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Table: Diagnosis and Control of Maple Anthracnose
Pest Identification Host Plants Damage Symptoms
Anthracnose of Maple
Kabatiella apocrypta
Maples Symptoms associated with maple anthracnose include brown necrotic spots or a scorching of the leaves. Occasionally anthracnose may cause a blight of young twigs. Infected young leaves may appear blackened and necrotic, while older mature leaves (more resistant) may only appear spotted. Anthracnose may cause partial defoliation of trees, and is most severe during cool wet weather.
Monitoring Control Options Pesticides
Maple trees should be monitored for anthracnose early in the spring, especially during periods of cool, wet weather. Watch for necrotic spots to develop on leaves. Anthracnose should become less active as the season progress (warms and dries). Anthracnose is usually considered a cosmetic disease that does not require chemical control. In severe cases where anthracnose has defoliated the tree for 3 out of 5 years, chemical control may be warranted. A fungicide spray using thiophanate-methyl at the time of bud break and again 7 to 10 days later should effectively control this disease. Additional sprays can be applied during cool wet weather, according to the label. More than one year of control may be needed. Additional control measures include pruning infected branches and cultural practices to increase the vigor of the tree. Sanitation and eradication appear to be of little value. Thiophanate-methyl
(Clearys 3336)
Description and Life History
Description: Anthracnose is a fungal, foliar disease that infects the leaf tissue, and shoots. Anthracnose can cause blight of leaves and shoots, and possibly twig dieback. Spores form in acervuli on infected tissue.

Life history: Anthracnose is activated in the spring during cool wet weather. This disease has not been extensively studied and therefore the source of inoculum is unknown. It is assumed that spores overwintering in the tree or on the ground cause the initial infection. Initial infections occur on the leaves, causing brown, necrotic spots or scorching. Occasionally anthracnose may cause blight on twigs.

Overwintering: This disease has not been extensively studied and it is unknown how the fungus overwinters.


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Last modified on March 07, 2013