WSU Extension

Hortsense

Caption: Maple anthracnose
Photo by: R.S. Byther
  
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Maple : Anthracnose
(revision date: 4/11/2018)


Biology
Maple anthracnose is a fungal disease affecting leaves and sometimes twigs. Infected leaves develop discrete brown spots and/or blotches, often at leaf tips and often associated with the main or secondary veins. Japanese maples tend to develop reddish-brown to light tan blotches. Small brown fruiting bodies may be seen in the affected areas. Diseased leaves of all maples may drop prematurely, sometimes resulting in severe defoliation. The disease occasionally causes twig cankers, where the fungus can overwinter. Cankers may also girdle twigs, causing tip dieback. The disease is favored by warm, wet springs.
Management Options

Non-Chemical Management
  • Rake and destroy all fallen leaves.
  • Prune out and destroy infected twigs during the dormant season.
Select non-chemical management options as your first choice!

Chemical Management


If needed, apply in spring during budbreak and early new growth. 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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • Bonide Fung-onil Multi-Purpose Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 60063-9-4
  • ferti-lome Broad Spectrum Landscape & Garden Fungicide
    Active ingredient: chlorothalonil  |  EPA reg no: 60063-16-7401
  • This list may not include all products registered for this use.
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Caption: Maple anthracnose
Photo by: R.S. Byther