Tar Spot on Maple

This week I have had numerous calls about black tar-like spots on maple trees throughout Hamilton County. The spots are not truly tar, they are in fact fungal leaf spots that are becoming noticeable that likely started forming after the rainy start we had earlier this summer.

Tar spots on maples are caused by fungi in the genus Rhytisma. Although tar spot disease may cause premature defoliation of leaves, seldom are they detrimental to the overall health of infected trees. Tar spot diseases are best managed by raking and destroying fallen leaves since the fungi overwinter on leaves.

There are a few other common foliage leaf infections found on maples, click here to read more about these diseases.