Description
    Powdery mildew is a common disease on many plants and is caused by many different, closely related species of fungi.

    The fungus attacks leaves, buds, and young shoots covering diseased parts with a white powdery-looking mass of spores. The disease develops best in warm weather and humidity.

Injury
    Heavily diseased leaves may shrivel up and turn brown. However, its occurrence on black walnut is rare.

Control
    No control is recommended.