09/21/2026
Tar spot is caused by a fungus and sticks to all maples, but mainly Norway, red and silver.
The fungus overwinters in the black, tarry spots on fallen leaves, then releases spores each spring that drift onto the young leaves and start the cycle again.
The good news: severe infections (the kind that caused leaves to drop early) are extremely rare. Mostly, tar spot is a cosmetic issue that does not threatens a tree’s health. Since the fungus spreads from last year‘s leaf litter, raking up and disposing of fallen leaves each autumn can reduce the chance of re-infection the next spring.