Even though the growing season is in full swing now, some tree species are losing their leaves. The extended cool, wet weather this spring has created prime conditions for foliar diseases, especially anthracnose and apple scab.
Symptoms occur on sycamore, ash, maple, oak, walnut, linden, hickory, and other deciduous trees.
Anthracnose is caused by a number of different but closely related fungi. Each fungus is specific to the host tree it infects. Anthracnose on walnut will not cause anthracnose on ash, as so on. In most cases symptoms may appear serious, but damage caused by anthracnose is minimal and does not seriously harm established shade trees. Symptoms vary from small, circular to irregular spots that are tan, dark brown, or black, to larger blotches that are usually associated with midribs and veins.