Answer: Maples are subject to a variety of foliar problems, so it would be difficult to diagnose it without a sample to look at. The drought was so tough on plants that many showed unusual foliage symptoms due to stress and in their weaker state were also more likely to be attacked by other things such as bacterial problems. I would suggest cleaning up the leaves from the tree this fall and then keeping an eye on it next spring and summer. If the spots reappear, take a sample and perhaps a photo or two of the tree to your county extension and/or to consult with professional nursery staff to see if they can identify it specifically. If the tree is a large and valuable specimen, it might also be worth having it evaluated by a professionally trained, certified and licensed arborist with a specialty in ornamental trees. In many cases nothing really needs to be done, especially when a problem develops late in the season when the foliage has pretty much served its purpose and done its job for the growing season. In a few other cases it might require timely attention. Without knowing exactly what is causing the spots however, it is impossible to tell you specifically. I hope it is nothing too serious.
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