Disease

Shade tree anthracnose

Apiognomonia, Discula and related fungi

Fungi that blotch the young leaves of maple, ash, sycamore, oak and dogwood in cool, wet springs. Trees often drop many leaves, then grow a second set. It looks worse than it is, except on dogwood.

Signs

• Irregular tan to brown blotches along and between the veins, on the first leaves of spring.
• Leaves distorted where the blotches meet; heavy leaf drop in late spring.
• New leaves that come out in warmer, drier weather are usually healthier.

What favors it

Cool, wet weather while leaves are opening in spring; dense crowns that stay wet.

Prevention

• Rake and remove fallen leaves and twigs.
• Prune to open dense crowns, in dry weather.
• Choose resistant species: London plane over sycamore, kousa dogwood over flowering dogwood.

Crops it shows up on

Shade & ornamental trees.

Often confused with

Sources

• AnthracnoseMontana State University Extension
• Anthracnose [Trees and Shrubs]University of Illinois Extension
• Anthracnose of Shade TreesUniversity of Illinois Extension
• Anthracnose of Shade TreesIowa State University Extension
• Sycamore AnthracnoseUniversity of Arizona Cooperative Extension
• Dogwood AnthracnoseUMass Amherst Extension

Why →