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Tar Spot on Maples
Tar Spot on Maples
Tar Spot on maples is an occasional tree disease that can cause concern for customers who have maple trees on their property, especially Norway, Red and Silver Maples. The black spots look like someone spilled tar in big drops on the leaves and can cause the leaves to fall early in August or September.
Tar Spot begins in the spring or early summer and develops light green to yellow green spots on the upper leaf surface. During the summer, black, tar-like structures form within the yellow spots. The spots can range in size from a quarter inch to 1 inch in diameter.
The disease can cause early leaf drop, but it has little detrimental effect on the trees. The best thing to do is to rake and clear away the diseased leaves to remove the source of infection for the following year. This may be the most difficult aspect when it comes to dealing with this disease. Usually, I recommend that people mulch their leaves in the fall to reincorporate the organic material back into the soil. If your tree has a problem with Tar Spot, especially if it occurs year after year, raking and disposing of the leaves will help reduce the incidence of the disease.