How to Manage Pests
UC Pest Management Guidelines
Peachtree borer eggs are laid during the summer on the bark at the base of trees. Larvae overwinter in the tree trunk near the soil line. They feed in the crown area and burrow up into the tree. At maturity, a larva is about 1-inch long, and has a light-colored body and a dark head. In late spring, larvae pupate near the entrance of their burrows or in the soil. Adults emerge from May through September; they are steel blue to black clearwing moths with a 1-inch wing span.
Look for the presence of frass and gum at the bases of trees when monitoring orchards in spring. Also check trees in fall for signs of peachtree borer activity. At this time, you can kill larvae by carefully using a knife or wire to probe the trunk. Mark infested trees that you find, and return to treat them the following spring with insecticide by spraying the trunk from the scaffold to the soil line. Apply the insecticide with a hand-held sprayer to the tree trunk from the juncture of the main scaffold limbs to the soil line. Cover the trunk thoroughly, using enough spray material so it will run off to form a small puddle at the base of the tree. Use from 0.5 to 1.5 gallons per tree, depending upon the size of the trunk. Remove suckers and pull soil away from the base of the tree before treating. Two applications are recommended to protect during the prolonged period when adults are active, one in mid-May when adults are first detected and one in the middle of July. Be careful to observe preharvest intervals and use low-pressure sprays to avoid contaminating fruit.
You can use pheromone traps to monitor adult emergence. They are useful for determining the presence of peachtree borers. (The pheromone lure may be listed as peachtree borer or greater peachtree borer.) Place the traps in trees no later than late April and maintain them through September, changing lures at the recommended interval (usually one month) and the trap bottoms when they become dirty and lose stickiness. If they catch large numbers of male peachtree borers (approximately 10 or more per week), return later and examine the trees carefully for signs of feeding activity. Be sure to properly identify the moths that are trapped; other clearwing moths may be attracted by the peachtree borer pheromone.
Keep tree bases free of vegetation to help reduce problems with peachtree borer, especially in the Central Valley. Heat and dryness reduce the survival of eggs and larvae.
UC IPM Pest Management Guidelines: Apricot