Black Spot Maple Trees

Asked October 15, 2015, 5:56 PM EDT

Hi. I have two maple trees on my property in Centre County, PA that have these black spots on the leaves. I noticed them a few weeks ago. Not all of our maples have them. They are all more than 30 years old and 30 to 50 feet tall. In the area of these maples, I have a Hawthorne tree that I have been successfully treating for a rust issue for a couple years. Any help you can provide with treatment options or additional information is greatly appreciated. My best, Eric

Centre County Pennsylvania

3 Responses

Several different fungi in the genus Rhytisma infect the leaves of Maples and cause raised black spots to form on the leaf surfaces. The diseases are called "TAR SPOTS"because their appearance closely resembles droplets of tar on leaf surfaces.
They are rarely serious enough to threaten the health of a tree. Sometimes so many spots are on leaves that the tree becomes unsightly. Heavy infestation can cause early leaf drop. I am sending you some fact sheets where you can read more about symptoms/signs, disease cycle & management strategies
http://plantclinic.cornell.edu/factsheets/tarspotofmaple.pdf
http://hort.uwex.edu/articles/tar-spot/




You folks are the best! Thank you! (FYI - I originally went to my county MG web page and sent my question to the email address on their page, but they didn't get back to me. It would be nice to have the Ask and Expert option prominently on all the county MG web pages too).

I am with Bucks County so I cannot comment on other county practices. But I thank you for your appreciation and also I would like to say it was my pleasure and glad I could help.