplant

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

 All rubus species including raspberry.

Description:
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.
Life Cycle:
Eggs 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:
Cultural: Chemical:
Remove alternate hosts (wild rubus species). Prune out and destroy infested canes in the fall. Keep plants properly irrigated and vigorous.

Insecticides drenched over the crowns in early spring just before bud break may diminish a portion of the larvae. Least-toxic option is pyrethrin.

 

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Red Thread

 

 

 

Plant Diagnostic Database

Red Thread (Laetisaria fuciformis)

                       

redthread1

redthread3

redthread2

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
Red thread is expecially 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.
Life Cycle:
Cool (40-70 degrees), wet conditions (heavy dew, light rain, and fog) are favorable for developement.  Red thread is most severe during periods when grass is growing slowly as a result of low tempertures, lack of sunlight, drought, inadequate fertility and other diseases.      
Controls:
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 resisant cultivars are available.

 

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Redhumped Caterpillar

 

 

 

Plant Diagnostic Database

Redhumped Caterpillar (Schizura concinna)

                       

redhumpedcaterpillardamage

redhumpedcaterpillar

redhumped1caterpillar

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
Caterpillars with a pronounced reddish hump behind the head.
Life Cycle:
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:
Control is rarely needed. Cosmetic injury only.  If needed products such as Bacillus thurinensis or spinosad would be effective.

 

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Rhizoctonia

 

 

 

Plant Diagnostic Database

Rhizoctonia (Rhizoctonia spp.)

                       

rhizoctoniafruit

rhizoctoniaroot

rhizoctoniaplant

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Vegetables, flowers, woody species.

Description:
This fungus causes damping-off-like symptoms on seedlings, root rots, and above-ground stem cankers and fruit rots.
Life Cycle:
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:
Biological: Cultural:
Treat seed with Bacillus subtilis (Actinovate, Kodiak, RootShield Granules).

 

Wait to plant at optimum germination temperatures. Use plastic mulch to prevent fruit contact with soil. Use a 3-year rotation.

 

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Root Maggots

 

 

 

Plant Diagnostic Database

Root Maggots  (Delia spp.)

                       

rootmaggot1

rootmaggot11

rootmaggotcabbage

cabbagerootmaggotflymedcabbagekengray

 

 

 

 

 

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

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. 

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.


 

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Root-knot Nematodes

 

 

 

Plant Diagnostic Database

Root-knot Nematodes (Meloidogyne spp.)

                       

rootknotnematodes1

rootknotneamatodes

rootknotnematodes2

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Vegetables, flowers, woody shrubs and weeds.

Description:
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.
Life Cycle:
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:
Biological: Cultural:
Apply parasitic nematodes.

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.

 

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Rose Curculio

 

 

 

Plant Diagnostic Database

Rose Curculio (Merhynchites bicolor)

                       

rosecurculi

rosecurculio

rosecurculio1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Rose

Description:
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.
Life Cycle:
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:
Cultural: Biological: Botanical:
 Pick off adults Parasitic nematodes may help to control larvae before they emerge in the spring. Fall application is best in Western Montana.

Neem or pyrethrum can be sprayed on larvae feeding on flowers. 

 

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Rose Gall Wasp

 

 

 

Plant Diagnostic Database

Rose Gall Wasp (Diplolepsis spp.)

                       

rosegallwaspdamage

rosegall1

rosegallwaspdamage1

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Wild and cultivated roses.

Description:
Adults are tiny wasps; larvae are tiny, whitish, and maggot-like.
Life Cycle:
Immature wasps overwinter in galls on rose stems, leaves, buds and roots. Wasps emerge in the spring.      
Controls:
Prune out and destroy galls as they appear in late summer and fall.

 

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Rose Mosaic Virus

 

 

 

Plant Diagnostic Database

Rose Mosaic Virus

                       

rosemosaic

rosemosaicv

rosemosaicvirus6

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Rose

Description:
Rose leaves are distorted, crinkled, with white to yellow discoloration.
Life Cycle:
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:
Cultural:

Use resistant cultivars. Remove affected branches or plants. Sterilize pruning tools with a 10% bleach solution.

 

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Rose Rust

 

 

 

Plant Diagnostic Database

Rose Rust (Phragmidium mucronatum)

                       

roserust1

Roserust2

roserust3

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Rose

Description:
Orange spots are present on leaves. Spots on canes are orange, but become black in the fall and winter.
Life Cycle:
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:
Biological: Cultural:
Bacillus pumilis strain (sonata).

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. 

 

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Rose Stem Girdlers

 

 

 

Plant Diagnostic Database

Rose Stem Girdler/Bronze Cane Borer (Agrilus aurichalceus)

                       

rosestemgirdler

rosestemgirdlera

rosestemgirdler1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Rose, raspberry, currant, gooseberry.

Description:
The adult beetles are about ½ inch long, all black with a coppery thorax.
Life Cycle:
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:
Prune out and destroy infested canes in late winter/early spring.

 

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Sap Beetles

 

 

 

Plant Diagnostic Database

Sap Beetle (several species)

                       

sapbeetle

sapbeetlelarva

sapbeetledamage

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Corn

Description:
Adults are 3/16 inch long, gray/black, oblong beetles; larvae are worm-like.
Life Cycle:
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:
Mechanical: Cultural:
If populations are small, they can be handpicked.

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 reisistant.

 

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Sapsuckers

 

 

 

Plant Diagnostic Database

Sapsuckers (Sphyrapicus varius)

                       

sapsucker1

sapsucker

sapsuckerdamage

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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. 
Life Cycle:
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:
Cultural: Exclusion:
Sapsuckers are protected by the Federal Migratory Bird Treaty Act! 

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: Visual Frightening Devices:
Make loud noises using a cap pistol, banging garbage can lid, or commercial noise-producing 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. 

 

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Sawfly

 

 

 

Plant Diagnostic Database

Sawfly (Macremphytus tarsatus)

                       

sawflydogwood

SawflyMacremphtustarsatus

sawflydogwood1

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Dogwood

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

 

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Scale

 

 

 

Plant Diagnostic Database

Scale (multiple species)

                       

oyster

Scalepine1

ScaleCottonyscale

scalelecanium

 

 

 

 

 

                                                                                                                                                                                              
     
TYPE: HOSTS:  DESCRIPTION:
Cottony Cushion Scale-Icerya purchasi and actylopius sp.    Woody ornamentals Adult female scale has a fluted cottony egg sac secreted from the body of the scale. 
Lecanium Scale - Lecanium corni                                        Fruit and decidious trees and shrubs 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.
Oystershell Scale - Lepidosaphes ulmi                               Lilac, poplar, willow, privet, sumac, aspen, green ash & fruit trees Pale yellow, tiny crawlers emerge May - June.
Scales are grey-brown and shaped like a miniature oyster. There is one generation per year.
Pine Needle Scale - Chionaspis pinifoliae                            Conifers, especially mugo pine 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. 

 

Life Cycle:
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:
Cultural:
Chemical: Biological:

Rub scale off plants by hand with a glove or toothbrush.  Prune off infestations. 

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. 

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

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Septoria Leaf Spot

 

 

 

Plant Diagnostic Database

Septoria Leaf Spot (Septoria musiva)

                       

septoria

septorialeafspottomato2

septorialeafspot

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Vegetables: Woody Plants:
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.

Rake and destroy infected leaves in the fall. Apply sulfur during warm, wet spring weather

 

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Shot Hole Disease

 

 

 

Plant Diagnostic Database

Shot Hole Disease-Coryneum Blight (Wilsonomyces carpophilus)

                       

shotholeearly

ShotholeonCherry

shotholeonfruit

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural: Chemical:
Prune out dead branches and twigs.  Do not let sprinkler irrigation water wet tree foliage and fruit.

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.

 

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Shothole Borer

 

 

 

Plant Diagnostic Database

Shothole Borer (Scolytus rugulosus)

                       

shotholeborer

shotholeborerdamage

shotholeborergallery

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
The adults are small 1/10" gray-black beetles that may begin to emerge in late April or May but can be subsquently be found throughout the growing season.  
Life Cycle:
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:
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 potenial hazard of attack.

 

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Smut

 

 

 

Plant Diagnostic Database

Smut (Ustilago maydis)

                       

smut

smutsign

smutcorn

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:

Cultural:
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.

Grow resistant varieties.  Rotate crop for 3-4 years.

 

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Snailcase Bagworm

 

 

 

Plant Diagnostic Database

Snailcase Bagworm (Apterona helix)

                       

snailbagworm3

snailcasebagworm

snailcasebagworminfest

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

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

Description:
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
Life Cycle:
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:

Mechanical:
Control is very difficult since the insect is inside a protective case. Fortunately, this pest does little damage in western Montana.

Using a pressure-washer with soapy water will remove bagworms from buildings.

 

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Snow Mold

 

 

 

Plant Diagnostic Database

Snow Mold (Typhula incarnata)

                       

snowmold

snowmold1

snowmold2

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

All cool season turfgrasses, especially perennial ryegrass.

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

 

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Sooty Mold

 

 

 

Plant Diagnostic Database

Sooty Mold (Various genera and species of fungi)

                       

sootymold

sootymold1

sootymoldonbranch

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
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.

Description:
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.
Life Cycle:
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:

Wash off with soapy water. Repeat applications are necessary.

 

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Spider Mites

 

 

 

Plant Diagnostic Database

Spider Mites  

                       

mitespidersprucedamage

mitespiderdamage

mitesspiderdamage

mitesspidertwospot

 

 

 

 

 

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

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.

Several organisms prey on spider mites in field settings; minute pirate bugs and predatory species of mites are among the most important.

Mechanical: Chemical:
Overhead watering - and purposeful hosing of plants with water in a garden setting - can dislodge and kill many spider mites.

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. 

 

 

 

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Spittlebugs

 

 

 

Plant Diagnostic Database

Spittlebugs (Clastoptera juniperina)

                       

spittlebug

spittlebugjuniper

spittlebugs

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Wash off with soapy water.  Spittlebugs are not a serious concern in the landscape.

 

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Squash Bug

 

 

 

Plant Diagnostic Database

Squash Bug  (Anasa tristus)

                       

squashbug

squashbugdamage

squashbugeggs

squashbugnymphs

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Cucurbits (cucumber, squash).

Description:
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.
Life Cycle:
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:
Mechanical:
Biological:

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.

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.

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Squash Vine Borer

 

 

 

Plant Diagnostic Database

Squash Vine Borer  (Mellitta satyriniformis)

                       

squashvineborer

squashvineborerlarva

squashvineborerlarva2

squashvineborerwilt

 

 

  • Hosts
  • Life Cycle

 

 

  • Description
  • Controls

 

                                                                                                                                                                                              
Hosts:

Cucurbits (cucumber, squash).

Description:
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.
Life Cycle:
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:
Cultural:
Mechanical:

Grow resistant varieties, when available.

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.

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Tarnished Plant Bug

 

 

 

Plant Diagnostic Database

Tarnished Plant Bug  (Lygus lineolaris)

                       

tarnishedplantbug

tarnishedplantbugdamage

tarnishedplantbugdamage2

tarnishedplantbugdamage1

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
Cultural:
Botanical: Mechanical:
Till after harvest. Attrack native predators (bigeyed bugs, damsel bugs, pirate bugs) with groundcovers and pollen plants.

Neem or pyrethrin, sprayed in the evening with a soap spreader-sticker (1 oz/gal water), will control higher infestations.

White sticky traps may be used to control low infestations

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Tussock Moth

 

 

 

Plant Diagnostic Database

Tussock moth  (Orgyia pseudotsugata)

                       

tussockmoths

tussockmothlarva

tussockmothdamage

tussockmothdamage1

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
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.
Life Cycle:
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:
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. 

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Ugly Nest Caterpillars

 

 

 

Plant Diagnostic Database

Ugly Nest Caterpillars  (Archips cerasivorana Fitch)

                       

uglynestcaterpillar

uglynestcaterpillar1

uglynestcaterpillarnest

uglynestcaterpillareggs

 

 

 

 

 

                                                                                                                                                                                              
Hosts:

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

Description:
Caterpillars are olive green, reaching 3/4 inch long when mature and found clustered in groups.
Life Cycle:
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:
Natural predators keep this pest at low populations. Bt (Bacillus thuringensis) is effective on younger larvae.

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Venturia Shoot Blight

 

 

 

Plant Diagnostic Database

Venturia Shoot Blight (Venturia populina)

                       

venturiashootblight1

venturia

venturiashootblight

 

 

  • Hosts
  • Life Cycle

 

 

 

                                                                                                                                                                                              
Hosts:

Aspen, cottonwoods, and poplars.

Description:
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.
Life Cycle:
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:
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.

 

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Verticillium Wilt

 

 

 

Plant Diagnostic Database

Verticillium Wilt  (Verticillium species)

                       

verticilliumwilt

verticilliumwiltpotato