Birch Trees Oozing Red Discharge: Bronze Birch Borer

Two 25-year-old birches ooze red discharge from under bark. Owner fears loss.

Diagnosis: Bronze Birch Borer

• Larvae tunnel in cambium, girdling trunk/limbs.
• Red sap accumulates above tunnels; bark shows swollen ridges.
• D-shaped exit holes; one generation/year.
• Stressed trees (drought, injury) most susceptible.

Treatment

• Spray trunk with Merit (imidacloprid) to point of runoff.
• Or soil drench with Bayer Tree & Shrub Insect Control (same active).
• Systemic works better on flatheaded borers (like bronze birch borer).
• Check cambium viability—if girdled fully, tree may die.

Act quickly; consult nursery for products.