Newly planted 'October Glory' maple develops round brown spots after heavy rain.
Phyllosticta leaf spot (Phyllosticta minima). Common on Amur, Japanese, red, silver maples. Spots: circular, tan with purple-red borders; later, black fruiting bodies in rings.
Late-season infection causes minimal damage—maybe early leaf drop. Fungicides rarely needed. If desired, spring spray with mancozeb or chlorothalonil prevents new spots but won't cure existing ones.
Check local nursery for tree fungicide. Large trees hard to spray; damage is cosmetic. Rake fallen leaves.
Expert insight provided by Steve.
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