Answer: It is extremely difficult to diagnose a plant problem without seeing it but I will venture an educated guess. Tar Spot. Tar spot is caused by a fungus. It will not kill your trees, but it is unsightly and can cause early leaf drop before the fall season.
The spots first appear as small yellow spots in June, then progress to black spots on the leaves which can be 1/8 inch in diameter to an inch or more. The spots can also appear on the seeds (samaras).
The fungus winters-over on leaves that have dropped to the ground. If the leaves are not raked up in the fall, the spores will reappear in the spring on the old leaves and spread to any nearby tree. Treating the trees is usually not effective since the spores can travel from a neighbor's tree onto your trees.
If your tree has these spots, which then turn into curling leaves in mid-July, you may have a different disease, Anthracnose.
Wait and watch, and be sure to rake up fallen leaves.
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