Borer Damage and Decay in Autumn Blaze Maple

Three-year-old Autumn Blaze maple shows bark cracking, insect activity, and thinning canopy. Planting damage at base noted. Seven neighboring trees healthy.

Diagnosis: Borer Entry via Planting Wound

Installer-caused bark injury created entry for borers. Decay fungi also colonized the wound. Borers kill young maples; decay hollows trunks over decades but rarely causes death.

Action Plan

• Borer control: Spray trunk with Onyx or Merit. Alternatively, soil-drench Bayer Advanced Tree & Shrub Insect Control (imidacloprid) for season-long systemic protection.
• Wound care: Remove loose bark to promote callusing. Do not apply sealant.
• Vigor improvement: Fertilize with 10-10-10 at 1 lb per inch trunk diameter in fall and spring.
• Monitor neighbors: Check for boring dust, single holes, wet bark—treat only if found.

Stress from the original wound enabled the attack. Boosting health reduces future vulnerability.