In wet years the disease causes severe defoliation. The symptoms are large reddish brown spots on the upper leaf surface but brown on the lower surface. The spots may not have distinct marginal markings. The disease overwinters on fallen diseased leaves so dispose of infected leaves in the fall. A large number of fungi cause leaf spots on hickory.
Severe infections can cause defoliation.
Many of the fungi overwinter on diseased leaves, dispose of infected leaves when they fall. Witches broom can follow a leaf spot disease caused by Microstroma juglandis. Symptoms are yellow blotches on the upper sides of the leaves but white on the undersides. Severe infections may cause defoliation and when the fungus invades the stem a witches broom forms. Leaves on the stems of the witches broom are yellowish, small, and fall prematurely.