Crimson King Maple with White Leaf Coating: Powdery Mildew

White Film on Maple Leaves? Powdery Mildew Is the Culprit

A Crimson King maple with white/gray powdery coating on leaves, especially southern exposure, browning edges, and leaf curl has powdery mildew. Common in humid, shaded, or poorly ventilated sites.

Control

• Fungicides: Triadimefon (Bayleton), triforine (Funginex), thiophanate-methyl (Cleary's 3336), propiconazole (Banner).
• Organic: Sulfur, potassium bicarbonate, neem oil.
• Timing: Start at first sign; spray both leaf surfaces every 7–10 days.
• Cultural: Improve air flow, avoid overhead water, reduce shade if possible.

Outlook

Powdery mildew is rarely fatal but weakens the tree and reduces aesthetics. Consistent management keeps it in check.