Potato, White
Symptom Cause  
Small, dark spots on leaves; eventually leaves turn black; fruits may blacken/drop
Anthracnose (on plants)
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Leaves wrinkled or curled; discolored, stunted, tend to fall off
Aphids
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Spots develop blights on leaves; eventually leaves may die; tubers develop puckered skin and shallow rough lesions; mold
Blight, Early
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Flowers, leaves, roots chewed
Blister Beetles
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Holes in leaves
Cabbage Loopers
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Holes chewed in leaves
Colorado Potato Beetle
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Holes chewed in leaves, leaf stalk, stems; plant wilts, dies.
Cucumber Beetles
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Plant gradually wilts, sawdust trail around stem
European Corn Borers
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Leaves riddled with shot holes; plant weakens
Flea Beetles
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Holes in leaves and flowers
Japanese Beetles
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Tip of leaves brown, internal larvae trails visible.
Leaf Miners
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Cottony white masses on roots, stems, branches leaves; reduced plant vigor
Mealybug
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Mottled, crinkled foliage; brown specks appear on fruit, and plants may droop and die prematurely
Mosaic Viruses
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Potatoes are eaten before picked
Pocket Gophers
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Foliage yellowed or white mottling, glaze of honeydew; plant weakens
Potato Leafhoppers
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Holes in flowers; leaves rolled up
Potato Leafroller
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Leaves yellowed and may drop
Potato Psyllids
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Plant stunted, leaves yellowed, lesions on roots
Root Knot Nematodes
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Young plants wilt in heat, may yellow and die.
Root Maggots
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Black spots, pitting on stem tips, buds, fruit
Tarnish Plant Bugs
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Leaves discolored; black fecal spots on underside of leaf.
Thrips
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Leaves skeletonized
Tomato Hornworm
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Late in season, older leaves yellow; affected vines die prematurely; stem tissue discolors from base; pink tubers
Verticillium Wilt
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Weakened plants; yellow leaves; leaves discolored; covered with honeydew
White fly
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Plant wilts, underground stems and roots chewed.
Wireworms
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