Maple Sunscald and Limb Loss: Causes and Preventive Care

Natural Shedding vs. Sunscald Injury

Lower limb loss on a 20-30 year old maple is normal—shaded branches self-prune. The vertical, dark, moist crack from ground to 8 feet is sunscald: winter freeze-thaw cycles on the south/west trunk rupture living bark cells.

Why It Matters

Sunscald wounds are entry points for fungi and borers. Young, thin-barked maples are especially vulnerable.

Protective Measures

• Spray the crack with Merit (imidacloprid) to deter borers.
• Fertilize with 10-10-10 at 1 lb per inch of trunk diameter (scatter, water in).
• Do not paint or wrap the crack—let it dry and compartmentalize naturally.

Beyond borer prevention, the tree should compartmentalize the wound over time.