The Village of Carol Stream has been notified that rhytisma acerinum (Maple Tree Tar Spot) has been diagnosed in neighboring communities. While cosmetically unpleasant, Tar Spot does not affect the overall health of the Maple tree.
The fungus appears as a tar-like black spot on Maple leaves and can grow throughout the season. The spread of this fungus can be controlled, if you see this on your leaves please do not mulch them. Instead, please bag affected leaves and put them out with your yard waste.
For further information please follow this link. https://natlarb.com/html/tar_spot_of_maple_tree.html