Plum and prune-Peachtree borer

Synanthedon exitiosa

Pest description and crop damage The adult male is a steel-blue, clear-winged moth. The female is similar in appearance, but has smoky-colored wings and an orange band around her abdomen. Adult flight is usually from late June through September and eggs are laid at, or on, the base of the fruit tree. Larvae burrow in the crown and roots, girdle young trees, and weaken others. A single larva can girdle a newly-planted fruit tree. Larval presence can best be detected by globs of gum mixed with a granular brown frass (excrement) that appear at the base of infested fruit trees. Full-grown larvae are 1 to 1.5 inch long with a whitish body and a brown head.

Management-cultural control

Protect the base of the fruit tree from larval entry by placing a plastic or metal cone or barrier around it before egg laying begins. The cone should be pushed 1 to 2 inches into the soil and should fit snugly around the trunk at the top to prevent the tiny larvae from getting beneath it. Alternatively, if there are only one or a few peach trees in a home orchard, it may be quicker and cheaper to control this insect by "worming." Use a pocket knife, wire or some pointed instrument to remove dirt around the tree and dig out the larvae.

Management-chemical control

Spray applications, and more importantly pesticide residues, on the trunk of the tree can prevent newly-hatched larvae from boring beneath the tree bark and entering the woody trunk where they are protected from all insecticide sprays.

Management-chemical control: HOME USE

  • azadirachtin (neem oil)-Some formulations are OMRI-listed for organic use.
  • gamma-cyhalothrin-Highly toxic to bees.
  • kaolin-Applied as a spray to leaves, stems, and fruit, it acts as a repellant to some insect pests. Some formulations are OMRI-listed for organic use.
  • lambda-cyhalothrin-Highly toxic to bees.
  • pyrethrin-Highly toxic to bees. Some formulations are OMRI-listed for organic use.
  • zeta-cypermethrin-Highly toxic to bees.

Management-chemical control: COMMERCIAL USE

Spring and summer sprays

  • esfenvalerate (Asana XL) at 4.8 to 14.5 fl oz/A. REI 12 hr. PHI 14 days. Extremely toxic to fish and aquatic invertebrates; avoid spray drift and runoff to surface waters.
  • lambda-cyhalothrin (Warrior II) at 1.28 to 2.56 fl oz/A. REI 24 hr. PHI 14 days. May disrupt beneficial mite populations. Extremely toxic to fish; avoid spray drift and surface runoff.
  • Isomate P at 100 to 250 dispensers/A. These dispensers release a synthetic insect pheromone that disrupts moth mating. Dispensers must be placed in the orchard before adult mating and egg-laying flight begins in late June or when the first moths are captured in pheromone traps. Careful scouting and monitoring are necessary to use this product effectively.