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Coral Bark Japanese Maple Borer Infestation: Treatment Options

Symptom Analysis

3-year-old coral bark Japanese maple in sunny location oozing brown sap from trunk ~1 foot above ground. Indicates borer infestation—thin maple bark easily damaged, triggering sap flow.

First: Rule Out Mechanical Damage

Check for weed-eater/string trimmer injury at base
Prevent future damage: 3-inch organic mulch ring (not against trunk)
Mulch retains moisture, eliminates need for close trimming

Borer Control Options

Option 1: Merit (Imidacloprid) Spray

Apply to wound area and trunk
Absorbed by bark, kills borers inside

Option 2: Bayer Advanced Tree & Shrub Insect Control (Soil Drench)

Apply to soil around tree
Roots translocate to trunk, limbs, leaves
Longer protection, easier application
Product link: Bayer Advanced Concentrate

Recommendation

Soil drench (Option 2) preferred for systemic, season-long protection with single application. Maintain mulch ring to prevent recurrence.

Plant Diseases: Japanese Maple Honeydew and Sooty Mold: Aphid or Scale Infestation; Orange Fungus at Base of Japanese Maple: Mulch Decay, Not Tree Disease; Saving a Large Japanese Maple with Bark Loss and Dead Branches; Coral Bark Japanese Maple Trunk Discoloration: Cold Injury; Japanese Maple Bark Loss at Base: Borer Treatment and Vigor Boost; Maple Tree Oozing White Foam: Bacterial Wetwood (Slime Flux); Coral Bark Maple Winter Kill: Scrape Test for Life; Can You Split a Multi-Trunk Coral Bark Japanese Maple?; Japanese Maple 'Coral Bark': Brilliant Winter Bark and Golden Fall Foliage; Coral Bark Maple Identification

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