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

Oak anthracnose is a fungal disease of leaves and twigs of many species of oak. Typical symptoms include the presence of small to large brown lesions on the leaves, usually along the midrib or main veins. Half or more of a leaf may be killed. Young leaves may be severely deformed (curled, puckered, or twisted) by infections occurring during development. Twigs may develop cankers and die back. The fungus may be visible as small brown specks on the lower surface of infected leaves or as pustules on infected twigs. Infections of mature, more resistant leaves are often limited to small brown spots. Premature leaf drop may occur. The disease is favored by prolonged moisture at the time leaves are developing. Symptoms first appear on lower part of tree and progress upward. The fungus may infect and girdle twigs causing dieback.
Management Options

Non-Chemical Management
  • Rake and destroy fallen leaves during summer and fall.
  • Prune and destroy diseased branches, when practical, to reduce overwintering of disease.
  • Do not compost diseased material.
  • Avoid overhead watering.
  • Species in the black oak group are resistant to anthracnose.
Select non-chemical management options as your first choice!

Chemical Management

If fungicides are needed, apply in spring during budbreak and early shoot growth when wet weather is expected. Chlorothalonil products are registered for RED OAKS ONLY! 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
  • Bonide Infuse Systemic Disease Control
    Active ingredient: propiconazole  |  EPA reg no: 100-773-4
  • ferti-lome Liquid Systemic Fungicide II R-T-Spray
    Active ingredient: propiconazole  |  EPA reg no: 53883-184-7401
  • GardenTech Daconil Fungicide Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 67572-82-71004
  • Ortho Max Garden Disease Control Conc
    Active ingredient: chlorothalonil  |  EPA reg no: 239-2522
  • This list may not include all products registered for this use.

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Caption: Oak anthracnose
Photo by: R.S. Byther