The peachtree borer is often the most destructive insect attacking mature peach trees. The injury is often minimized or overlooked, particularly in orchards in which weeds and grass are permitted to grow around tree trunks. Plums are attacked less frequently, but sometimes are damaged by this insect. The larval stage causes the damage by boring into the trunk near the ground line. Infested trees decline in vigor and may die as a result of damage inflicted by the borer larvae.

How To Determine the Presence of Peachtree Borers

To determine if a peach tree is infested with borers, inspect the trunk at the soil line. Large masses of gum which contain brown sawdust-like material is an indication that peachtree borers are present. Take a sharp instrument, such as a pocket knife, and probe under the bark to see what is causing this gum-like material to appear. If peachtree borers are the cause, a dirty white larvae just under the bark may be found. The presence of this gum-like material does not always indicate that borers are attacking a tree. The bleeding can be caused by sun scald, disease, machine damage, or other types of insects attacking the tree.

When to Check for Peachtree Borers

The adults, which are clear-winged moths resembling wasps in general appearance, are abundant from the middle of May to early October. Eggs are laid on the trunks of the trees and hatch in about ten days into tiny larvae which burrow directly into the wood and feed intermittently throughout the winter.

Beginning in early April, the mature larvae spin flimsy cocoons covered with fragments of dark sawdust. The larvae change to dark brown pupae which can be found near the ground line at the base of the tree. There is a single generation each year. Therefore, you can look for evidence of the peachtree borer damage during the spring or summer months. If the trees have not been treated, inspecting the tree throughout the year at any time will give you an indication that peachtree borers may be present.

Peachtree Borer Control

Commercial Orchards

Commercial peach growers should treat infested trees in late August to early September. Treat with a recommended product and thoroughly treat all bark areas from ground level to scaffold limbs.

Backyard Orchards

Homeowners can control peachtree borers by two methods. One is by spraying the trunks with lindane endosulfan (Thiodan®), or chlorpyrifos (Dursban® 2E). Mix according to label directions. When using these sprays, treat the lower trunk and around base of tree, soaking bark and wetting trunk from crotch to ground. Do not apply to fruit or foliage. This treatment method is best if applied in August or September when there is no fruit on the tree.

The borers can also be controlled by applying paradichlorobenzene (PDB) crystals around the base of the tree during the period of October 20 to November 15. PDB crystals should be applied when the soil is dry and the air temperature is 55F or above. Weeds should be removed from around the base of the tree and the soil leveled one foot from the tree trunk. Place the crystals in a narrow groove encircling the tree about two inches from the tree trunk. Care should be taken to keep any of the crystals from coming in contact with the tree. Clean soil should be placed over the crystals so as to form a cone-shaped pile about six to eight inches high around the base of the tree. The soil should be removed from around the base of the tree in late March or early April. The amount of PDB crystals to be used is determined by the age and size of the tree. For two and three-year-old trees, use 1/2 ounce; for four to five-year-old trees, use 3/4 ounce; and for mature trees, use one ounce. Refer to product label for proper application.

Will Moth Balls Work?

There are PDB crystals specifically labeled for peachtree borer control. These should be used and moth balls not substituted for this purpose. Do not use crystals containing napthalene.

INSECTICIDE CONTROL SUGGESTIONS

Insecticide	Rate Per Gallon	Rate Per 100 Gallons
Chlorpyrifos
Dursban 2E)	2 fl oz or 4 Tbsp	----
(Dursban 4E)	1 fl oz or 2 Tbsp	----
(Lorsban 4E)	1 fl oz or 2 Tbsp	3 qts
Endosulfan
(Thiodan 3E)	1/3 fl oz or 2/3 Tbsp	1 qt
Lindane	1/2 fl oz or 1 Tbsp
Esfenvalerate
(Asana XL)	----	2.0 - 5.8 fl oz

NOTE: 1 fl oz = 2 Tbsp

JVR 3/98

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Last modified: June 23, 1998 by Andrew Perrone