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Borer Control in Sunset Maple: Insecticides and Tree Vigor

Bark splitting with symmetrical round holes on a sunset maple indicates borer infestation. Borers target stressed trees, so improving vigor is as important as insecticide treatment.

Treatment Options

Trunk spray: Permethrin (Hi-Yield 38 Plus, Astro) applied monthly May-August kills hatchling larvae before they bore in.
Systemic: Imidacloprid (Merit, Bayer Tree & Shrub) or dinotefuran (Onyx) applied as soil drench or trunk spray moves into the wood to kill feeding larvae.
Fertilization: Apply 10-10-10 at 1 lb per inch of trunk diameter in fall and spring to boost tree health.

Bark Care

Remove loose bark around holes to expose larvae to predators and sprays. Do not use pruning paint—it slows healing.

Plant Diseases: Japanese Maple Scale Infestation: Simple WD-40 and Oil Treatment; Identifying Lichen vs. Disease on Maple Trunks and Managing Frost Cracks; Troubleshooting a Struggling Sunset Maple: Water, Nutrients, and Herbicide Risks; Maple Trunk Bark Peeling: Wound Care (Bark Scoring); Cottony Maple Scale: Systemic Imidacloprid Best for Large Trees; Maple Leaf Galls: Harmless Cosmetic Issue; Maple Tree Decline: Moss, Bark Loss, and Mushrooms Signal Aging, Not Just Disease; Sunset Maple Dieback: Winter Damage Unlikely, Borers or Environment Suspected; Peach Tree Borer Fatality in Mature Plum Tree; Japanese Maple Tree Diseases: Identification and Treatment

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Sunset Maple Bark Splitting: Normal or Problem?

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