Sap Leaking at Cottonwood Base: Likely Borer Damage

Wet Spot on Cottonwood Trunk = Borer Activity

Sap oozing at the base of your 20-foot cottonwood signals borers—larvae of moths or beetles tunneling under bark. They attack stressed trees (drought, compaction, injury). The wet area means they’re active.

Control Steps

• Spray the affected trunk area with Merit or Onyx (systemic bark-penetrating insecticides).
• Non-chemical option: insert a flexible wire into entry holes to impale larvae.
• Fertilize to reduce stress: 10-10-10 at 1 lb per inch trunk diameter, scattered and watered in (before rain).

Healthy trees resist borers; address the underlying stress.