After this run of heat, you may be noticing leaves prematurely falling from your maple tree. If the edges are brown and curled, your tree is experiencing leaf scorch due to the hot, dry conditions. If you are noticing dark spots on the leaves, however, it’s a fungus called Maple Tar Spot.
Maple Tar Spot affects several Northeast Ohio maple trees, including Black Maple, Red Maple, Silver Maple, Sugar Maple, and Boxelder. As the name suggests, the fungus causes marks to appear on the leaves that look like splattered spots of tar. As the fungus matures the spot develops a yellow ring around it. When the damage to the affected leaves becomes too severe, they fall.
The good news is the condition is not fatal to the tree, as the fungus does not cause any systemic damage, but tree enthusiasts agree it is unattractive. Unfortunately, it also is difficult to prevent because the fungus is dormant in the winter, harboring in fallen leaves and other debris where it reawakens to infect trees year after year.
Like other fungi, Maple Tar Spot recurs in the spring as spores that are released and carried by wind and rain to the young leaves of nearby trees. The tiny yellow spots that initially appear on leaves are easy to miss. When the tree begins to drop damaged leaves later in the summer, the fungus remains, lying in wait until the following spring.
One of the most effective ways to control Maple Tar Spot is to rake and gather the fallen leaves as quickly as possible and dispose of them before the fungus can find a place to harbor. Do not use them in compost because the heat generated in a home composting system is usually not hot enough to kill the fungus.
You may also talk to your arborist about fungicide sprays. Applied at the appropriate time in the spring, sprays can be effective limiting Maple Tar Spot provided it is applied thoroughly over the entire tree. Eradicating the fungus completely is a challenge partly because reaching every leaf on a large tree is difficult and because trees frequently become infected from nearby trees that haven’t been treated. Also, the spray is ineffective if it is applied too early or too late in the fungi’s life cycle.
If you believe your maple tree is infected with Maple Tar Spot or you have questions about the overall health of any of your trees, contact the experts at GP Tree. Check out all of GP Tree’s services, from tree care to tree removal.
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