Coral Bark Maple Losing Bark: Sunscald, Borers, or Natural Exfoliation?

Diagnosing Bark Loss on a Coral Bark Maple

A coral bark maple is shedding bark at the base, forming a pedicle-like edge at the peeling margins. The foliage and branches look healthy. The owner has applied an anti-borer product and wonders about the cause and treatment frequency.

Possible Causes

• Sunscald (southwest injury): Common on young, thin-barked maples. Winter sun warms the bark, activating cells that then freeze at night, killing tissue. Usually on the south or southwest side.
• Borers: Attack stressed trees. Look for boring dust or holes.
• Natural exfoliation: Some maples shed bark as they mature.

Management

• Sunscald prevention: Wrap trunks with burlap, kraft paper, or commercial tree wrap in fall; remove in March.
• Borers: If evidence appears, spray wound area with imidacloprid (Merit). Fertilize with 10-10-10 at 1 lb per inch of trunk diameter to boost vigor.
• General care: Keep the tree well-watered and mulched. Avoid wound dressings.

When to Worry

If the canopy remains full and green, the tree is likely fine. Monitor for progressive dieback or insect activity.