Treating Borer Damage and Sap Flow in Crimson Maple

Diagnosis

A 6–7 inch wound oozing brown, pus-like sap on an old crimson maple indicates borer infestation. Borers target stressed trees, so the wound is likely a secondary symptom.

Recommended Actions

1. Insecticide treatment: Spray the wound area with a borer-specific product such as Merit (imidacloprid) or Onyx (bifenthrin) to kill larvae under the bark.
2. Improve tree vigor: Fertilize with 10-10-10 at 1 lb per inch of trunk diameter, scattered around the drip line and watered in deeply.
3. Monitor: Keep the tree well-watered during dry periods to reduce stress.

Do not apply wound paint; it can trap moisture and hinder natural compartmentalization.