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Synanthedon exitiosa

Written by: 

Jaime Pinero

Overview

PTB attacks all stone fruits, particularly peach and nectarine. Female moths are dark blue with a broad orange band around the body and forewings darker than the clear hind wings. The male is smaller and has three to four narrow yellowish bands across the body; both pairs of wings are clear. 

PTB larvae burrow into the bark, usually entering at a crack or wound near the soil surface. Larvae feed on the cambium and tunnel between the inner bark and the sapwood. Larvae normally attack the tree trunk between 7.5 cm (3 in) below ground to 25 cm (10 in) above ground; larger roots are occasionally attacked. Areas attacked often have masses of gum, mixed with frass, exuding from the bark. Young trees may be completely girdled and eventually die; older trees are debilitated and more susceptible to other insects or diseases.

Biology

PTB has a single generation per year. PTB overwinter as partially grown larvae, in a gallery under the bark - usually close to or below ground level. Most larvae complete their development during June and July. Most adults emerge and mate, and females oviposit, during July and August on tree trunks, in cracks or under bark scales, and in soil near the tree trunk.

Monitoring

Pheromone traps can be used to monitor PTB. Captures peaking at less than 10 moths per week generally indicates low pest pressure. Also, inspect the base of the tree for gum containing frass and sawdust. 

Management

Mating disruption. The Isomate PTB Dual mating disruption pheromone dispensers release pheromones for 100 to 120 days and should be placed in the orchard before moth emergence in early June. For effective control of this pest, use at least 200 dispensers per acre, distributed uniformly throughout the entire block. The Isomate PTB Dual dispensers will also control LPTB, but they need to be placed in the orchard earlier in the spring before adult LPTB emergence. 

Insecticides. Recommended treatments include root dips for new plantings and sprays targeting the lower 18 to 24 inches of the trunk. Roots should be dipped in an insecticide solution before planting. Protective trunk sprays with products containing chlorpyrifos should be applied in the summer from the lower scaffold branches to the soil line.

Peachtree borer - Synanthedon exitiosa (photo: Eugene E. Nelson, Bugwood.org)
Peachtree borer - Synanthedon exitiosa (photo: Eugene E. Nelson, Bugwood.org)
Peachtree borer - Synanthedon exitiosa (photo: Joseph Berger, Bugwood.org)
Peachtree borer - Synanthedon exitiosa (photo: Joseph Berger, Bugwood.org)
Peachtree borer larva - S. exitiosa (photo: Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org)
Peachtree borer larva - S. exitiosa (photo: Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org)
Peachtree borer pupa (photo: J.A. Davidson, Univ. Md, College Pk, Bugwood.org)
Peachtree borer pupa (photo: J.A. Davidson, Univ. Md, College Pk, Bugwood.org)