Walnut, English
Symptom Cause  
Irregular tan or brown spots on leaves at veins; expand until leaves die; sometimes sunken spots on leaves
Anthracnose (on plants)
>
Leaves wrinkled; stunted; leaves fall off
Aphids
>
Growth weak, sparse; leaves drooping, yellow, small holes, split at graft. Black, corky cells at graft
Black Line
>
Bark darkened at soil; sap oozes; sapwood discolored; foliage sparse, yellow;
Crown Rot
>
Young portions of foliage disappear, or young tips disappear, bark peeled off
Deer
>
Nutshells stained; frass around holes
Larvae of Codling Moth
>
Branches encrusted with elongated bumps
Oystershell Scales
>
Leaves covered with white powder
Powdery Mildew
>
Leaves eaten; trees defoliated
Redhumped Caterpillars
>
Branches encrusted with small bumps
Scale Insects
>
Black powdery sooty mold fungus forms on honeydew; branches may
Sooty Mold
>
Leaves stippled, yellowing or bronze; dry out and drop may be webbing visible; sometimes galls form on leaves
Spider Mites
>
Buds turn black; brown spots on leaves, dead lesions on shoots
Walnut Blight (bacteria)
>
Leaves eaten; trees defoliated
Walnut Caterpillars
>