Plum, Prune (Fresh): Peach twig borer
Photo by: K. Grey
Biology
The peach twig borer attacks both shoots and fruit. In the spring, overwintering larvae bore down the center of shoots, causing the tip to wilt or “flag”. Each caterpillar can damage several shoots.
Later generations of larvae feed on both shoots and fruit. They often burrow into the stem end of young fruit. Pits of infested fruit are often split, with the larvae inside. They may also feed on the fruit surface.
The caterpillars are reddish-brown with black heads and yellowish rings on the body. Mature caterpillars are up to 1⁄2″ long. The adult moth is dark gray and about 1⁄3″ long.
Apricot, nectarine, and peach may also be attacked. The peach twig borer can be an important pest of peaches, particularly in eastern Washington.
Management Options
See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.
Non-chemical Management
Select non-chemical management options as your first choice!
- Cut out flagging twigs below mined portion. Be sure to kill larvae inside.
- A tiny wasp parasitizes eggs of the peach twig borer. Avoid use of broad-spectrum insecticides whenever possible to conserve beneficial insects.
- Overwintering larvae may be found under thin bark in branch crotches. Look for a buildup of chewed bark and frass (excrement).
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply products at bud swell and/or at complete petal fall when later-season larvae bore into twigs, etc.
- Homeowners should not make foliar applications to trees over 10 ft. tall.
- Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.
Approved Pesticides
If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.
Additional Image
Photo by: M. Bush
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Evidence of noncompliance may be reported through your local Extension office.