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Bark Peeling on Mature Japanese Maple: Sunscald or Something Else?

Likely Cause: Sunscald

Bark shedding all around the lower trunk of a 20-year-old Japanese maple (Acer palmatum) in spring suggests sunscald—a winter injury where thawing/refreezing ruptures bark cells. Common on thin-barked trees like maple.

Management

Do not wrap now; wrapping is a fall preventive measure.
Protect from borers: Spray trunk with insecticide containing imidacloprid (e.g., Merit) to prevent borer entry through cracks.
Fertilize: Apply 10-10-10 at 1 lb per inch trunk diameter, scattered to drip line, water in well.
Monitor: The tree may compartmentalize the wound. Avoid further stress.

Sunscald damage is usually not fatal if the tree is otherwise healthy.

Plant Diseases: Japanese Red Maple Post-Transplant Leaf Spots: Need Photo; Red Maple Bark Splitting: Frost Cracks, Lichens, and Decline Risk; Diagnosing Browning Leaves on a Japanese Dwarf Red Maple; Phyllosticta Leaf Spot on Japanese Maple: Cosmetic Late-Season Fungus; New Japanese Maple Brown Leaf Spots: Phyllosticta Leaf Spot; Red Tip Photinia Entomosporium Leaf Spot: Preventive Fungicide Program; Japanese Maple Leaf Scorch: Heat, Wind, and Root Moisture; Japanese Maple Leaf Spots: Phyllosticta (Purple Eye); Japanese Maple Leaf Spots: Phyllosticta Fungus — Mostly Cosmetic; Japanese Red Maple Trees: Varieties, Climate, and Care

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