Tar Spot
Seeing black spots on your maple leaves can seem a bit disappointing especially when you’re really looking forward to the reds and oranges that autumn brings. These spots are called “tar spots” and they are a minor disease common on maple trees. Tar spot shows up as a yellow spot on leaves in early summer and slowly become dark black by mid to late summer. This disease only affects leaves and not the rest of the tree, thus it is primarily a cosmetic issue.
Trees that are prone to Tar Spot include Norway Maples, Silver Maples, Boxelder Trees, and Willow Trees
How to Identify Maple Tar Spot
Early Signs:
● ~⅛ inch yellow spots on leaves in early summer
Late Signs:
- ~¾ inch black spots on leaves in mid to late summer
Maple Tar Spot Prevention
For Homeowners:
- Maple tree tar spot spreads through the air from leaf litter
- Rake up and dispose of fallen leaves to help prevent the spread of tar spot
- Maintain the vigor of your maple trees
Maple Tar Spot Prevention
For Professionals:
- Properly diagnose the issue
- Apply preventive fungicides as appropriate
Tree Tar Spot Treatment
Tree Tar Spot FAQ
Will Tar Spot kill my maple tree?
No, tar spot only affects the leaves, not the entire tree. Because of this, the health and integrity of the tree is rarely affected by tar spot.
Will tar spot return in the spring?
Tar spot is spread from the wind. If there are leftover spores from the previous year’s affected foliage, your tree can be infected year after year. This is why it is a good idea to thoroughly dispose of leaves in the fall.