Defoliation also may occur. Young shoots that become infected may suddenly wilt and shrivel, especially following a rain. This symptom is sometimes confused with spring freeze injury. The fungus can also grow from leaves into twigs and develop as a canker. Oak Anthracnose 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.
Susceptibility varies among species, with white and bur oaks usually the most severely affected.
Leaf distortion caused by oak anthracnose lesions. 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. Some leaf drop may occur. Mature leaves are fairly resistant and infection causes only small necrotic spots.