By Josie Borlongan, Garden Guides Contributor
About Peachtree Borers
The peachtree borer (Synanthedon exitiosa) feeds under the bark of peach trees and has been one of the most serious problems of peachtree orchard owners and home gardeners. The peachtree borer also attacks stonefruits and almonds.
The adult peachtree borer is a steel-blue to black moth that emerges in the late spring and late summer. Female peachtree borers lay their eggs on the bark at the base of the tree trunks during summer. The larvae that are hatched can get deeper into the bark, reaching the crown of the tree as they burrow deeper and causing considerable damage to the trees.
Prevention and Control
Examine your trees yearly especially during the fall season. Remove 6 to 8 in. of soil from around the trunk and peel back the bark to observe the burrows. Pheromone traps can be used to detect peachtree borers in the orchard.
Once detected, remove peachtree borers by a process called worming, whereby the soil is removed from around the base of the infected trees and a pocketknife or any pointed instrument is used to dig out the larvae.
You can also fumigate the bark by placing para-dichlorobenzene (PDB) crystals on the soil around the base of the tree and mounding soil up around the trunk for three to six weeks in September.
Damage is found primarily in the crown area or lower part of the trunk just above or just below the soil line. Peachtree borers can girdle and kill a healthy young tree. They have been known to attack older trees causing little damage.
Parasitic nematodes (Steinernema carpocapsae), Ants, Spiders, Lacewings
Ants, spiders, and lacewings prey on larvae in exposed locations, and birds feed on larvae and adults. These natural enemies are not capable of adequately controlling borers.
Applying parasitic nematodes into borer tunnels with a squeeze bottle applicator while the peachtree borer larvae are feeding most actively and the tunnels are largest, usually in mid- to late summer.
Other Methods of Control
* Behavioral Control: Disrupting the mating to prevent the spread of the peachtree borer is done by hanging small dispensers filled with peachtree borer pheromone that bears the scent of the borer's sex attractant in the orchard. The inability of the male moths to locate the female moths will prevent mating, which prevents fertile eggs from being laid.
* Chemical Control: Lindane or multipurpose orchard pesticide may be used, and some brands of chlorpyrifos (Dursban), endosulfan and carbaryl (Sevin) can be used for home plantings. Apply insecticides to the bark using a paint brush or a hand sprayer.