Maple Leaf Spot: Phyllosticta—Mostly Cosmetic

Your 3-year-old maple has black spots on leaves in summer. Likely Phyllosticta leaf spot (fungal).

Characteristics

No treatment needed for tree health.
Rake/destroy fallen leaves to reduce spores next year.
If desired, preventative spring fungicide (mancozeb, chlorothalonil) at bud break—but rarely worth it on small trees.

Phyllosticta looks bad but doesn’t hurt the tree. Rake leaves in fall; enjoy the maple.

Trees: Maple Tree Multiple Spot Syndrome: Insect, Fungus, and Algae Complex; Managing Leaf Spots on Quaking Aspens: Cultural Practices Over Home Remedies; Brown Spots on Maple Leaves: Phyllosticta Leaf Spot; Maple Tar Spot and Crown Thinning: Management and Tree Vigor; Maple Leaf Spots: Phyllosticta and Tar Spot; Maple Leaf Spots: Phyllosticta—Rake Leaves, Don't Spray; Japanese Maple Cold Damage: Will Leaves Return?; Maple Leaf Spot: Phyllosticta Diagnosis and Management; Bigleaf Maple Aphid Identification and Management; Silver Maple Leaf Drop: Maple Petiole Borer, Not Disease

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