Maple: Phyllosticta leaf spot

categories: Maple Maple Diseases Ornamental trees Ornamentals

revision date: 2022-11-25 09:50


Symptoms of Phyllosticta leaf spot on many maple species include the development of small (approximately 1/5 inch), roughly circular, brown spots with dark reddish or purplish borders. Japanese maples develop yellowish or tan spots, which sometimes have transparent centers. A circular pattern of black fungal fruiting bodies may be seen in the dead areas on infected leaves. On some maples, the diseased center portions of the leaf spots may fall out, giving a shothole appearance to the leaves. Infection occurs on wet leaves by water-splashed spores. Wet weather in spring and early summer favors disease development. The fungus probably overwinters on fallen leaves or on buds and twigs of host trees. This disease is not considered a serious landscape problem.

Management Options

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

Non-chemical Management

Select non-chemical management options as your first choice!

  • Rake and destroy fallen leaves.
  • Avoid overhead irrigation. If it is necessary to use overhead irrigation, water when foliage can dry quickly.

Chemical Management

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

  • Apply when leaf buds are opening and twice more at 10-day intervals if season is wet.
  • 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.