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.
Affected Plants
Almonds
Apricots
Cherries
Nectarines
Peachtree
Plums
Damage
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.
Predator Insects
Parasitic nematodes (Steinernema carpocapsae), Ants, Spiders,
Lacewings
Natural Insecticides
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.
