Tar Spot
Natural History
Tar spot on maple | Photo credit: Steven Katovich, USDA Forest Service, Bugwood.org
Tar spot is caused by species of fungi in the genus Rhytisma. Tar spot gets its name from the characteristic black, tar-like spots that develop on infected leaves. The disease can occur on numerous tree hosts, but is most common on willow, maple, and holly.
In Florida, the disease occurs in summer, as leaves are infected by spores released from infected leaves from the previous year. No control is necessary as the disease, although striking, is only cosmetic and does not affect health of trees.