How to Treat Sunscald on Young Red Maple Trees

Dan wrote in about his Red Sunset Maple suffering from significant bark damage where the bark has completely separated from the sapwood. He peeled back the loose bark months ago to prevent insect infestation, but the exposed wood shows cracks and hasn't improved. The tree appears healthy otherwise, with no leaf or bud issues.

Diagnosis: Sunscald Injury

This is a classic case of sunscald, which commonly affects young maples. Sunscald occurs in late winter when bright sun—especially reflecting off snow—warms the thin bark on the south or southwest side of the trunk. The living bark tissue becomes active, then freezes rapidly when temperatures plummet at night, killing the inner bark. Young maples with thin bark are particularly vulnerable.

Treatment and Prevention

Unfortunately, once bark splits, there's little you can do to reverse the damage. However, you can support the tree's natural healing process:

• Remove loose bark carefully: Trim away only the bark that's already detached, cutting back to where it's firmly attached. This speeds healing and reduces hiding spots for borers.
• Protect against borers: Apply an insecticide containing imidacloprid (often sold as Merit) to the wound area to prevent borer entry.
• Prevent future sunscald: Wrap the trunk with burlap, kraft paper, or commercial tree wrap from late fall through early spring. Alternatively, shade the south and west sides with boards or screens.

Long-Term Care

Keep the tree well-watered during dry periods and avoid late-season fertilization, which can promote tender growth susceptible to winter injury. With proper care, young maples typically recover well from sunscald, forming callus tissue over the wound over several seasons.