Problem Identifier Unit Screen//v.w/ RR Template

Problem Identifier Unit Screen//v.w/ RR Template Peach Twig Borer

Problem
New growth at the tips of the twigs wilts and dies. When the affected twigs are sliced open lengthwise, worms about ½ inch long are found inside. The reddish brown color of these worm distinguishes them from Oriental fruit moth worms, which cause similar damage. Later in the season, some of the maturing fruit when cut open are also found to contain these worms. During the summer, there may be cocoons attached to the branches or tree crotches.

Analysis
(Anarsia lineatella)

This borer attacks all of the stone fruits, and is particularly damaging along the Pacific Coast. The young larvae hibernate during the winter in burrows under loose bark or in other protected places on the tree. When the tree blooms in the spring, the larvae emerge and bore into the young buds, shoots, and tender twigs, causing twig and leaf death. When mature, they leave the twigs and pupate in cocoons attached to branches. After several weeks, gray moths emerge and lay eggs on the twigs, leaves, and fruit. Egg laying and larval damage can occur all through the growing season. Later in the summer, larvae feed almost exclusively on the maturing fruit. In addition to ruining the fruit, these pests may cause abnormal branching patterns on young trees.

Solution
Worms in the twigs and fruit cannot be killed with pesticides. To prevent future worm damage, kill the moths by spraying infested trees with a fungicide containing captan or carbaryl according to label directions. Next spring, spray again just before the blossoms open. Repeat the treatment 2 more times at intervals of 10 to 14 days.

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