Oak anthracnose, caused by the fungus Apiognomonia quercina , attacks many species of oaks including bur, white, swamp white, English, pin, northern red, and chestnut oak. The susceptibility varies among species, with white and bur oaks usually the most severely affected. The first symptom seen in the spring is usually shoot blight, which can develop suddenly following rain. Young leaves and shoots appear brown and shriveled while the leaves that have already expanded may become cupped and distorted with large areas of dead tissues. Small, brown fruiting bodies,called acervuli, may become visible on the lower surface of the dead leaves on or near major veins and leaf drop may occur.
Mature leaves are fairly resistant and infection causes only small necrotic spots.
The fungus also infects twigs, producing cankers and causing twig dieback during the winter and early spring. Several species of fungi cause maple anthracnose. The symptoms caused by K. apocrypta appear following infection during cool, wet weather throughout the spring and summer. Infected young leaves and shoots may shrivel and turn black. On more mature leaves, red, brown, tan, or black lesions develop that may or may not be associated with leaf veins.