Black spots oak leaves

[Dana]

I was at my father-in-law's over thanksgiving and he asked me why his fallen white oak leaves had a blackish mildew like spot on them. The spot is about the size of a pencil eraser and on the majority of the leaves. He said he had never seen anything like that on them before. Is it just mildew from a rainy fall or something worse?

[Sylvus]

Probably anthracnose or some equally innocuous leaf disease.  In the fall, especially, these leaf diseases are a non-issue as far as tree health is concerned.  Interesting, though. Of course, in Michigan the leaves have been dead for a couple months.  If the black spots occurred after the fall change, the black spots could be many things, none of them of any consequence, except to the curious mycologist.  

[SwampDonkey]

I'll second that motion.