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Anthracnose of Shade Trees



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Gail Ruhl, Plant Disease Diagnostician

Anthracnose is the common name for a type of leaf spot and canker disease caused by certain kinds of fungi. Anthracnose diseases affect many trees, but are particularly prevalent on white oak, ash, maple, walnut and sycamore. Each species of tree is infected by a different species of fungus, thus the fungus does not spread from oak to maple or maple to ash or ash to sycamore. A different fungal species is also responsible for dogwood anthracnose.

Symptoms are especially severe in years with cool, wet spring weather. The symptoms will vary depending on the type of tree and the stage of plant development at the time of infection: leaf spots or blotches; twig dieback and wilting; and browning or death of emerging leaves are all possible. Premature leaf drop often occurs with anthracnose diseases, however, most of the trees infected with anthracnose usually show good resilience, and are not permanently damaged by this early season leaf blight.

Sycamore anthracnose has severely blighted newly emerging leaves and shoots. Twig and branch cankers, shoot blight, and leaf blight are all symptoms of the fungus that causes sycamore anthracnose. Leaflet drop, as well as dead tissue along leaf veins or at the leaf edges is a symptom for ash anthracnose. Although defoliation may be so great that anthracnose-infected leaflets practically carpet the walks and lawns nearby, the tree is not dying, it simply puts out a new set of leaves.

Anthracnose symptoms on maple and oak range from leaf spots to shoot blight and shoot cankers.

Anthracnose Management in Landscape Trees

Anthracnose infected trees need to refoliate, and regeneration of carbohydrate reserves can be hampered by drought. Thus, it is important for these landscape trees to get off to a good start in the spring. Although we have not been able to control the weather, there are some cultural practices that may help.

For more information refer to Anthracnose of Shade Trees - BP-9-W (PDF 493K) and Dogwood Anthracnose.

Click on the small image to view a larger image.

Anthracnose of Sycamore Anthracnose of Ash
Anthracnose of Sycamore
(Photo by Peggy Sellers)
Anthracnose of Ash
(Photo by Peggy Sellers)
Anthracnose of Maple Anthracnose of Oak
Anthracnose of Maple
(Photo by Peggy Sellers)
Anthracnose of Oak
(Photo by Peggy Sellers)

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