Maple Leaf Spots in the Catskills: Harmless Cosmetic Issue

Diagnosis

"Measles" on maple leaf undersides in late June are almost certainly either fungal leaf spots (e.g., Phyllosticta, Septoria) or eriophyid mite galls. Both are common, weather-dependent, and rarely threaten tree health.

Why Not to Worry

• Established trees tolerate partial defoliation without long-term harm.
• Spots appear after leaves have done most of their photosynthetic work for the season.
• Populations fluctuate wildly year to year; next spring may be spot-free.

Management (If Desired)

Fungicides (chlorothalonil, mancozeb) or miticides must be applied preventively at bud break—impractical for forest trees. For landscape specimens, rake and destroy fallen leaves to reduce inoculum. Otherwise, simply enjoy the forest diversity.