Plum, Prune (Fresh): Peach twig borer

categories: Plum, Prune (fresh) Plum, Prune (Fresh) Insects Tree Fruits

revision date: 2022-12-05 12:00

Peach twig borer caterpillar.
Peach twig borer caterpillar
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

Use Integrated Pest Management (IPM) for successful plant problem management.

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: Visit Home and Garden Fact Sheets for more information on using pesticides.

  • 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

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.

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