Maple Trunk Sunscald with Lichens: Borer Prevention and Wound Management

10-year-old maple with 24" tall southwest-facing trunk damage, white "barnacles" (lichens), and callus formation—classic sunscald with secondary lichen colonization, requiring borer prevention and vigor promotion.

Diagnosis: Sunscald, Not Frost Crack

• Southwest exposure + Oklahoma hot summers = sunscald
• Callus ridges forming = tree actively compartmentalizing (good sign)
• Damage occurred previously (callus takes months/years)
• Lichens on dead wood = normal colonization, not harmful

Sunscald vs. Frost Crack

Frost cracks: Sudden winter splitting, loud cracks, reopen annually. Sunscald: Gradual bark death from freeze-thaw cycles on sun-warmed bark. Your tree's southwest face, callus formation, and climate confirm sunscald.

Management Protocol

1. Borer Prevention (Critical)

• Spray wound area with imidacloprid (Merit/Bayer Advanced) NOW
• Repeat early spring and mid-summer
• Borers target stressed trees—this wound is entry portal

2. Promote Compartmentalization

• Fertilize: 10-10-10 at 1 lb per inch trunk diameter, scattered, watered in
• Repeat early spring
• Water deeply during drought (1" weekly)
• Mulch 3" to dripline, not touching trunk

3. Wound Care

• DO NOT paint/seal wound—traps moisture
• Leave loose bark—will slough naturally
• Protect callus ridges—don't damage living edges
• No wrap needed now (wound is old)

Decay Fungi Reality

Internal decay fungi cannot be treated with fungicides. Strategy: outgrow decay via vigor. Tree will eventually wall off decay if healthy. Hollowing takes decades; callus closure eliminates problem.

Prognosis

Good. Tree is actively healing. With borer protection and vigor management, it will likely close the wound fully and live decades more.