Flowering Plum Peachtree Borer: Comprehensive Pest Management Guide

Linda in Arizona: flowering plum with sap seeping from multiple trunk areas. Suspects borers. Lost same species last year despite painting trunk.

Expert Identification

Peachtree borer (Synanthedon exitiosa)—major pest of peaches, also attacks cherry, plum, apricot, nectarine, ornamental shrubs.

Damage Mechanism

Larvae feed on cambium/inner bark at trunk base (few inches above to 6 inches below ground). Girdles young trees; weakens older trees for secondary pests/diseases. Frass in gum indicates borers; clear gum = disease/environmental injury.

Control Options

• Commercial insecticides: Permethrin (Pounce, Ambush), esfenvalerate (Asana), carbaryl (Sevin)
• Newer option: Onyx (sprayed on lower trunk, absorbed, kills borers)
• PDB moth crystals: Fumigant applied at base (specific rates by tree age, precautions required)
• Mechanical: Dig out larvae or puncture with wire (risk of additional injury)

Cultural Prevention

• Fertilize 10-10-10 at 1 lb per inch trunk diameter
• Water during dry spells
• Healthy trees resist borers better

Key Insight

Painting trunk (previous advice) is ineffective. Targeted insecticide timing + tree health management is the proven approach for this destructive pest.