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The problem is caused by one of a couple of fungal infections that have gotten a boost from the wet weather this year according to the BDN. It is widespread, and at this point, nothing can be done about it. The infected trees look terrible, but it doesn't cause any long-term harm. There are 2 fungi out there that cause this problems: tar leaf spot and anthracnose according to the Maine Forest Service.
If you would like to learn more check the article at BDN:
Photo Credit: Art MacKay