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Linden Borer at Base of 40-Year Tree: Trunk Spray Treatment

Pest ID

Small holes at base + sawdust mounds + insects entering/exiting = Linden Borer (Saperda vestita). Larvae tunnel near root crown, weakening trunk—tree can snap in wind.

Urgent Treatment

Spray trunk base (as high as possible) with Onyx (bifenthrin) or Merit (imidacloprid). Products soak into bark, kill larvae in galleries.

Vigor Support

Fertilize with 10-10-10 at 1 lb/inch trunk diameter (scatter, water in). Stress invites borers; health deters them.

Reference: UMN Linden Borer Factsheet

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