Borer Infestation: Trunk Spray with Onyx or Merit to Save Tree

Borer Infestation: Trunk Spray with Onyx or Merit to Save Tree

Holes with sawdust at the base, audible chewing, and bee-like insects entering/exiting indicate borers (or bark beetles on conifers). Foliage still green means the tree can be saved if treated immediately.

Emergency Treatment

• Spray trunk from ground to maximum reach with Onyx (dinotefuran) or Merit (imidacloprid).
• Solution must run down bark to penetrate entry holes.
• If insect population is too high, tree may still die—but worth the attempt.
• If foliage is browning throughout, chance of success is very low.

Act now; borers kill quickly once they girdle the cambium.