University of Maryland Extension

Shade tree anthracnose - Trees

leaf lesion on maple

Maple anthracnose

Back to Common Problems - Trees and Shrubs

These diseases are characterized by discrete lesions that are usually found along leaf veins. In severe cases these lesions may run together and kill the entire leaf. Young leaves may become distorted as healthy tissue continues to grow around dead areas. Under optimum disease conditions the entire tree may be defoliated in the spring or early summer. Infection may proceed from the leaf blade down the petiole (leaf stem) into the small twigs at the tips of the tree branches. The pathogen may over winter in the twigs until the infection cycle starts over the next spring. Common examples are oak anthracnose, maple anthracnose , and sycamore anthracnose.

sycamore anthracnose symptom sycamore anthracnose canker on a twig

Infection may proceed from the leaf blade down the petiole (leaf stem) into the small twigs at the tips of the tree branches

Management strategies: In most cases as mentioned above anthracnose leaf diseases on mature trees will not be a major problem threatening the health of the tree. The best management practices involve pruning and removal of dead twigs during the winter or dry summer months. Mature trees can be thinned for better air circulation throughout the canopy. Rake and remove infected fallen leaves in the fall and plant resistant varieties when available.

It is generally not economical to spray large mature shade trees for anthracnose diseases nor is it effective once disease symptoms are noticeable. Young trees or newly planted trees may need fungicide sprays to prevent excessive leaf loss until they become established in the landscape.

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