Walnut, Black
Symptom Cause  
Leaves curled and distorted
Aphids
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Sunken sores on trunks; branches
Bacterial Canker
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Many holes in branches; limbs girdled sawdust at holes
Borers
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Irregular dark spots on leaves
Brown Leaf Spot (fungus)
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Leaves eaten; trees defoliated
Caterpillars
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Corky galls at base of tree and roots
Crown Gall
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When young portions of foliage disappear, or young tips disappear; shredded bark on trunk
Deer
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Leaves eaten, silken nests spun by caterpillar; usually at end of branches
Fall Webworms
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Foliage turns pale or mottled
Lacebugs
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Nutshells stained; frass around holes
Larvae of Codling Moth
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Leaves chewed
Larvae of Tussock Moths
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Sooty mold, suck juices from leaves; may kill plant
Mealybugs
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Leaves stippled/yellow/bronze/dry out/Drop.  Webbing visible; leaf galls
Mite
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Young plant wilts, small roots gnawed
Pocket Gophers
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Leaves; branches encrusted with bumps; growth stunted
Scale Insects
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Black powdery sooty mold fungus forms on honeydew; branches may die
Sooty Mold
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Nuts disappear from tree
Squirrels
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Leaves yellow and curl
Zinc Deficiency
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