The most prevalent one, Kabatiella apocrypta , attacks Norway, red, silver and sugar maples, and boxelders. Leaf lesions and distortion caused by 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. Leaves may become crinkled or otherwise deformed.
Lesions often coalesce and kill large areas of leaf tissue.
In severe cases defoliation may occur. Walnut Anthracnose Walnut anthracnose is common on black walnut in Nebraska in areas where the weather is often warm and humid. It is caused by the fungus Gnomonia leptostyla . Spotting, yellowing, and premature leaflet drop caused by walnut anthracnose. Symptoms of walnut anthracnose begin to appear in late spring on leaves that have reached full size.