Maple: Powdery mildew

categories: Maple Maple Diseases Ornamental trees Ornamentals

revision date: 2024-06-05 10:40

White substance covering top surface of maple leaf.
Powdery mildew on maple
Photo by: R.S. Byther


Powdery mildew of maple is a fungal disease which affects many hardwoods including maple, hazel, birch, and alder. On maples, a characteristic white, fuzzy or powdery growth appears on the upper or lower surfaces of mature leaves. Sometimes small black structures may be observed in the white areas. Shoots which develop late in the season may be distorted as a result of the infection.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

  • Watch for signs of infection during appropriate weather conditions (dry weather, warm days, and cool nights).
  • Pick off infected leaves, when practical, to prevent spread of the disease.
  • Gather and destroy fallen leaves.
  • Space plantings and prune to provide good air circulation.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • Apply when the first symptoms appear.
  • Homeowners should not make foliar applications to trees over 10 ft tall.
  • Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.


Approved Pesticides

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.