How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

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.

DAMAGE
Peachtree borers can girdle and kill young trees. Older trees can withstand the damage unless there are many larvae or the tree is attacked several years in a row.

MANAGEMENT

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.

• Summary of Important Links

Common name		Amount to Use**		R.E.I.+	P.H.I.+
(trade name)		(conc.)	(dilute)	(hours)	(days)
When choosing a pesticide, consider information relating to the impact on natural enemies and honey bees and environmental impact.
A.	ESFENVALERATE*
	(Asana) XL	4.8–14.5 fl oz	2–5.8 fl oz	12	14
	MODE OF ACTION GROUP NUMBER1: 3
	COMMENTS: Apply as a directed trunk and scaffold limb spray. Thorough coverage of trunk and scaffolds is required.
	**  For concentrate applications, use the amount given in 80-100 gal water/acre or lower if the label allows; for dilute application, amount is per 100 gal water to be applied in 300-400 gal water/acre, according to label. + Restricted entry interval (R.E.I.) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Preharvest interval (P.H.I.) is the number of days from treatment to harvest. In some cases the REI exceeds the PHI. The longer of two intervals is the minimum time that must elapse before harvest. * Permit required from county agricultural commissioner for purchase or use. 1 Rotate chemicals with a different mode-of-action Group number, and do not use products with the same mode-of-action Group number more than twice per season to help prevent development of resistance. For example, the organophosphates have a Group number of 1B; chemicals with a 1B Group number should be alternated with chemicals that have a Group number other than 1B. Mode of action Group numbers are assigned by IRAC (Insecticide Resistance Action Committee). For additional information, see their Web site at http://www.irac-online.org/.

IMPORTANT LINKS

• Photos of borer damage

Back to management

PUBLICATION

UC IPM Pest Management Guidelines: Apricot
UC ANR Publication 3433
Insects and Mites
W. W. Coates, UC Cooperative Extension, San Benito County
R. A. Van Steenwyk, Insect Biology, UC Berkeley
W. J. Bentley, UC IPM Program, Kearney Agricultural Center, Parlier
K. R. Day, UC Cooperative Extension, Tulare County
K. A. Kelley, UC Cooperative Extension, Stanislaus County
J. L. Caprile, UC Cooperative Extension, Contra Costa County
Acknowledgment for contributions to Insects and Mites:
L. C. Hendricks, UC Cooperative Extension, Merced County

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