Borer Infestation in Young Maple Trees: Diagnosis and Control

Borer Infestation in Young Maple Trees: Diagnosis and Control

Two-year-old maples (12 ft tall, 4-inch diameter) with splitting bark, scarred tissue underneath, tiny bugs in wounds, and blotchy bark are likely infested with borers—beetle larvae that tunnel under bark, disrupting vascular flow.

Immediate Treatment

• Spray wounded trunk areas with Merit (imidacloprid) or other borer-labeled insecticide.
• Apply as a bark drench to penetrate entry holes.

Supportive Care

• Water deeply: 1 inch per week (measure with a pan under sprinkler).
• Mulch 3 inches deep with organic material; keep away from trunk.
• Avoid fertilizing until tree recovers.

Prevention

• Protect trunks from mechanical injury (mowers, trimmers).
• Wrap young trunks in winter to prevent sunscald cracks that attract borers.
• Monitor annually for new holes or frass.

Early treatment saves trees; advanced infestations may require removal.