Tar spot are raised black circular deformations of maple leaves that begin as small yellow or black spots in early summer. The disease is primarily cosmetic and will not damage the tree, although it can be unsightly.
Fungal spores remain and mature on the maple leaves after defoliation in fall. It is recommended to remove, mulch, destroy or cover leaf piles after the maple has dropped all of it's leaves to help prevent re infestation the next growing season.
Fungicides are not usually recommended to treat tar spot.