Plants
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Beadlike galls on both sides of leaf surfaces | Eriophyid mite |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Frothy spittlemass | Spittlebugs (Clastoptera juniperina) |
Cottony material | Alder aphid |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Discolored areas, dead bark containing small pimple-like fruiting bodies | Cytospora canker (Valsa spp.,Leucostoma spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Large holes chewed in leaves | Speckled green fruitworm, Redhumped caterpillar (Schizura concinna) , or Forest tent caterpillar. |
Silken tents produced | Western tent caterpillar or Fall webworm(Hyphantria cunea) |
Caterpillar living within a case | Snailcase bagworm (Apterona helix) |
Terminal leaves curled and tied together with silk | Fruittree leafroller or Obliquebanded leafroller |
Skeletonized leaves | Apple and thorn skeletonizer (Choreutis pariana) or Apple flea beetle (Phyllotretaspp.) |
"Shothole" feeding wounds in leaf, usually with sucker growth | Apple flea beetle (Phyllotreta spp.) |
Raised leafmines | Western tentiform leafminer (Phyllonorycter elmaella) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Pale green or yellow leaves | Iron chlorosis. See Nutrient Deficiencies |
Rust orange spots | Juniper rusts |
Black mold on surface of leaf | Apple scab (Venturia inaequalis) |
Rusty blisters or scabby patches on leaves | Blister mites. See Eriophyid Mites |
Bronzing of leaves | Two-spotted spidermite or McDaniel spider mite |
Curling distortions of new growth in spring | Rosy apple aphid |
Blackened and wilted leaves | Fireblight (Erwinia amylovora) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twigs shredded by a line of multiple punctures | Cicada oviposition wounds |
Blackened, wilting, and crooked tips | Fireblight (Erwinia amylovora) |
Black beetle tunneling, with small exit holes | Shothole borer |
Scales on twigs | Oystershell scale or European fruit lecnium |
Cottony insects on twigs | Woolly apple aphid or Mealbugs |
Discolored areas, dead bark containing small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Boring into trunk | Flatheaded appletree borer - (Chrysobothris mali) |
Bark beetle tunneling, small exit holes | Shothole borer |
Cottony insects on trunk and/or roots | Woolly apple aphid |
Internal decay and/or shelf-like fruiting structures (conks) | Decay fungus |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytophthoraspp.) |
Galls at ground line | Crown gall |
Affecting Roots: | |
Signs or Symptoms | Cause |
White root decay and white mycelial fans between bark and wood | Armillaria root disease (Armillaria spp.) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Tunneling in fruit | Codling moth (Cydia pomonella) |
Scarring or scabbing of fruit | Fruittree leafroller, Hail injury, or Apple scab (Venturia inaequalis) |
Pitted, scarred fruit | Tarnished Plant Bug (Lygus lineolaris) |
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Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc. (Prunus spp.)
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Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Tree decline in vigor | Phytophthora root rot (Phytophthoraspp.), Cytospora Canker (Valsa spp.,Leucostoma spp.), or Verticillium wilt(Verticillium spp.) |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed, no associated webbing | Pearslug (Caliroa derasi) |
Upper surface of the leaf skeletonized | Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer |
Webbing associated with chewing | Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum) |
Leaves with small, circular holes | Shot hole disease |
White flecking injuries | White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Leaves yellow | Iron chlorosis or X-disease |
Leaves with small, pouch or finger-like projections | Fingergall mites (Phytoptus species) |
New leaves curled | Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi) |
New leaves curled and thickened and red/purple | Peach leaf-curl disease |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Black galls on branches | Black knot of cherry (Apiosporina morbosa) |
Stem decay and/or hoof-shaped fruiting body (conk) | Decay fungus (Phellinus pomaceus) |
Scales | Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi) |
Small pinhead-sized exit holes in branches | Shothole borer (Scolytus rugulosus) |
Branches die back | Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus) |
Gumming and dark colored branches | Shothole borer (Scolytus rugulosus), or Cytospora canker (Valsa spp.,Leucostoma spp.) or Bacterial Blight (Pseudomonas syringae) |
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytopthora sp.) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Fruit tunneled | European earwig (Forficula auricularia L.) |
Fruit with sunken, corky areas | Plant bug (Lygus species), Hail injury, or Boxelder bug (Boisea trivittata) |
Puncture wounds in fruit | Bird damage (Robins, finches, etc.) |
Chokecherry fruit enlarged, hollow | Chokecherry gall midge (Contarinia virginianae) |
Maggots in cherry fruit | Western cherry fruit fly (Rhagoletis indifferens Curran |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed: normal chewing injuries, primarily confined to leaf edges | Browheaded AshSawfly (Tomostethusmulticinctus); Forest tent caterpillar (Malacosoma dissetria); Fruittree leafroller (Archips argyrospilus) |
Smooth semicircular cuts made on leaf edge | Leafcutter Bees (Megachile spp.). |
Blackened spotting of leaves | Ash Anthracnose (Apiognomonia spp.) |
Leaflets being distorted and/or killed back | Ash plant bug (Tropidosteptes amoenus) |
Flecking wounds on leaves | Ash plant bug (Tropidosteptes amoenus) or Lacebug (Corythuca spp.) |
Leaves bronzed: “Brittle-leaf†condition | Eriophyid mites |
Leaflets thickened and curled at midrib | Ash midrib gall midge (Contarinia canadensis) |
Leaves tightly curled and thickened | Leafcurl ash aphid (Prociphilus fraxinifolii) |
General distortion of leaf, with thickened veins | Herbicide injury |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Wilting of portions of tree: originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twig dieback with small exit holes or ventilation holes visible | Ash bark beetles (Hylesinus spp.) |
Twig dieback with small pimple-like fruiting bodies (pycnidia) in the bark | Cytospora canker (Valsa spp., Leucostoma spp.) |
Witches' brooming symptoms | Ash yellows (Phytoplasma) |
Scales | Oystershell scale (Lepidosaphes ulmi) or European fruit lecanium (Parthenolecanium corni) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Tunneling in trunk | Lilac/Ash borer, Banded ash clear wing, (Podosesia syringa); Ash bark beetles (Hylesinus spp.); Redheaded ash borer(Neoclytus acuminatus) |
Masses of caterpillars resting on bark | Forest tent caterpillar (Malacosoma disstria Hubner) |
Discolored areas and dead bark containing small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood/slime flux |
Large, dead areas of bark on southwest side of trunk | Winter sunscald |
Open wounds, internal decay, swollen areas on stem | Stem decay fungi (Perenniporia fraxinophila, Phellinus punctatus, and various fungal genera) |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (Perenniporia fraxinophila, Phellinus punctatus, and various fungal genera) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Flowers: | |
Signs or Symptoms: | Cause: |
Distorted flowers | Ash flower gall mite (Eriophyes fraxiniflora) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow leaves, slow growth | Nitrogen deficiency. |
Yellow leaves, dwarfed plants, plants form bushy rosettes. | Asparagus aphids |
Yellow leaves, wilting, dieback of crown. | Fusarium wilt (Fusarium oxysporum) |
Foliage turns reddish brown and drops; small reddish spots on main stems and branches. | Rust |
Defoliated plants/deformed spears. | Several insect pests cause this kind of injury, including Asparagus beetles |
Affecting Spears: | |
Signs or Symptoms | Cause |
Chewed stalks at soil line, seedlings clipped off at soil line. | Cutworms (Noctuidae spp.) |
Large lesions at base of spears or below soil line; small spears. | Fusarium wilt(Fusarium oxysporum) |
Spears turn brown near soil line. | Phytopthora crown rot (Phytophthora spp.) |
Bracts of spears are spread out. | Feathering caused by high temperatures (>85° F.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves curled | Large aspen tortrix (Choristoneura conflictana) |
Leaves curled with tent of silk produced | Western tent caterpillar (Malacosoma fragilis) |
No curling or silk associated with injury | Forest tent caterpillar (Malacosoma disstria Hubner), Redhumped caterpillar(Schizura concinna), Cottonwood leaf beetle (Chrysomela scripta), or Sawflies(cimbidae) |
Masses of dark, spiney caterpillars on leaves | Spiny elm caterpillar [Mourning Cloak Butterfly] (Nymphalis antiopa) - No significant damage. |
Leaves spotted: Young leaves blackened | Shoot blight (Venturia tremulae) or Frost injury |
Black irregular spots on leaves | Septoria leaf spot and canker (Septoria populicola) |
Dark round spot which drops out of leaf, leaving shothole appearance | Ink spot (Ciborinia whetzelii) |
Black spots with yellow margins | Marssonina blight (Marssonina populi) |
Rust or orange colored spots | Conifer-aspen rust (Melampspora spp.) |
Underside spots with small depressions and patches of brown leaf hairs | Eriophyid mites |
Leaves generally distorted or thickened; whole leaf or set of leaves so distorted | Poplar vagabond aphid(Erisomatidae spp.) |
Edge of leaf folded into a series of ridges | Eriophyid mites |
Red, thickened folds along leaf veins | Gall midge |
Leaves with serpentine, silvery tunneling | Aspen leafminer (Phyllocnistis populiella) |
Sucking insects on leaves | Clear-winged aspen aphid (Chaitophorus populifoliae) or Leafhoppers |
White powdery material on upper or lower surface of leaf | Powdery mildew (Erysiphe cichoracearum) |
Yellowed leaves | Root damage caused by under or over watering or Iron chlorosis |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twig dieback; Shoot curled into a shepherd’s crook | Shoot blight (Venturia tremulae) |
Meandering tunnels under bark | Flatheaded borer Agrilus spp. |
Twig dieback with small pimple-like fruiting bodies (pycnidia) in the bark | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Scales on bark | Oystershell scale (Lepidosaphes ulmi) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Areas of dead bark, with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Small (1/6 - in) gray or brown oystershell shaped objects on bark | Oystershell scale (Lepidosaphes ulmi) |
Rounded and often rough swellings on branches | Aspen gall (Diplodia tumefaciens) |
Oozing liquid from wounds with clear to white oozing or frothy malodorous liquid | Bacterial wetwood/slimflux |
Orange staining ooze | Poplar borer (Saperda calcarata) |
Cottony growth on branches and/or trunk | Woolly aphid |
Swellings in branches or trunk | Poplar borer (Saperda calcarata) |
Tunneling with coarse sawdust often forced from opening | Poplar borer (Saperda calcarata) |
Regular rows of holes in trunk | Sapsuckers |
Open wounds, internal decay, or swollen areas in stem | Stem decay fungi (Phellinus tremulae, Ganoderma applanatum, and other fungal genera) |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (Phellinus tremulae, Ganoderma applanatum, and other fungal genera) |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms: | Cause: |
White root decay with white mycelial fans between bark and wood | Armillaria root disease (Armillaria mellea) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves being chewed | Fruittree leafroller (Archips argyrospila) or Speckled green fruitworm (Orthosia hibisci) |
Small pouch galls form on leaf surface | Linden fingergall mite (Eriophyid mite) |
Velvety patches on underside of leaves (littleleaf linden) | Linden fingergall mite (Eriophyid mite) |
Pale green or yellow leaves | Iron chlorosis |
Leaves strongly cupped | Herbicide injury. |
Aphids | Linden aphid (Myzocallis tiliae) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Large cottony insect develops in late spring | Cottony maple scale (Pulvinaria innumerabilis) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, curling leaf margins, wilted plants; flowers and pods drop | Large aspen tortrix (Choristoneura conflictana) |
Yellow, distorted new growth. | Tarnished plant bug (Lygus pratensis) |
Yellow leaves, slow growth | Nitrogen deficiency |
Curled, yellow, withered leaves | Bean aphids, Bean mosaic, or Curly top |
Small reddish-brown specks, especially on leaf undersides; leaves yellow and drop | Rust |
White, stippled leaves, which later become bronzed, stunted growth | Mites |
Meandering tunnels in leaves | Leaf miners |
Puckered leaves curl downwards; plants stunted | Flea beetles (Phyllotreta spp.) |
Affecting Seeds, Seedlings, or Roots: | |
Signs or Symptoms | Cause |
Stems rot near soil line and plant collapses; seeds do not germinate | Damping off |
Poor germination, deformed, spindly seedlings with killed growing point | Seed corn maggots |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Blossoms drop | Excessive heat or rain, or Western flower thrips (Frankliniella occidentalis) |
Pitting and russeting of pods | May be due to chilling injury |
Water-soaked or brown patches on pods; yellow, blotched seeds | Bacterial blight (Pseudomonas syringae) |
Holes chewed in pods | Caused by several worms including the following: Cabbage looper, Beet armyworm (Euxoa auxiliaris) , Corn earworm (Heliothis zea) , or European corn borer (Ostrinia nubilalis) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow leaves, older first; stunted plants | Nitrogen deficiency |
Yellow, curled leaves; stunted plants. | Aphids |
Purplish patches on leaves | Phosphorus deficiency(common in cool spring soils) |
Brown leaf tips | May be a reaction to bright sun and heat (temperatures above 80° F.) |
Tan spots with dark borders | Cercospora leaf spot (Cercospora spp.) |
Meandering, white or translucent, irregular tunnels in leaves | Leafminers |
Small holes, shot-hole injury | Flea beetles (Phyllotreta spp.) |
Affecting Roots: | |
Signs or Symptoms | Cause |
Internal black, dead, hard spots | Boron deficiency |
Forked roots | Forked roots |
Small, poorly developed roots | Small, poorly developed roots |
Light color and wider zoning of rings in root | High temperature and fluctuating soil moisture |
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Affecting Leaves: | ||||
Signs or Symptoms | Cause | |||
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Birch leafminer (Fenusa pusilla) or Aphids(several, species unknown) |
Affecting Trunk and Larger Branches: | |
Signs or Symptoms | Cause |
Tunneling, raised, papery bark, or dieback | Bronze birch borer (Agrilus anxius Gory) |
Areas of dead bark With discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves curled, chewed | Boxelder leafroller (Archips negundanus) |
Leaves thickened around midrib | Gouty veingall midge (Continaria negundinis) |
New growth is small, distorted | Eriophyid mites |
Sucking on leaves, honeydew often present | Boxelder and maple aphids (Periphyllus spp.) |
Small cottony indentations on leaf underside | Eriophyid mites |
Masses of reddish eggs on leaves | Boxelder bug (Boisea trivittata) |
Affecting Trunk and Larger Branches: | |
Signs or Symptoms | Cause |
Discolored areas, dead bark containing small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Open wounds, internal decay, swollen areas in stem | Stem decay fungi (Pholiota sp., Pleurotussp., and various fungal genera) |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (Pholiota sp., Pleurotussp., and various fungal genera) |
Affecting Seeds: | |
Signs or Symptoms | Cause |
Feeding on seeds | Boxelder bug (Boisea trivittata) |
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Affecting General Plant and Roots: | |
Signs or Symptoms | Cause |
Yellow, stunted plants that wilt during bright, hot days and recover at night. | Usually a sign of root injury. Pull up plant and check for root-knot nematodes or cabbage root maggots (below) |
Irregularly shaped galls | Root-knot nematode (Meloidogyne spp.) |
Roots are riddled with slimy, winding tunnels | Cabbage root maggots |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow v-shaped spots on leaf margins with blackened veins; stems show internal black streaks | Black rot (Xanthomonas campestris) |
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting | Fusarium yellows (Fusarium oxysporum) |
Yellow leaves, older leaves first, slow growth | Nitrogen deficiency |
Older leaves whitish and drooping | Cold injury, wind injury |
Yellow, curled leaves; stunted plants | Aphids |
White to bronze spots, wilted leaves | Thrips |
White spotting, then brown, often distorted leaves that wilt and die | Harlequin bug (Margantia histrionica) |
Light-colored spots on leaves turn papery; white mildew on leaf undersides | Downy mildew (Peronospora effusa) |
Small pitted holes, shot-hole injury | Flea beetles (Phyllotreta spp.) |
Large hole in leaves; outer leaves riddled, excrement found at base of cabbage head | Imported cabbage worm (Pieris rapae),Cabbage looper, Diamondback moth(Plutella xylostella), or Grasshoppers(Melanoplus spp.) |
Leaves with meandering tunnels | Leafminer |
Affecting Inflorescences or Heads: | |
Signs or Symptoms | Cause |
Hollow stem, smaller, uneven head formation | Excess nitrogen, or potassium deficiency |
Black areas in center of head | Rot due to water collecting inside head |
Small heads that form prematurely (bolt) | High temperature stress, poorly adapted variety, or exposure of plants to fluctuating warm/cool temperatures |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Tan to dark-brown leaf margins | Heat injury |
Poor sprout development | Nitrogen or potassium deficiency; poor variety choice |
Sticky, blackened sprouts | Aphids |
Holes in leaves | Imported cabbage worm (Pieris rapae) or Cabbage looper |
Affecting Roots: | |
Signs or Symptoms | Cause |
Yellow, stunted plants that wilt during bright, hot days and recover at night. | Usually a sign of root injury. Pull up plant and check for root-knot nematodes or cabbage root maggots (below) |
Irregularly shaped galls | Root-knot nematode (Meloidogyne spp.) |
Roots are riddled with slimy, winding tunnels | Cabbage root maggots |
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Affecting Leaves and Heads: | |
Signs or Symptoms | Cause |
Yellow V-shaped spots on leaf marginsheads dwarfed and often one-sided | Black rot (Xanthomonas campestris) |
Stunted, wilted, yellow plants. Youngest plants and seedlings are affected | Root maggots |
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting | Fusarium yellows (Fusarium oxysporum) |
Purple leaves on transplants | Usually indicates a Phosphorus Deficiency |
Older leaves yellow, shrunken stems, dark near soil line; weak plants may wilt and die | Rhizoctonia (Rhizoctonia spp.) |
Black specks to larger spots on heads | Downy mildew (Peronospora effusa) |
Brown leaf tips | May be a reaction to bright sun and heat (temperatures above 80° F.) |
Split heads | Too much water |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Small holes, shothole injury | Flea beetles (Phyllotreta spp.) |
Large hole in leaves; outer leaves riddled, excrement found at base of cabbage head | Cabbage worms (Pieris rapae) or Cabbage looper |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, dwarfed young leaves, bushy growth, purpled leaves | Aster yellows (Phytoplasma) |
Yellow leaves, older first; stunted plants | Nitrogen deficiency |
Yellow-bronze, curled leaves; bushy top growth | Aphids |
Dark spots with yellow borders | Cercospora leaf blight (Cercospora spp.) if younger leaves are affected. Alternaria leaf blight (Alternaria spp.) if older leaves are affected. |
Seedlings clipped off at soil line | Cutworms (Noctuidae spp.) |
Poor seedling emergence | Crusted soil; high temperatures |
Affecting Roots: | |
Signs or Symptoms | Cause |
Roots chewed, meandering scars allon root with a rusty-red color | Carrot rust fly (Psila rosae) |
Yellow, stunted plants that wilt during bright, hot days and recover at night | Usually a sign that roots are injured. Pull up plant and check roots for Wireworms or Root-knot nematodes (see below) |
Small, irregular holes scattered over surface of root; Damage usually occurs later in the season and is worse in dry years. | Wireworms |
Bumps on roots and deformed carrots | Root-knot nematodes (Meloidogyne spp.) |
Jagged cracks, water-soaked appearance | Freezing injury |
Forked roots | Can occur if soils are heavy, compacted, or stony; if root tips are injured; if roots are overcrowded. |
Dark tunnels, often in a zig-zag pattern, on upper and outer part of root | Carrot weevil (Otiorynchus spp.) |
Internal cavity spot | Calcium deficiency |
Spindly, short roots | Can be caused by potassium deficiency or excessive heat |
Poor color and taste | Caused by magnesium deficiency,phosphorus deficiency, low temperatures and excessive heat |
Small, woody, hairy, pale roots | Carrot yellows (Phytoplasma) |
Green shoulders | Exposure to sunlight |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Roots are riddled with slimy, winding tunnels | Cabbage root maggots |
Affecting Roots: | |
Signs or Symptoms | Cause |
Yellow v-shaped spots on leaf margins with blackened veins | Black rot (Xanthomonas campestris) |
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting | Fusarium yellows (Fusarium oxysporum) |
Large hole in leaves; outer leaves riddled, excrement found at base of cabbage head | Cabbage worms (Pieris rapae) or Cabbage looper |
Small holes, shothole injury | Flea beetles (Phyllotreta spp.) |
Affecting Heads: | |
Signs or Symptoms | Cause |
Black specks or spots on heads | Downy mildew (Peronospora effusa) |
Curds turn brown and appear watersoaked | Boron deficiency or exposure of curds to bright sun and high temperatures |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, dwarfed young leaves, bushy growth, purpled leaves | Aster yellows (Phytoplasma) |
Yellow leaves, older first; stunted plants | Nitrogen deficiency |
Yellow leaves, reddish stalks | Fusarium yellows (Fusarium oxysporum) |
Yellow, curled leaves | Aphids |
Yellow, distorted new growth | Tarnished plant bug (Lygus pratensis) |
Mottled, yellow leaves, twisted stems, dwarfing | Celery mosaic |
Brown mottling of leaves, cross-wise cracks on stalks | Boron deficiency |
Discolored streaks on stalk | Potassium deficiency |
Rosetting of leaves | Phosphorus deficiency |
Blackening at center with death of growing points | Calcium deficiency |
Irregular yellow-brown leaf spots; sunken tan, elongated spots on stalks | Cercospora leaf blight (Cercospora spp.) |
Dwarfed, rotted plants | Carrot rust fly (Psila rosae) |
Chewed leaves | Several worms including carrot (or celery) worm, Armyworm (Euxoa auxiliaris) , or Cabbage loopers |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow leaves, older first; stunted plants | Nitrogen deficiency |
Yellow, curled leaves; stunted plants | Aphids |
Purplish patches on leaves | Phosphorus deficiency |
Brown leaf tips | May be a reaction to bright sun and heat (temperatures above 80° F.) |
Tan spots with dark borders | Cercospora leaf spot (Cercospora spp.) |
Yellow, rotted leaves; light-colored spots on upper leaf surface, white mildew on leaf undersides | Downy mildew (Peronospora effusa) |
Stunted, crinkled leaves | Curly top |
White or translucent, irregular tunnels in leaves | Leafminers |
Small holes, shot-hole injury | Flea beetles (Phyllotreta spp.) |
Chewed terminals and leaves | Beet armyworm (Euxoa auxiliaris) |
- Details
Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc. (Prunus spp.)
|
Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Tree decline in vigor | Phytophthora root rot (Phytophthoraspp.), Cytospora Canker (Valsa spp.,Leucostoma spp.), or Verticillium wilt(Verticillium spp.) |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed, no associated webbing | Pearslug (Caliroa derasi) |
Upper surface of the leaf skeletonized | Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer |
Webbing associated with chewing | Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum) |
Leaves with small, circular holes | Shot hole disease |
White flecking injuries | White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Leaves yellow | Iron chlorosis or X-disease |
Leaves with small, pouch or finger-like projections | Fingergall mites (Phytoptus species) |
New leaves curled | Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi) |
New leaves curled and thickened and red/purple | Peach leaf-curl disease |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Black galls on branches | Black knot of cherry (Apiosporina morbosa) |
Stem decay and/or hoof-shaped fruiting body (conk) | Decay fungus (Phellinus pomaceus) |
Scales | Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi) |
Small pinhead-sized exit holes in branches | Shothole borer (Scolytus rugulosus) |
Branches die back | Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus) |
Gumming and dark colored branches | Shothole borer (Scolytus rugulosus), or Cytospora canker (Valsa spp.,Leucostoma spp.) or Bacterial Blight (Pseudomonas syringae) |
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytopthora sp.) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Fruit tunneled | European earwig (Forficula auricularia L.) |
Fruit with sunken, corky areas | Plant bug (Lygus species), Hail injury, or Boxelder bug (Boisea trivittata) |
Puncture wounds in fruit | Bird damage (Robins, finches, etc.) |
Chokecherry fruit enlarged, hollow | Chokecherry gall midge (Contarinia virginianae) |
Maggots in cherry fruit | Western cherry fruit fly (Rhagoletis indifferens Curran |
- Details
Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc. (Malus spp.)
|
Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Tree decline in vigor | Phytophthora root rot (Phytophthoraspp.), Cytospora Canker (Valsa spp.,Leucostoma spp.), or Verticillium wilt(Verticillium spp.) |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed, no associated webbing | Pearslug (Caliroa derasi) |
Upper surface of the leaf skeletonized | Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer |
Webbing associated with chewing | Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum) |
Leaves with small, circular holes | Shot hole disease |
White flecking injuries | White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Leaves yellow | Iron chlorosis or X-disease |
Leaves with small, pouch or finger-like projections | Fingergall mites (Phytoptus species) |
New leaves curled | Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi) |
New leaves curled and thickened and red/purple | Peach leaf-curl disease |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Black galls on branches | Black knot of cherry (Apiosporina morbosa) |
Stem decay and/or hoof-shaped fruiting body (conk) | Decay fungus (Phellinus pomaceus) |
Scales | Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi) |
Small pinhead-sized exit holes in branches | Shothole borer (Scolytus rugulosus) |
Branches die back | Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus) |
Gumming and dark colored branches | Shothole borer (Scolytus rugulosus), orCytospora canker (Valsa spp.,Leucostoma spp.) orBacterial Blight (Pseudomonas syringae) |
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytopthora sp.) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Fruit tunneled | European earwig (Forficula auricularia L.) |
Fruit with sunken, corky areas | Plant bug (Lygus species), Hail injury, orBoxelder bug (Boisea trivittata) |
Puncture wounds in fruit | Bird damage (Robins, finches, etc.) |
Chokecherry fruit enlarged, hollow | Chokecherry gall midge (Contarinia virginianae) |
Maggots in cherry fruit | Western cherry fruit fly (Rhagoletis indifferens Curran |
- Details
Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc. (Prunus spp.)
|
Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Tree decline in vigor | Phytophthora root rot (Phytophthoraspp.), Cytospora Canker (Valsa spp.,Leucostoma spp.), or Verticillium wilt(Verticillium spp.) |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed, no associated webbing | Pearslug (Caliroa derasi) |
Upper surface of the leaf skeletonized | Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer |
Webbing associated with chewing | Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum) |
Leaves with small, circular holes | Shot hole disease |
White flecking injuries | White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Leaves yellow | Iron chlorosis or X-disease |
Leaves with small, pouch or finger-like projections | Fingergall mites (Phytoptus species) |
New leaves curled | Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi) |
New leaves curled and thickened and red/purple | Peach leaf-curl disease |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Black galls on branches | Black knot of cherry (Apiosporina morbosa) |
Stem decay and/or hoof-shaped fruiting body (conk) | Decay fungus (Phellinus pomaceus) |
Scales | Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi) |
Small pinhead-sized exit holes in branches | Shothole borer (Scolytus rugulosus) |
Branches die back | Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus) |
Gumming and dark colored branches | Shothole borer (Scolytus rugulosus), or Cytospora canker (Valsa spp.,Leucostoma spp.) or Bacterial Blight (Pseudomonas syringae) |
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytopthora sp.) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Fruit tunneled | European earwig (Forficula auricularia L.) |
Fruit with sunken, corky areas | Plant bug (Lygus species), Hail injury, or Boxelder bug (Boisea trivittata) |
Puncture wounds in fruit | Bird damage (Robins, finches, etc.) |
Chokecherry fruit enlarged, hollow | Chokecherry gall midge (Contarinia virginianae) |
Maggots in cherry fruit | Western cherry fruit fly (Rhagoletis indifferens Curran |
- Details
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Affecting Seed, seedling, and whole plant: | |
Signs or Symptoms | Cause |
Wilted, stunted plants and/or spotty, poor stands | May be due to several soil-dwelling pests including: Wireworm, Seed corn maggots, or, less commonly, white grubs |
Wilting, stunting, and poor germination | Corn root worms |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Numerous small holes, bleached out spots or stripes on leaves | Flea beetles(Phyllotreta spp.) |
Ragged leaf margins on young plants; plants cut at base of stem | Cutworms (Noctuidae spp.) |
Holes in leaves, shot-hole leaf injury | Corn earworm (Heliothis zea ) , European corn borer (Ostrinia nubilalis) , or Armyworm (Euxoa auxiliaris) |
Round, brown raised spots on leaves | Rust |
Mottled, stunted new leaves; poor kernel formation at base of ear | Maize dwarf mosaic virus |
White-black, puffed-out growths on ears, tassels, and stems | Smut (Ustilago maydis) |
Older leaves purple on young plants | Phosphorus deficiency |
Yellow leaves, older first; stunted plants | Nitrogen deficiency |
Yellow, curled leaves; stunted plants | Aphids |
Affecting Ears: | |
Signs or Symptoms | Cause |
Irregular ears with corky bands at the base of kernels | Boron deficiency, phosphorus deficiency, or potassium deficiency |
Large, chewed areas or dry, brown exposed kernels at the top of ear | Birds |
Hollowed-out kernels in the upper half of the ear | Sap Beetles |
Damage to developing kernels at ear tips | Corn earworm |
Bored ears and stalks, with damage seen anywhere on ear (not just at tips) | European corn borers (Ostrinia nubilalis) and/or Armyworms (Euxoa auxiliaris) |
- Details
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed | Cottonwood leaf beetle (Chrysomela scripta), Spiny elm caterpillar (Nymphalis antiopa), Fall webworm (Hyphantria cunea), or Tussock moth (Dasychira vagans) |
Webbing/Tents produced | Fall webworm (Hyphantria canea),Western tent caterpillar (Malacosoma californicum), or Forest tent caterpillar(Malacosoma disstria) |
Small holes chewed in leaves | Flea beetles (Chrysomelidae) |
Leaves tunneled | Aspen leafminer (Phyllocnistis populiella) |
Leaves spotted with young leaves blackened | Shoot blight(Venturia populina) or Frost injury |
Black spots with yellow margins | Marssonina blight (Marssonina populi) |
Black, irregular spots | Septoria leaf spot and canker (Septoria popolicole) |
Blackish-brown round spot, which drops out of leaf, leaving shothole-like appearance | Ink spot (Ciborinia whetzelii) |
Rust to orange colored spots | Conifer-aspen rust (Melampsora spp.) |
Yellowed leaves | Root damage caused by under or over watering, or Iron chlorosis |
White powdery material on upper or lower surface of leaves | Powdery mildew (Erysiphe cichoracerum) |
Leaf petioles, veins with swelling | Petiole-gall aphids (Pemphigus spp.) |
Leaves generally distorted and thickened | Poplar vagabond aphid (Mordwilkoja vagabunda) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Hollow swellings on new shoots | Petiole-gall aphids (Pemphigus spp.) |
Terminal leaves distorted into thickened mass | Poplar vagabond aphid(Mordwilkoja vagabunda) |
Twigs shredded in irregular row | Cicada oviposition injury (Platypeisidae) |
Swellings in twigs, small branches | Poplar gall borer (Superda inornata) or Hail injury (upper surface only) |
Scales on twigs, branches | Oystershell scale (Lepidosophes ulmi) |
Catkins grossly distorted and enlarged | Cottonwood catkin gall mite (Eriophyes neoessigi) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (various species) |
Open wounds, internal decay, swollen areas in stem | Stem decay fungi (various species) |
Masses of caterpillars resting on bark | Forest tent caterpillar (Malacosoma disstria) |
Tunneling in trunk, often with orange staining ooze | Cottonwood borer (Plectodera scalator),Poplar borer (Saperda calcarata),Cottonwood Crown Borer, or American hornet moth (Sesia tibialis) |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood/slime flux |
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Insects visiting oozing sap from trunk | Flies (various families) |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms: | Cause: |
White root decay with white mycelial fans between bark and wood | Armillaria root disease (Armillaria mellea) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
- Details
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Large holes chewed in leaves | Speckled green fruitworm, Redhumped caterpillar (Schizura concinna) , or Forest tent caterpillar. |
Silken tents produced | Western tent caterpillar or Fall webworm(Hyphantria cunea) |
Caterpillar living within a case | Snailcase bagworm (Apterona helix) |
Terminal leaves curled and tied together with silk | Fruittree leafroller or Obliquebanded leafroller |
Skeletonized leaves | Apple and thorn skeletonizer (Choreutis pariana) or Apple flea beetle (Phyllotretaspp.) |
"Shothole" feeding wounds in leaf, usually with sucker growth | Apple flea beetle (Phyllotreta spp.) |
Raised leafmines | Western tentiform leafminer (Phyllonorycter elmaella) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Pale green or yellow leaves | Iron chlorosis. See Nutrient Deficiencies |
Rust orange spots | Juniper rusts |
Black mold on surface of leaf | Apple scab (Venturia inaequalis) |
Rusty blisters or scabby patches on leaves | Blister mites. See Eriophyid Mites |
Bronzing of leaves | Two-spotted spidermite or McDaniel spider mite |
Curling distortions of new growth in spring | Rosy apple aphid |
Blackened and wilted leaves | Fireblight (Erwinia amylovora) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twigs shredded by a line of multiple punctures | Cicada oviposition wounds |
Blackened, wilting, and crooked tips | Fireblight (Erwinia amylovora) |
Black beetle tunneling, with small exit holes | Shothole borer |
Scales on twigs | Oystershell scale or European fruit lecnium |
Cottony insects on twigs | Woolly apple aphid or Mealbugs |
Discolored areas, dead bark containing small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Boring into trunk | Flatheaded appletree borer - (Chrysobothris mali) |
Bark beetle tunneling, small exit holes | Shothole borer |
Cottony insects on trunk and/or roots | Woolly apple aphid |
Internal decay and/or shelf-like fruiting structures (conks) | Decay fungus |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytophthoraspp.) |
Galls at ground line | Crown gall |
Affecting Roots: | |
Signs or Symptoms | Cause |
White root decay and white mycelial fans between bark and wood | Armillaria root disease (Armillaria spp.) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Tunneling in fruit | Codling moth (Cydia pomonella) |
Scarring or scabbing of fruit | Fruittree leafroller, Hail injury, or Apple scab (Venturia inaequalis) |
Pitted, scarred fruit | Tarnished Plant Bug (Lygus lineolaris) |
- Details
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Affecting Leaves and Vines: | |
Signs or Symptoms | Cause |
Plants wilt, foliage looks burned; preceded by pale green areas forming on leaves | Squash bug (Anasa tristus) |
Sudden wilting of a runner or part of a runner | Squash vine borer (Melitta satyriniformis) |
Leaves wilt, yellow, and curl | High Aphid populations |
Vines wilt and die gradually, starting with newer leaves; no leaf yellowing is present | Bacterial wilt (Erwinia tracheiphila) |
Small, pitted leaf holes on young plants | Cucumber beetles (Acalymma vittata) |
Distorted, Yellow spots on leaves with mottling and wrinkling of older leaves | Mosaic viruses |
Older leaves mottled yellow between veins | Downy mildew (Peronospora effusa) |
Powdery, white spots on upper surface of leaves especially | Powdery mildew |
Leaf spots that begin as water-soaked, then turn gray, die and drop out leaving foliage with a shot-hole appearance | Angular leafspot (Pseudomonas syringae) |
If water-soaked, yellow spots turn brown | Anthracnose |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Small, brown, angular fruit spots | Angular leafspot (Pseudomonas syringae) |
Brown and sunken zoned spots | Alternaria (Alternaria spp.) |
Circular, black, sunken cankers | Anthracnose |
Misshapen, yellow mottled fruit, often with a bitter taste | Mosaic virus |
Fruit wilts and shrivels | Bacterial wilt (Erwinia tracheiphila) |
Fruit is narrow at stem end | Potassium deficiency |
Fruit has a dull bronze color | Phosphorus deficiency |
Fruit is light colored | Nitrogen deficiency |
Dark pitting of fruit | Cold damage |
- Details
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Affecting Leaves: | |
Signs or Symptoms | Cause |
White flecks in leaves | Rose leafhoppers (Edwardsiana rosae) orTwospotted spider mite |
White powdery material on upper or lower surface of leaf | Powdery mildew (Mycosphaerella sp.) |
Leaves puckered, often thickened and discolored | Currant aphid (Amphorophora agathonica Hottes or Cryptomyzus ribis) |
Leaves chewed | Imported currantworm (Nematus ribesi) or Western tent caterpillar (Malacosoma californicum) |
Hollow swelling in leaves | Gall-making sawfly |
Orange to yellow colored spots on underside of leaf | Leaf rusts (various species) |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Tunneling in stems or branches | Current borer (Synanthedon tipuliformis) or Bronze cane borer (Agrilus aurichaleceus) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Maggot in fruit | Currant fruit fly (Epochra canadensis) |
- Details
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed | Redhumped caterpillar (Schizura concinna) |
New leaves curled | Sunflower aphid (Aphis helianthi) |
Black spots on leaves | Septoria leaf spot and canker (Septoria cornicola) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Scales | Oystershell scale (Lepidosaphes ulmi) |
Dead areas on stem | Nectria canker (Nectria sp.) or Root collar rot (Phytophthora sp.) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Feeding in or on berries | Conifer seed bugs (Leptoglossus occidentalis) |
- Details
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Affecting Buds: | |
Signs or Symptoms | Cause |
Buds tunneled | Western spruce budworm (Choristoneura occidentalis) |
Affecting Needles: | |
Signs or Symptoms | Cause |
Newer needles being chewed | Douglas-fir tussock moth (Orgyia pseudotsugata) or Western spruce budworm (Choristoneura occidentalis) |
Needles with discolored spotting, various color spots | Needle casts (various fungi) |
Needles with discolored spotting, rust or orange color spots | Conifer aspen rust (Melampsora spp.) |
Needles to exterior of tree bleached or brown, developing late winter | Winter dessication |
Brown felt-like materials on needles or branches (high elevations) | Brown felt blight (Herpotricha juniperi) |
Needles bent, twisted | Cooley spruce gall adelgid (Adelges cooleyi) or Frost injury |
Woolly aphids on needles | Cooley spruce gall adelgid (Adelges cooleyi) |
Whole tree fades, reddens | Douglas-fir beetle (Dendroctonus pseudotsugae) |
Affecting Cones: | |
Signs or Symptoms | Cause |
Flowers tunneled | Western spruce budworm (Choristoneura occidentalis) |
Woolly aphids on cones | Cooley spruce gall adelgid (Adelges cooleyi) |
Sucking on developing cones | Conifer seed bugs (Leptoglossus occidentalis) |
Affecting Trunk or Larger Branches: | |
Signs or Symptoms | Cause |
Witches’ brooms on branches, small shoots emerging from branch | Dwarf mistletoe |
Large galls | Bacteria-like gall or Burl |
Aphids | Giant conifer aphids (Cinara spp.) |
Tunneling in trunk, branches | Douglas-fir beetle (Dendroctonus pseudotsugae) |
Open wounds, internal decay, swollen areas in stem | Stem decay fungi (Fomitopsis pincola,Cryptoporus volvatus and various fungal genera) |
Affecting Roots: | |
Signs or Symptoms | Cause |
White root decay with white mycelial fans between bark and wood | Armillaria root disease (Armillaria mellea) |
- Details
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Large holes in leaves, skeletonized leaves; plants and leaflets stripped | Colorado potato beetle (Leptinotarsa decemlineata) |
Tiny, pitted holes in leaves, leaves may have a lacelike appearance and turn dull, dry green | Flea beetle (Phyllotreta spp.) |
Yellow leaves turn brown and die | Lacebug |
Yellow leaves accompanied by gradual wilting and browning between leaf veins | Verticillium wilt (Verticillium spp.) |
Yellow mottling of leaves; curling and malformation of leaves | Tobacco mosaic virus or cucumber mosaic virus |
Circular, dark spots on leaves | Alternaria Leaf Blight |
Large holes in leaves | Grasshoppers (Melanoplus spp.) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Dry, brown chew marks | Colorado potato beetle (Leptinotarsa decemlineata) |
- Details
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves skeletonized, primarily on leaf underside | Elm leaf beetle (larvae) (Xanthogaleruca luteola) |
Holes chewed through leaves | Elm leaf beetle (Xanthogaleruca luteola) |
Leaves irregularly chewed | Spiny elm caterpillar (Nymphalis antiopa);Fruittree leafroller (Archips argyrospila),Forest tent caterpillar (Malacosoma disstria), or Fall webworm (Hyphantria cunea) |
Masses of dark, spiny caterpillars on leaves | Spiny Elm Caterpillar - Morning Cloak Butterfly (Nymphalis antiopa) - No significant damage. |
New leaves small, twisted | Eriophyid mites (Eriophyidae) or Phenoxy herbicide injury. See Chemical Injury |
Leaves curled, thickened | Woolly aphids (Eriosoma spp.) |
Leaves with white flecks | Leafhoppers (Erythroneura spp.) |
Pale green or yellow leaves | Iron chlorosis |
Sucking insects on leaves, often with associated honeydew | European elm scale (Gossyparia spurai) or Elm leaf aphid (Myzocallis ulmifolii) |
Yellowing, wilting foliage | Scale "flagging" - European elm scale, Dutch elm disease (Ophiostoma ulmi), or Verticillium wilt (Verticillium spp.) |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Scales | European fruit lecanium(Parthenolecanium corni) or European elm scale (Gossyparia spuria) |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Borers | Elm borer (Saperda tridentata Oliver) or Flatheaded appletree borer(Chrysobothris femorata) |
Areas of dead bark With discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Open wounds, internal decay, or swollen areas on stem | Stem decay fungi (Collybia velutipes,Phellinus igniarius and various genera) |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (Collybia velutipes, Phellinus igniarius and various genera) |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood / slime flux |
- Details
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Notches cut in edge of leaves | Black vine weevil (Otiorhynchus sulcatus) |
Leaves mined, edges curled with webbing | Lilac leafminer (Caloptilia syringella) |
New leaves curled, thickened | Bean aphids (Aphis fabae) |
Flecking, discoloration | Twospotted spider mite (Tetranychus urticae Koch) |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms | Cause |
Chewing of roots | Black vine weevil (Otiorhynehus sulcatus) |
- Details
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Affecting Buds: | |
Signs or Symptoms | Cause |
Buds tunneled | Western Spruce budworm (Choristoneura occidentalis) |
Affecting Needles: | |
Signs or Symptoms | Cause |
New needles being chewed | Douglas-fir tussock moth (Orgyia pseudotsugata) or Western spruce budworm (Choristoneura occidentalis) |
Needles to exterior of tree bleached or brown, developing late winter | Winter dessication |
Various colored spots | Needlecast diseases |
Orange colored pustules on needles | Fir broom rust (Melampsorella caryophyllacearum) |
Brown felt-like material on needles, branches | Brown felt blight (Herpotrichia juniperi) |
Needles being mined | White fir needleminer (Epinotia meritana) |
Aphids on needles | Giant conifer aphids (Cinara spp.) |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Large aphids on branches, twigs | Giant conifer aphids (Cinara spp.) |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Bark beetles | Fir engraver (Scolytus ventralis Le Conte) |
Borers | Flatheaded fir borer (Melanophila drummondi) |
Witches brooms on branches, orange to yellow colored pustules on needles | Fir broom rust (Melampsorella caryophyllacearum) |
Large aphids on branches or trunk | Giant conifer aphids (Cinara spp.) |
Fungal fruiting bodies (mushroom, conks) present | Stem decay fungi (various species) |
Open wounds, internal decay, swollen areas in stem | Stem decay fungi (various species) |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms | Cause |
White root decay with white mycelial fans between bark and wood | Armillaria root disease (Armillaria mellea) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
White flecks in leaves | Rose leafhoppers (Edwardsiana rosae) orTwospotted spider mite |
White powdery material on upper or lower surface of leaf | Powdery mildew (Mycosphaerella sp.) |
Leaves puckered, often thickened and discolored | Currant aphid (Amphorophora agathonica Hottes or Cryptomyzus ribis) |
Leaves chewed | Imported currantworm (Nematus ribesi) or Western tent caterpillar (Malacosoma californicum) |
Hollow swelling in leaves | Gall-making sawfly |
Orange to yellow colored spots on underside of leaf | Leaf rusts (various species) |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Tunneling in stems or branches | Current borer (Synanthedon tipuliformis) or Bronze cane borer (Agrilus aurichaleceus) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Maggot in fruit | Currant fruit fly (Epochra canadensis) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves being chewed | Fruittree leafroller (Archips argyrospila) or Spiny elm caterpillar, usually in masses (Nymphalis antiopa) |
Leaves with white flecking (net-leaf hackberry) | Lacebugs (Corythucha spp.) |
Leaves yellowed | Iron chlorosis or other deficiency, or Root damage from under or over watering |
Leaves with large, conspicuous raised areas | Hackberry nipplegall maker (Pachypsylla celtidismamma) |
Leaves with small raised areas | Hackberry blistergall maker (Pachypsylla celtidivescula Riley) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Cellophane-like webbing in late summer | Spider mites (Tetranychidae spp.) |
Twigs deformed into dense witches’ broom | Eriophyid mites / Powdery mildew complex |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Borers / Bark beetles | Flatheaded appletree borer(Chrysobothris femorata) |
Clear to white oozing or frothy maladorous liquid exiting from wounds | Bacterial wetwood / Slime flux |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Blackened and wilting leaves | Fireblight (Erwinia amylovora) |
Pale green or yellow leaves | Iron chlorosis |
Caterpillars associated with webbing | Fall webworm (Hyphantria canea) or Western tent caterpillar (Malacosoma californicum) |
Chewing leaves | Pearslug (Caliroa cerasi) or Forest tent caterpillar (Malacosoma disstria) |
Leaves curled in spring | Apple aphid (Aphis pomi) |
Reddish spotting on upper surface/orange pustules, spiny eruption on underside | Cedar-Apple Rust (Gymnosporangium rusts) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Blackened, wilting, and crooked tips | Fireblight (Erwinia amylovora) |
White, wax-covered insects | Mealybug (Pseudococcidae) or Wooly hawthorn aphid (Eriosoma crateagi) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood and slime flux |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Caterpillars chewing on leaves | Fruittree leafroller (Archips argyrospila) |
Leaflets distorted into thickened pods | Honeylocust podgall midge (Dasineura gleditschiae) |
Honeydew appearing on leaves | Cottony maple scale (nymph stage on leaves) - (Pulvinaria innumerabilis) |
Leaves turn bronze, may prematurely drop | Honeylocust spider mite(Platytetranychus multidigituli) or Honeylocust rust mite (Aculops spp.) |
Yellowed leaves | Root damage cased by under or over watering |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Tips of twigs thickened, may have dieback | Honeylocust podgall midge (severe injury killing growing points) |
Scales | Cottony maple scale (Pulvinaria innumerabilis) |
Twigs with small splintering wounds | Putnam's cicada [egg laying wounds] - (Platypedia putnami) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Areas of dead bark (cankers) or Discoloration and small pimple-like fruiting bodies (pycnidia) in the bark | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Amber colored gummy exudate (gummosis) | Stress response from drought, sunscald, collar rot, cankers or other causes |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves curled and with blackened margins | Honeysuckle blight |
Leaves tightly curled, associated bunchy growth | Honeysuckle witches' broom aphid (Hyadaphis tartaricae) |
Early season leaves curled, yellow | Aphids |
White powdery material on upper or lower surface of leaf | Powdery mildew |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellowing leaves | Nitrogen deficiency or natural senescence. |
Yellow leaves | Aphids |
Spots on leaves | Iris Leaf Spot |
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Affecting Needles: | |
Signs or Symptoms | Cause |
Frothy masses on needles | Juniper spittlebug (Clastoptera juniperinaBell). |
Honeydew present | Giant conifer aphids (Cinara spp.) |
Needles chewed and fragments tied with webbing | Juniper webworm (Dichomeris marginella) |
Aphids on needles | Giant conifer aphids (Cinara spp.) |
Pale green or yellow needles | Iron chlorosis |
Needles tips bleached or brown | Winter dessication or Vole injury |
Needles become grayish, with small flecks | Spruce spider mite (Oligonychus ununguis) |
Scales on needles | Juniper scale (Carulaspis juniperi Bouche) or Fletcher scale (Parthenolecanium fletcheri) |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Twig galls | Juniper rusts (Gymnosporangium spp.) |
Twig dieback | Grasshoppers (Melanoplus spp.)Phytophthera Root or Crown Rot |
Large aphids on branches, twigs | Giant conifer aphids (Cinara spp.) |
Brown felt-like material on needles and branches (higher elevations only) | Brown felt blight (Herpotricha juniperi) |
Affecting Trunk or Larger Branches: | |
Signs or Symptoms | Cause |
Witches' brooms or branch galls | Juniper broom rust (Gymnosporangium speciosum) |
Large aphids on branches, trunk | Giant conifer aphids (Cinara spp.) |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms | Cause |
White root decay with white mycelial fans between bark and wood | Armillaria root disease (Armillaria mellea) |
Brown, discolored roots | Phytophthera Root or Crown Rot |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow v-shaped spots on leaf margins | Black rot (Xanthomonas campestris) |
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems, usually occurs soon after transplanting | Fusarium yellows (Fusarium oxysporum) |
Yellow leaves, older leaves first, slow growth | Nitrogen deficiency |
Yellow leaves | Cold weather |
Yellow, curled leaves; stunted plants | Aphids |
Brown leaves that wilt and die | Harlequin bug (Margantia histrionica) |
Tan to dark-brown leaf margins | Heat injury |
Small holes, shothole injury | Flea beetles (Phyllotreta spp.) |
Large holes in leaves; outer leaves riddled | Cabbage worms (Pieris rapae) or Cabbage looper |
Affecting Roots: | |
Yellow, stunted plants that wilt during bright, hot days and recover at night | Cabbage root maggots |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow v-shaped spots on leaf margins | Black rot (Xanthomonas campestris) |
Yellow leaves, older leaves first, slow growth | Nitrogen deficiency |
Tan to dark-brown leaf margins | Heat injury |
Small, pitted holes in leaves | Flea beetles (Phyllotreta spp.) |
Large holes in leaves | Cabbage worms (Pieris rapae) |
Affecting Roots: | |
Yellow, stunted plants that wilt during bright, hot days and recover at night | Check roots for the following: slimy, winding tunnels mean Cabbage root maggots |
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Affecting Leaves and Heads: | |
Signs or Symptoms | Cause |
Bleached center leaves are dwarfed, curled or twisted | Aster yellows (Phytoplasma) |
Yellow or pale leaves, stunted plants | Leaf hoppers |
Yellow, distorted new growth | Tarnished plant bug (Lygus pratensis) |
Yellow leaves, slow growth, bitter taste | Nitrogen deficiency |
Yellow, curled leaves | Aphids |
Light green or yellow crinkled leaves with enlarged veins | Big vein: caused by a virus-like organism |
Dull gray-green to brown leaves | Thrips |
Mottled, ruffled leaves; stunted plants | Mosaic viruses |
Leaf margins turn brown and die | Tipburn, prevalent in hot weather |
Browning and dwarfing of plant; Velvety, white growth on leaves | Downy Mildew |
Powdery dust on upper leaf surfaces | Powdery mildew |
Outer leaf margins tan, blistering of leaves | Freezing injury |
Wilting, sudden collapse of outer leaves on mature plants | Sclerotinia drop |
Lower leaves and midribs rot near the base of the plant first | Bottom rot or Rhizoctonia (Rhizoctoniaspp.) |
Slimy, rotted heads | Gray Mold (Botrytis cinerea) |
Midrib discolored | High temperatures (> 80° F.) |
Lettuce malformed | Boron or phosphorus deficiency |
Brown center and rosetting | Calcium deficiency |
Small holes in leaves, shot-hole injury | Flea beetles (Phyllotreta spp.) |
Large hole in leaves; excrement found at base of head | Cabbage looper, Imported cabbage worm(Pieris rapae) , Beet armyworm, and Corn earworms (Heliothis zea) |
Large holes in leaves with slimy trails | Slugs and snails |
White or translucent, irregular tunnels in leaves | Leafminers |
Affecting Whole Plant: | |
Seed doesn't germinate | High soil and/or air temperatures |
Seedlings clipped off at soil line | Cutworms (Noctuidae spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Edge of leaves cut in semicircle | Leafcutter bees (Megachile spp.) |
Edge of leaves notched | Black vine weevil (Otiorhynchus sulcatus) |
Leaves with blotchy mines | Lilac leafminer (Caloptilia syringella) |
Leaves blacken and wilted | Bacterial brown spot (Pseudomonas syringaepv. syringae) |
White powdery material on upper or lower surface of leaf | Powdery mildew (Microsphaera penicillata) |
Leaves turn a rusty color | Rust Mites (eriophyid) |
Affecting Twigs and Smaller Branches: | |
Scales | Oystershell scale (Lepidosaphes ulmi) |
Borers | Lilac/ash borer (Podosesia syringae) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves being chewed | Fruittree leafroller (Archips argyrospila) or Speckled green fruitworm (Orthosia hibisci) |
Small pouch galls form on leaf surface | Linden fingergall mite (Eriophyid mite) |
Velvety patches on underside of leaves (littleleaf linden) | Linden fingergall mite (Eriophyid mite) |
Pale green or yellow leaves | Iron chlorosis |
Leaves strongly cupped | Herbicide injury. See Abiotic Injury. |
Aphids | Linden aphid (Myzocallis tiliae) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Large cottony insect develops in late spring | Cottony maple scale (Pulvinaria innumerabilis) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed | Fruittree leafroller (Archips argyrospila) |
White flecks on leaves | Leafhopper (Erythroneura spp.) |
Black to brown spots on leaves | Anthracnose (Kabatiella sp.) or Septoria leaf spot and canker (Septoria sp.) or Tar spot (Rhytisma sp.) |
Patches of reddish hairs (Rocky Mountain maple) | Eriophyid mites |
Sucking insects on leaves, often honeydew | Boxelder and maple aphids (Periphyllusspp.) or Cottony maple scale (nymphs) (Pulvinaria innumerabilis) |
Leaves yellowed (particularly silver maple) | Iron chlorosis |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twigs with row of irregularly shredded punctures | Cicada injury (Platypedia putnami) |
Large cottony insect on twigs | Cottony maple scale (Pulvinaria innumerabilis) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood and slime flux |
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) in the bark | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Large dead and discolored areas on southwest side of trunk | Winter sunscald |
Borers | Flatheaded appletree borer(Chrysobothris femorata) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, raised pouches | Eriophyid mites |
Orange spots | Juniper rusts (Gymnosporangium spp.) |
Rusty scabs on leaf | Blister mite. See Eriophyid mites.(Phytoptus spp.) |
Chewing leaves | Pearslug (Caliroa cerasi) |
Aphids | Apple aphid (Aphis pomi) |
Blackened and wilting leaves | Fireblight (Erwinia amylovora) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Aphids | Wooly aphids (Eriosoma sp.) |
Scales | Oystershell scale (Lepidosaphes ulmi) or Mealybug (Phenacoccus spp.) |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Blackened, wilting, and crooked tips | Fireblight (Erwinia amylovora) |
Discolored areas and dead bark containing small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Luecostoma spp.) |
Large dead and discolored areas on southwest side of trunk | Winter sunscald |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood and slime flux |
Borers | Flaheaded appletree borer (Chrysobothris femorata) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves tied together with silk, chewed | Oak leafroller (Archips semiferana) |
Black/brown spotting on leaves | Anthracnose (Apiognomonia quercina) |
Frothy mass on leaf vein | Spittlebugs (Clastoptera spp.) |
Insects sucking on leaves | Spider mites (Oligonychus platani) |
Small balls on leaves | Gall wasps (Cynipidae spp.) |
Cottony growth on leaves, near midrib | Gall wasps (Cynipidae spp.) |
Pale green or yellow leaves | Iron chlorosis |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twigs shredded by multiple punctures | Cicada oviposition injury (Platypedia putnami) |
Witches' brooms on Gambel oak | Oak witches' broom (Articularia quercina) |
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) in the bark | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood / slime flux |
Stem decay and/or hoof-shaped fruiting bodies (conks) on Gambel oak | White trunk rot of oak (Phellinus everhartii) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Grubs feeding in acorn | Acorn weevils (Carculio spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow leaves, slow growth | Nitrogen deficiency |
Yellow leaves, dwarfed plants | Aphids |
Brown leaf tips; white blotches on leaves | Onion thrips |
Tips of leaves die, pale green to brown leaf spots; later leaves are black with a purple, furry mold | Downy mildew (Peronospora effusa) |
Leaf tips turn brown and die | Hot, dry weather and/or excessive heat |
Pale, green-silvery leaf spots | Can be a reaction to excessive rain or hail |
Papery, white leaf spots with a characteristic lengthwise split; brown leaf tips | Botrytis leaf blight |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Seedlings develop weak, water-soaked stems and fall over | Damping-off |
Wilted, yellow plants | Wireworm |
Yellow, wilting plants | Fusarium yellows (Fusarium oxysporum) |
Yellow, dying plants | Onion or seedcorn maggot |
Affecting Bulbs: | |
Signs or Symptoms | Cause |
Gray, water-soaked appearance of outer bulb scales | Caused by high (> 85° F.) temperatures |
Bleached, soft bulbs | Sunscald |
Water-soaked, soft bulbs | Freezing injury |
Roots turn pinkish, shrivel and die | Pink root |
Sunken, dry, brown-black areas around neck, rotted neck; gray mold on bulb surface | Neck rot |
Dark-green or black spots with concentric rings on bulb and neck | Onion smudge |
Rotted bulb | Purple blotch or white rot |
Poor bulb formation, small size | Potassium or nitrogen deficiency, late planting, or Onion thrips |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, dwarfed young leaves, bushy growth | Carrot yellows |
Yellow leaves, older first; stunted plants. | Nitrogen deficiency |
Yellow, curled leaves | Aphids |
Dark spots with yellow borders | Cercospora leaf blight (Cercospora spp.) if younger leaves are affected. Alternaria leaf blight (Alternaria spp.)if older leaves are affected. |
Affecting Roots: | |
Signs or Symptoms | Cause |
Yellow, stunted plants that wilt during bright, hot days and recover at night | Root injury. Check for Wireworms or Root-knot nematodes (Meloidogyne spp.) |
Dark tunnels, often in a zig-zag pattern, on upper and outer part of root | Carrot weevil (Otiorynchus spp.) |
Dark cankers on roots, root deterioration | Brown canker |
Rotted roots | Crop rotation needed or soil worked when wet |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, curling leaf margins, wilted plants; flowers and pods drop | Potato leaf hoppers |
Yellow, distorted new growth | Tarnished plant bug (Lygus pratensis) |
Yellow leaves, slow growth | Nitrogen deficiency |
Yellow, withered, thickened and curled leaves; flowers may drop | Pea aphids |
Yellow crinkled, mottled, curled leaves | Mosaic virus |
Mottled, yellow, crumpled leaves; rosetting | Pea enation virus |
Yellow leaves, stems yellow inside; dwarfing and wilting | Fusarium wilt (Fusarium oxysporum) |
Velvety, white growth on leaves | Downy Mildew (Peronospora effusa) |
Powdery, white leaf spots | Powdery mildew |
White stippled leaves which later become bronzed | Mites |
White or translucent, irregular tunnels in leaves | Leafminers |
Leaf holes on young plants | Striped and spotted Cucumber beetles(Acalymma vittata) |
Large holes in leaves | Army Cutworms (Euxoa auxiliaris) |
Affecting Seed, Seedling, Root: | |
Signs or Symptoms | Cause |
Seedlings clipped off at soil line | Cutworms (Noctuidae spp.) |
Stems rot near soil line and plant collapses; seeds do not germinate | Damping off |
Poor germination, damaged seedling stem; deformed, spindly seedlings | Seed corn maggots |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Blossoms drop | Excessive heat or rain |
Blossoms drop or pods fail to develop | Copper and/or molybdenum deficiency |
Brown spot or cavity on seeds | Manganese deficiency |
White, powdery spots on pods | Powdery mildew |
Holes in blossoms, tunnels in seeds | Pea weevil adults |
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Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc. (Prunus spp.)
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Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Tree decline in vigor | Phytophthora root rot (Phytophthoraspp.), Cytospora Canker (Valsa spp.,Leucostoma spp.), or Verticillium wilt(Verticillium spp.) |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed, no associated webbing | Pearslug (Caliroa derasi) |
Upper surface of the leaf skeletonized | Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer |
Webbing associated with chewing | Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum) |
Leaves with small, circular holes | Shot hole disease |
White flecking injuries | White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Leaves yellow | Iron chlorosis or X-disease |
Leaves with small, pouch or finger-like projections | Fingergall mites (Phytoptus species) |
New leaves curled | Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi) |
New leaves curled and thickened and red/purple | Peach leaf-curl disease |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Black galls on branches | Black knot of cherry (Apiosporina morbosa) |
Stem decay and/or hoof-shaped fruiting body (conk) | Decay fungus (Phellinus pomaceus) |
Scales | Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi) |
Small pinhead-sized exit holes in branches | Shothole borer (Scolytus rugulosus) |
Branches die back | Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus) |
Gumming and dark colored branches | Shothole borer (Scolytus rugulosus), or Cytospora canker (Valsa spp.,Leucostoma spp.) or Bacterial Blight (Pseudomonas syringae) |
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytopthora sp.) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Fruit tunneled | European earwig (Forficula auricularia L.) |
Fruit with sunken, corky areas | Plant bug (Lygus species), Hail injury, or Boxelder bug (Boisea trivittata) |
Puncture wounds in fruit | Bird damage (Robins, finches, etc.) |
Chokecherry fruit enlarged, hollow | Chokecherry gall midge (Contarinia virginianae) |
Maggots in cherry fruit | Western cherry fruit fly (Rhagoletis indifferens Curran |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Large holes chewed in leaves | Redhumped caterpillar (Schizura concinna) , or Forest tent caterpillar(Malacosma disstria ) |
Silken tents produced | Western tent caterpillar or Fall webworm(Hyphantria cunea) |
Caterpillar living within a case | Snailcase bagworm (Apterona helix ) |
Terminal leaves curled and tied together with silk | Fruittree leafroller or Obliquebanded leafroller |
Skeletonized leaves | Apple and thorn skeletonizer (Choreutis pariana) or Apple flea beetle (Phyllotretaspp.) |
"Shothole" feeding wounds in leaf, usually with sucker growth | Apple flea beetle (Phyllotreta spp.) |
Raised leafmines | Western tentiform leafminer |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Pale green or yellow leaves | Iron chlorosis |
Rust orange spots | Juniper rusts |
Black mold on surface of leaf | Apple scab (Venturia inaequalis) |
Rusty blisters or scabby patches on leaves | Blister mites. See Eriophyid mites. |
Bronzing of leaves | Two-spotted spidermite or McDaniel spider mite |
Curling distortions of new growth in spring | Rosy apple aphid |
Blackened and wilted leaves | Fireblight (Erwinia amylovora) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twigs shredded by a line of multiple punctures | Cicada oviposition wounds |
Blackened, wilting, and crooked tips | Fireblight (Erwinia amylovora) |
Black beetle tunneling, with small exit holes | Shothole borer |
Scales on twigs | Oystershell scale or European fruit lecanium |
Cottony insects on twigs | Woolly apple aphid or Mealybugs |
Discolored areas, dead bark containing small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Boring into trunk | Flatheaded appletree borer(Chrysobothris mali) |
Bark beetle tunneling, small exit holes | Shothole borer |
Cottony insects on trunk and/or roots | Woolly apple aphid |
Internal decay and/or shelf-like fruiting structures (conks) | Decay fungus |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytophthoraspp.) |
Galls at ground line | Crown gall |
Affecting Roots: | |
Signs or Symptoms | Cause |
White root decay and white mycelial fans between bark and wood | Armillaria root disease (Armillaria spp.) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Tunneling in fruit | Codling moth (Cydia pomonella) |
Scaring or sabbing of fruit | Fruittree leafroller, hail injury, or Apple scab (Venturia inaequalis) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Small, yellow-green spots, turning brown with lighter centers; near leaf margins first | Bacterial spot (Xanthomonas campestris) |
Mottled, yellow, curled, thick and leathery leaves | Mosaic virus |
Yellow leaves wilt and curl; shiny and sticky leaves | Aphids |
Small holes chewed in leaves | Flea beetles (Phyllotreta spp.) |
Circular, dark spots on leaves | Alternaria Leaf Blight |
New growth small, discolored, or deformed | Curly Top |
Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Young plants topple over; weak stem at soil line | Damping off |
Yellow leaves, gradual wilting | Verticillium wilt (Verticillium spp.) |
Yellowing and drooping of shoots and leaves at base of plant first. Cross section of infected stem has reddish-brown vascular system. Occurs when temperature is 80-90° F. | Fusarium wilt (Fusarium oxysporum) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Plants have blossoms, but no peppers | Extreme heat or cold |
Fruit blossoms drop prematurely; fruit is misshapen and discolored | Low temperature during blossoming and/or uneven growing conditions |
White or tan-colored, sunken, spots near tips of fruit; most often on earliest fruit during dry periods; up to 1/3 of the fruit may become dark and shriveled | Blossom end rot |
Sunken, white papery-looking areas on side of fruit exposed to the sun | Sunscald |
Small, dark brown, wartlike spots on fruit; most prevalent during damp weather | Bacterial spot (Xanthomonas campestris) |
Large, yellow to dark brown spots on ripe peppers, followed by rotting; spots have black-specked centers | Anthracnose |
Feeding at seed core with hole near stem end of pepper; sawdusty excrement is usually visible at stem end; peppers often rot and color early | European corn borer (Ostrinia nubilalis) |
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Affecting Needles: | |
Signs or Symptoms | Cause |
Mottled yellowing of needles on a branch | Winter exposure injury |
Needles to exterior of tree bleached or brown, developing late winter | Winter dessication |
Discoloration, needle drop of current or previous year's growth | Needle casts (Bifusella sp.,Davisomycella sp., Elytoderma deormans, Lophodermella sp.,Lophoedermium sp.); or Giant conifer aphids (Cinara spp.) |
Brown felt-like material on needles (high elevations) | Brown felt blight (Neopeckia coulteri) |
Needles twisted, stunted | Eriophyid mites (Trisecatus spp.) |
Aphids on needles | Giant conifer aphids (Cinnara spp.) |
Scales on needles | Pine needle scale (Chionaspis pinifoliae) |
Whole tree fades, reddens | Mountain pine beetle (Dendroctonus ponderosae Hopkins) |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Galls on small branches that turn bright orange/yellow in spring | Western gall rust (Endocronartium harknessii) |
Swollen and/or twisted terminal growth | Herbicide injury. See Chemical Injury. |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Tunnels oozing popcorn-like white pitch, often near crotches | Pine moth (Dioryctria spp.) |
Galls on large branches or trunk | Western gall rust (Endocronartium harknessii) |
Cankers, with resin and squirrel chewing | Comandra rust [in lodgepole pine] - (Cronartium comandrae) |
Roughened bark and resin production | White pine blister rust (on five needle pines) |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (various species) |
Open wounds, internal decay, swollen areas in stem | Stem decay fungi (various species) |
Regular row of holes | Woodpeckers |
Bark beetles | Engraver beetles (Ips spp.), Mountain pine beetles (Dendroctonus ponderosae), or Red turpentine beetle (Dendroctonus valens LeConte) |
Small shoots emerging from the branch |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms | Cause |
White root decay with white mycelial fans between bark and wood | Armillaria root disease (Armillaria mellea) |
Affecting Cones: | |
Signs or Symptoms | Cause |
Cones tunneled by caterpillars | Coneworms (Dioryctria spp.) |
Sucking on developing cones. | Conifer Seed Bugs |
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Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc. (Prunus spp.)
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Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Tree decline in vigor | Phytophthora root rot (Phytophthoraspp.), Cytospora Canker (Valsa spp.,Leucostoma spp.), or Verticillium wilt(Verticillium spp.) |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed, no associated webbing | Pearslug (Caliroa derasi) |
Upper surface of the leaf skeletonized | Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer |
Webbing associated with chewing | Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum) |
Leaves with small, circular holes | Shot hole disease |
White flecking injuries | White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Leaves yellow | Iron chlorosis or X-disease |
Leaves with small, pouch or finger-like projections | Fingergall mites (Phytoptus species) |
New leaves curled | Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi) |
New leaves curled and thickened and red/purple | Peach leaf-curl disease |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Black galls on branches | Black knot of cherry (Apiosporina morbosa) |
Stem decay and/or hoof-shaped fruiting body (conk) | Decay fungus (Phellinus pomaceus) |
Scales | Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi) |
Small pinhead-sized exit holes in branches | Shothole borer (Scolytus rugulosus) |
Branches die back | Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus) |
Gumming and dark colored branches | Shothole borer (Scolytus rugulosus), orCytospora canker (Valsa spp.,Leucostoma spp.) or Bacterial Blight (Pseudomonas syringae) |
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytopthora sp.) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Fruit tunneled | European earwig (Forficula auricularia L.) |
Fruit with sunken, corky areas | Plant bug (Lygus species), Hail injury, or Boxelder bug (Boisea trivittata) |
Puncture wounds in fruit | Bird damage (Robins, finches, etc.) |
Chokecherry fruit enlarged, hollow | Chokecherry gall midge (Contarinia virginianae) |
Maggots in cherry fruit | Western cherry fruit fly (Rhagoletis indifferens Curran |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed | Cottonwood leaf beetle (Chrysomela scripta), Spiny elm caterpillar (Nymphalis antiopa), Fall webworm (Hyphantria cunea), or Tussock moth (Dasychira vagans) |
Webbing/Tents produced | Fall webworm (Hyphantria canea),Western tent caterpillar (Malacosoma californicum), or Forest tent caterpillar(Malacosoma disstria) |
Small holes chewed in leaves | Flea beetles (Chrysomelidae) |
Leaves tunneled | Aspen leafminer (Phyllocnistis populiella) |
Leaves spotted with young leaves blackened | Shoot blight (Venturia populina) or Frost injury |
Black spots with yellow margins | Marssonina blight (Marssonina populi) |
Black, irregular spots | Septoria leaf spot and canker (Septoria popolicole) |
Blackish-brown round spot, which drops out of leaf, leaving shothole-like appearance | Ink spot (Ciborinia whetzelii) |
Rust to orange colored spots | Conifer-aspen rust (Melampsora spp.) |
Yellowed leaves | Root damage caused by under or over watering, or Iron chlorosis |
White powdery material on upper or lower surface of leaves | Powdery mildew (Erysiphe cichoracerum) |
Leaf petioles, veins with swelling | Petiole-gall aphids (Pemphigus spp.) |
Leaves generally distorted and thickened | Poplar vagabond aphid (Mordwilkoja vagabunda) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Hollow swellings on new shoots | Petiole-gall aphids (Pemphigus spp.) |
Terminal leaves distorted into thickened mass | Poplar vagabond aphid (Mordwilkoja vagabunda) |
Twigs shredded in irregular row | Cicada oviposition injury (Platypeisidae) |
Swellings in twigs, small branches | Poplar gall borer (Superda inornata) or Hail injury (upper surface only) |
Scales on twigs, branches | Oystershell scale (Lepidosophes ulmi) |
Catkins grossly distorted and enlarged | Cottonwood catkin gall mite (Eriophyes neoessigi) |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (various species) |
Open wounds, internal decay, swollen areas in stem | Stem decay fungi (various species) |
Masses of caterpillars resting on bark | Forest tent caterpillar (Malacosoma disstria) |
Tunneling in trunk, often with orange staining ooze | Cottonwood borer (Plectodera scalator),Poplar borer (Saperda calcarata),Cottonwood Crown Borer, or American hornet moth (Sesia tibialis) |
Clear to white oozing or frothy malodorous liquid exiting from wounds | Bacterial wetwood/slime flux |
Areas of dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Insects visiting oozing sap from trunk | Flies (various families) |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms: | Cause: |
White root decay with white mycelial fans between bark and wood | Armillaria root disease(Armillaria mellea) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
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Affecting Leaves and Stem: | |
Signs or Symptoms | Cause |
Large gray-brown spots with concentric rings; spots merge and cover entire leaf | Early blight (Alternaria spp.) |
Water-soaked brown lesions on lower leaves first | Late blight (Phytophthora infestans) |
Light-green to yellow leaves with lower leaflets rolled upwards | Leaf roll virus |
Yellow, mottled leaves accompanied by crinkling | Mosaic virus |
Yellow leaves, stem black below soil line | Blackleg (Erwinia caratova) |
Yellow, puckered, curled leaves | Potato aphids |
Yellow, stippled, stunted leaves | Leafhoppers |
Holes in leaves are large; whole leaflets consumed | Colorado potato beetle (Leptinotarsa decemlineata) |
Small holes in leaves | Flea beetles (Phyllotreta spp.) |
Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Sprouts die before emergence | Rhizoctonia (Rhizoctonia spp.) |
Yellow, stunted plants | Root-knot nematodes (Meloidogyne spp.) |
Yellow leaves, gradual wilting usually at flowering | Verticillium wilt (Verticillium spp.) |
Plants wilt suddenly | Wireworms |
Affecting Tubers: | |
Signs or Symptoms | Cause |
Brown to black raised spots on potato | Rhizoctonia (Rhizoctonia spp.) |
Rough, raised lesions on potato | Potato scab |
Enlarging brown to black blotches on potato; internal tissue is brown and dry just below the surface | Early blight (Alternaria spp.) |
Tiny surface trails (or tunnels) just beneath potato skin | Tuber flea beetle larvae (Phyllotretaspp.) |
Dark, internal lesions on potatoes | Phosphorus or potassium deficiency |
Dwarfed potatoes | Calcium deficiency |
Green coloration of tubers | Exposure to light. Keep developing tubers covered with soil. |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Edge of leaves cut in semicircle | Leafcutter bees (Megachile spp.) |
Edge of leaves notched | Black vine weevil (Otiorhynchus sulcatus) |
Leaves with blotchy mines | Lilac leafminer (Caloptilia syringella) |
Leaves blackened and wilted | Bacterial blight (Pseudomonas syringaepv. syringae) |
White powdery material on upper or lower surface of leaf | Powdery mildew (Microsphaera penicillata) |
Leaves turn a rusty color | Rust mites |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Scales | Oystershell scale (Lepidosaphes ulmi) |
Borers | Lilac/ash borer (Podosesia syringae) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Stippling of leaves | Spider mites (Tetranychidae spp.) |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Twig blight/dieback | Fireblight (Erwinia amylovora) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed | Snailcase bagworm (Apterona helix) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Orange pustules on leaf | Leaf rust |
Affecting Stems, Twigs or Small Branches: | |
Signs or Symptoms | Cause |
Frothy mass on stems | Spittlebug (Clastoptera spp.) |
Cottony balls on stems | Rabbitbrush gall flies (Aciurina bigeloviae) |
Green flowerlike swellings | Rabbitbrush gall flies (Aciurina bigeloviae) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow v-shaped spots on leaf margins with blackened veins | Black rot (Xanthomonas campestris |
Yellowish leaves, lower leaves drop; stunted plants may have twisted stems; usually occurs soon after transplanting | Fusarium yellows (Fusarium oxysporum) |
Yellow leaves, older first; stunted plants | Nitrogen deficiency |
Yellow, curled leaves; stunted plants | Aphids |
Purplish patches on leaves | Phosphorus deficiency in cool soils |
Small leaf holes | Flea beetles (Phyllotreta spp.) |
Large leaf holes | Cabbage Loopers or Imported Cabbage Worms (Pieris rapae) |
Affecting Roots: | |
Signs or Symptoms | Cause |
Yellow, stunted plants that wilt during bright, hot days and recover at night | Root injury. Check for root maggots. |
Small, imperfectly formed roots | Nitrogen deficiency |
Poor root development | Phosphorus deficiency |
White spots or streaks internally; large air spaces and tough, dry roots | High temperature injury |
Soft, shriveled roots | Freezing injury |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
New leaves and shoots have a powdery appearance. Later, light brown to orange pinhead-sized balls form within the mass of white growth. These tiny dots mature and turn a black color. These black structures are the overwintering stage. | Powdery Mildew |
Leaves on infected plants are uniformly small, dark green, crinkled, and tightly curled downward and inward. When diseased shoots first appear, they are pale yellowish-green, but they soon turn dark green, become stiff and brittle, and usually do not branch.Plant lose vigor each year. Berries on infected plants may ripen prematurely and are small, dry, seedy, and crumbly. | Raspberry Leaf Curl Virus. Infected plants should be destroyed immediately. |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Larvae bore many tunnels in canes and the crown may be extensively damaged | Raspberry Crown Borer |
Affecting Roots and Ground Line Area: | |
Signs or Symptoms | Cause |
The most obvious symptoms of root rot are stunted, yellowing leaves, premature fall coloration and leaf drop, and twig and branch dieback. By the time the foliar symptoms develop, the rot canker may extend halfway or more around the stem of the plant. In early stages, the diseased bark is firm and intact while the inner bark is slimy and may produce a moist, gummy exudate. | Phytophthera Root Rot |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Worm Like grubs inside raspberries Prune out old canes as soon as they fruit and cultivate around plants The adults cause characteristic slits in the leaves from their feeding and destroy developing buds. The larvae feed within the blossoms and inside developing fruit. |
Western Raspberry Fruitworm |
Affecting Whole Plant: | |
Foliar symptoms typically include wilting, curling, yellowing, marginal or interveinal browning or death. Often these symptoms may look like water stress and can occur on only one side of the plant. Other symptoms may include dieback of branches or a portion of the plant. Furthermore, wood under the bark may exhibit discolored streaks or bands. The color of the streaks can range from light tan to grayish olive to brownish-black. Yellowing and defoliation often progress upward. | Verticillium Wilt |
Brown, irregular, blotchy area that expands between leaf veins. Black, sunken spots develop on fruits, leaves, and stems of vegetables. |
Anthracnose |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, curling leaf margins, wilted plants | Leaf hoppers |
Yellow leaves, slow growth | Nitrogen deficiency |
Wilting, yellow leaves, marginal leaf browning | Verticillium wilt (Verticillium spp.) |
Small, round, brown spots on leaves | Fungal disease |
Affecting Stalks: | |
Signs or Symptoms | Cause |
Holes chewed in stalks | Worms, including European corn borer(Ostrinia nubilalis) and Imported Cabbage worm(Pieris rapae) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
White powdery material on upper or lower surface of leaf | Powdery mildew (Sphaerotheca pannosa) |
Leaves with white spotting | Rose leafhopper (Edwardsiana rosae) orTwospotted spider mite (Tetranychus urticae Koch) or Rust (Phragmidium mucronatum) |
Small ball-like growths on leaves, usually reddish | Gall wasps |
Leaves mottled with yellowish areas | Iron chlorisis or Rose mosaic complex(various viruses are responsible) |
Orange-red colored patches on lower leaf surface | Rose rust |
Angular brown spots on leaves | Anthracnose |
Interior areas of leaves chewed | Roseslug and other sawflies (Endelomyia aethiops) |
Even, semicircular cuts in leaf edge | Leafcutter bees (Megachile spp.) |
Leaves curled | Powdery mildew or Aphids |
Dark spots on leaves | Black spot (Diplocarpon rosae) |
Affecting Canes: | |
Signs or Symptoms | Cause |
Insects tunneling into pith of cane | Leafcutter bees (Megachile spp.) |
Exterior area of cane girdled, sometimes with associated dieback | Bronze cane borer / Rose stem girdler(Agrilus aurichalc) |
Mossy or ball-like growths on stem | Gall wasps (Diplolepsis sp.) |
Woody, tumor-like growth, usually on lower stem | Crown gall (Agrobacterium tumefaceins) |
Swellings in canes, often with associated vertical cracking | Bronze cane borer / Rose stem girdler(Agrilus aurichalceus) |
Purple to tan, sometimes sunken spots on canes | Rose canker (Cryptosporella orLeptosphaeria sp.) |
Affecting Flower: | |
Signs or Symptoms | Cause |
Flower buds killed, fail to emerge (blind shoots) | Rose midge (Dasineura rhodophaga); Fluctuating, cool temperatures; or Rose curculio (Merhynchites bicolor) |
Flower petals scarred | Flower thrips (Thysanoptera spp.) |
Flower petals chewed or tunneled | Earwigs (Forficula auricularia L.), Rose curculio (Merhynchites bicolor) |
Flowers produced are off-type after winter (Grandiflora and hybrid tea roses) | Die back to the grafted rootstock |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Orange leaf spots, defoliation and fruit and twig deformities. | Cedar Apple Rust |
Affecting Twigs: | |
Signs or Symptoms | Cause |
Twigs in short thick clumps | Witches broom (Apiosporina collinsii) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow area on leaf upper surface with blue-gray patches on undersides of leaves | Downy mildew (Peronospora effusa) |
Young center leaves turn yellow and curl, followed by mottling, browning, and death of larger leaves | Tobacco Mosaic Virus |
Yellow deformed leaves that eventually die, along with stunted plants | Curly-top |
Yellow curled leaves and stunted growth | Aphids, usually green peach aphids |
Light-colored winding tunnels in leaves; becomes an enlarged blotch at the ends of leaves which may turn white or brown | Spinach leaf miner |
Small holes in leaves, undersides of leaves may be skeletonized | Flea beetles (Phyllotreta spp.) |
Ragged holes in outer leaves, usually between leaf veins | Cabbage looper and/or Beet armyworm |
Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Seeds do not germinate; a poor stand despite using fresh seed and maintaining proper germination conditions | Damping off Pythium, Rhizoctonia, and other fungi) |
Young plants stunted and yellow along with gradual wilting of older plants | Fusarium wilt (Fusarium oxysporum) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Insect on leaves, sometimes associated with leaf curls | Spirea aphid (Aphis citricola) |
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Affecting Needles: | |
Signs or Symptoms | Cause |
New needles being chewed | Douglas-fir tussock moth (Orgyia pseudotsugata) or Western spruce budworm (Choristoneura occidentalis) |
Needles chewed and fragments tied with webbing | Spruce needleminer (Endothernia albolineana) |
Brown felt-like material on needles, branches (high elevation) | Brown felt blight (Herpotrichia juniperi) or Snow mold |
Needles being mined | Spruce needleminer (Endothenia albolineana) |
Aphids on needles | Giant conifer aphids (Cinara spp.) |
Needles become grayish, with small flecks | Spruce spider mite (Oligonychus ununguis) |
White scales on needles | Pine needle scale (Chionaspis pinifoliae) |
Brown needles with dark fruiting bodies | Needlecasts (Lophodermium sp. and others) |
Needles to exterior of tree bleached or brown, developing late winter | Winter dessication |
Needles on branch turn reddish brown | Cytospora canker (Valsa spp.,Leucostoma spp.) or Root injury |
Mottled yellowing of needles on a branch | Winter exposure injury |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Twigs distorted into cone-like gall | Cooley spruce gall adelgid (Adelges cooleyi) |
Woolly aphid on underside of twigs in spring | Cooley spruce gall adelgid (Adelges cooleyi) |
Small bud-like scales on twigs | Spruce bud scale |
Large aphids on branch | Giant conifer aphids (Cinara spp.) |
Resinous canker on branch | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Bark beetles | Spruce beetle (Dendroctonus rufipennis) or Spruce ips (Ips hunteri Swaine) |
Aphids | Giant conifer aphids (Cinara spp.) |
Open wounds, internal decay, swollen areas in stem | Stem decay fungi (Phellinus pini,Inonotus circinatus, Fomitopsis pinocolaand various fungal genera) |
Fungal fruiting bodies (mushrooms, conks) present | Stem decay fungi (Phellinus pini,Inonotus circinatus, Fomitopsis pinocolaand various fungal genera) |
Affecting Top of Tree: | |
Signs or Symptoms | Cause |
Wilting and dieback restricted to terminal, shepherds' crook | White pine weevil (Pissodes strobi) |
Upper crown defoliated | Douglas-fir tussock moth (Orgyia pseudotsugata) |
Upper crown dieback | Spruce ips (Ips hunteri Swaine) |
Affecting Roots: | |
Signs or Symptoms | Cause |
White root decay with white mycelial fans between bark and wood | Armillaria root disease (Armillaria mellea) |
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Affecting Leaves and Vines: | |
Signs or Symptoms | Cause |
Plants wilt, foliage looks burned; preceded by pale green areas forming on leaves | Squash bug (Anasa tristus) |
Sudden wilting of a runner or part of a runner | Squash vine borer (Melitta satyriniformis) |
Leaves wilt, yellow, and curl | High Aphid populations |
Vines wilt and die gradually, starting with newer leaves; no leaf yellowing is present | Bacterial wilt (Erwinia tracheiphila) |
Small, pitted leaf holes on young plants | Cucumber beetles (Acalymma vittata) |
Distorted, Yellow spots on leaves with mottling and wrinkling of older leaves | Mosaic viruses |
Older leaves mottled yellow between veins | Downy mildew (Peronospora effusa) |
Powdery, white spots on upper surface of leaves especially | Powdery mildew |
Leaf spots that begin as water-soaked, then turn gray, die and drop out leaving foliage with a shot-hole appearance | Angular leafspot (Pseudomonas syringae) |
If water-soaked, yellow spots turn brown | Anthracnose |
Leaves are yellow and puckered and become bronzed | Mites |
Dark brown spots with concentric rings on older leaves first; vines defoliate eventually | Alternaria leaf blight (Alternaria spp.) |
Spots with pale, round centers and dark margins on upper surface of leaves | Cercospora leaf spot (Cercospora spp.) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Small, brown, angular fruit spots | Angular leafspot (Pseudomonas syringae) |
Brown and sunken zoned spots | Alternaria (Alternaria spp.) |
Circular, black, sunken cankers | Anthracnose |
Misshapen, yellow mottled fruit, often with a bitter taste | Mosaic virus |
Fruit wilts and shrivels | Bacterial wilt (Erwinia tracheiphila) |
Fruit is narrow at stem end | Potassium deficiency |
Fruit has a dull bronze color | Phosphorus deficiency |
Fruit is light colored | Nitrogen deficiency |
Dark pitting of fruit | Cold damage |
- Details
Stone Fruits: Apricot, Cherry Chokecherry, Peach, Plum, etc. (Prunus spp.)
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Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Tree decline in vigor | Phytophthora root rot (Phytophthoraspp.), Cytospora Canker (Valsa spp.,Leucostoma spp.), or Verticillium wilt(Verticillium spp.) |
Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves chewed, no associated webbing | Pearslug (Caliroa derasi) |
Upper surface of the leaf skeletonized | Pearslug (Caliroa cerais) or Apple Thorn Skeletonizer |
Webbing associated with chewing | Fall webworm (Hyphantria cunea Drury),Ugly Nest caterpillar (Archips cerasivorana), or Western tent caterpillar(Malacosoma californicum) |
Leaves with small, circular holes | Shot hole disease |
White flecking injuries | White apple leafhopper (Typhlocyba pomaria McAtee) or Lacebug (Corythuca padi), on chokecherry (Corythuca spp.) |
White powdery material on upper or lower surface of leaf | Powdery mildew |
Leaves yellow | Iron chlorosis or X-disease |
Leaves with small, pouch or finger-like projections | Fingergall mites (Phytoptus species) |
New leaves curled | Aphids: Green peach aphid (Myzus persicae), Leafcurl plum aphid (Anuraphis helichrysi), or Black cherry aphid (Myzus cerasi) |
New leaves curled and thickened and red/purple | Peach leaf-curl disease |
Affecting Larger Branches or Trunks: | |
Signs or Symptoms | Cause |
Black galls on branches | Black knot of cherry (Apiosporina morbosa) |
Stem decay and/or hoof-shaped fruiting body (conk) | Decay fungus (Phellinus pomaceus) |
Scales | Scale: European fruit lecanium (Parthenolecanium corni) or Oystershell scale (Lepidosaphes ulmi) |
Small pinhead-sized exit holes in branches | Shothole borer (Scolytus rugulosus) |
Branches die back | Cytospora canker (Valsa spp.,Leucostoma spp.) or Shothole borer (Scolytus rugulosus) |
Gumming and dark colored branches | Shothole borer (Scolytus rugulosus), or Cytospora canker (Valsa spp.,Leucostoma spp.) or Bacterial Blight (Pseudomonas syringae) |
Dead bark with discoloration and small pimple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of tree, originating from roots | Verticillium wilt (Verticillium spp.) |
Affecting Ground Line Area of Trunk: | |
Signs or Symptoms | Cause |
Discolored tissue under bark at ground line | Phytophthora root rot (Phytopthora sp.) |
Gall at ground line | Crown gall (Agrobacterium tumefaciens) |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Fruit tunneled | European earwig (Forficula auricularia L.) |
Fruit with sunken, corky areas | Plant bug (Lygus species), Hail injury, or Boxelder bug (Boisea trivittata) |
Puncture wounds in fruit | Bird damage (Robins, finches, etc.) |
Chokecherry fruit enlarged, hollow | Chokecherry gall midge (Contarinia virginianae) |
Maggots in cherry fruit | Western cherry fruit fly (Rhagoletis indifferens Curran |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Yellow, distorted leaves. | Aster yellows virus |
Small, deep purple, round to elongate spots on leaves and sometimes on fruit. Spots enlarge and develop light-colored centers. Relative humidities of 98-100% and temperatures of 59 to 77º F promote infection. Middle-aged leaves appear to be most susceptible. Plant on raised beds and avoid sprinkler irrigation. | Common leaf spot (Mycosphaerella fragariae). |
Yellow stippled to bronzed-colored leaves. | Spider mites |
White frothy areas on leaves and stems. | Spittle bugs |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Senescent leaves, fruits, and petals are susceptible. Under cool (60 - 70° F.), moist conditions a soft, brown decay develops, covered by a dense gray to light brown mass of spores. | Gray Mold (Botrytis cenerea) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Small reddish swellings | Eriophyid mite gall |
Affecting Twigs: | |
Signs or Symptoms | Cause |
Dark insects on twigs | Oystershell scale (Lepidosaphes ulmi) |
Affecting Stems and Branches: | |
Signs or Symptoms | Cause |
Discolored areas, dead bark containing small pinmple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Wilting and dieback of portions of plant originating from roots | Verticillium wilt (Verticillium spp.) |
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Affecting Leaves: | |
Signs or Symptoms | Cause |
Leaves with blackened spotting | Anthracnose (Apiognomonia veneta) |
Affecting Twigs and Smaller Branches: | |
Signs or Symptoms | Cause |
Discolored areas, dead bark containing small pinmple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Witches' broom with dead small branches | Anthracnose (Apiognomonia veneta) |
Affecting Larger Branches or Trunk: | |
Signs or Symptoms | Cause |
Discolored areas, dead bark containing small pinmple-like fruiting bodies (pycnidia) | Cytospora canker (Valsa spp.,Leucostoma spp.) |
Clear to white oozing or frothy malodorous liquid | Bacterial wetwood / Slime flux |
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Affecting Leaves and Stems: | |
Signs or Symptoms | Cause |
Young leaves turn yellow between veins | Iron deficiency, usually on soils with high pH |
Younger leaves pale, terminal buds die | Calcium deficiency |
Leaves on young plant are purple | Phosphorus deficiency |
Older leaves pale, small, general yellowing | Nitrogen dificiency |
Older leaves turn yellow between veins while veins remain green, then become bronzed | Potassium deficiency |
Yellow, mottled leaves; curling and malformation giving terminals a fernlike appearance | Mosaic virus |
Black to brown angular to circular small spots (without concentric zones). | Bacterial Spot |
Brown spots, distorted leaves and stems; stunted and sticky leaves covered with a black film | Aphids |
Leathery, black-brown spots with concentric rings; lower leaves and stems affected first; occurs during humid/wet, warm conditions | Early Blight |
Black-green water soaked areas on older leaves, branches, and stems, usually in humid/wet cooler weather (60-70° F.) | Late Blight |
Small to large round holes in leaves, plants and leaflets stripped | Colorado Potato Beetle |
Whole leaves consumed | Tobacco hornworms |
Small pitted holes, shot-hole injury | Flea beetles (Phyllotreta spp.) |
Leaves have irregular chew holes giving the leaves a ragged appearance | Cabbage Looper |
Affecting Whole Plant: | |
Signs or Symptoms | Cause |
Yellowing and flagging of shoots and leaves at base of plant first. Cross section of infected stem has reddish-brown vascular system. Occurs when temperature is 80-90° .F | Fusarium wilt |
Yellowing and gradual wilting; leaf margins curl upwards; light brown discoloration of vascular system. Occurs at 68-75° F. | Verticillium Wilt |
Young plants cut off at soil line | Cutworms |
Whole plant yellows, wilts and dies. Check roots. | If galls on roots up to 1 inch in diameter,Root-knot nematodes |
Affecting Fruit: | |
Signs or Symptoms | Cause |
Large chunks of green fruit consumed | Tobacco and tomato hornworm or Colorado potato beetle |
Small holes on fruit surface with a messy, watery, rotten internal cavity. Fruit appears to collapse like a balloon | Tomato fruitworm, also called Corn earworm |
Dark pinpricks surrounded by light areas; white, spongy area below spots | Stink bugs |
Scarring and malformation of fruit, especially at blossom end | Catfacing |
Yellow or white blister-like patch on fruit, usually on side exposed to the sun |