Quick Facts
- Black raised spots on leaf surfaces
- Yellow halos around spots
- Spots enlarge through the growing season
- Premature leaf drop in severe cases
What Is Tar Spot?
Tar spot is a common foliar disease caused by fungi in the genus Rhytisma, most commonly Rhytisma acerinum. It affects maples throughout the Atlanta area, including red maples, southern sugar maples, and Japanese maples. Despite its alarming appearance, tar spot is a purely cosmetic disease that does not harm tree health. The raised, black, tar-like spots on leaves are one of the most frequently asked-about tree conditions in metro Atlanta, especially in late summer and fall when they become highly visible.
How to Identify Tar Spot
Tar spot is one of the easiest tree diseases to recognize:
- Black raised spots: Thick, glossy black spots — ranging from small dots to blotches over an inch in diameter — develop on the upper surface of maple leaves. They are raised above the leaf surface and have a distinct, tar-like texture.
- Late-season timing: Spots first appear as pale yellow-green areas in early to mid-summer, then darken to their characteristic black by late summer and fall.
- Progressive increase: The number and size of spots increase as the season progresses. By autumn, heavily affected leaves may be covered with numerous spots.
- Minor leaf drop: In years with heavy infection, some premature leaf drop may occur, but this is rarely significant enough to affect tree health.
Treatment & Management
No treatment is necessary. Tar spot does not damage trees and fungicide applications are not recommended:
- Do NOT apply fungicides: Spraying fungicides for tar spot is wasteful and environmentally irresponsible. The disease causes no meaningful harm and chemical treatment is unnecessary.
- Rake and remove fallen leaves: The fungus overwinters on infected fallen leaves. Raking and composting (or disposing of) maple leaves in autumn reduces the spore load for the following year.
- Improve air circulation: Pruning to open the canopy and improve airflow can modestly reduce infection severity by helping leaves dry faster after rain.
- Accept the cosmetic imperfection: Tar spot is a natural part of maple ecology in the southeast. Healthy, well-maintained maples tolerate it without any decline.
When to Call an Arborist
Tar spot itself does not require professional intervention. However, if your maple shows signs of actual decline — such as significant branch dieback, sparse foliage, or poor growth — those symptoms are not caused by tar spot and warrant an evaluation by an ISA-certified arborist. EastLake Tree Services can determine whether underlying health issues need attention through a plant health care assessment. Call 404-850-1174 or request a free quote.