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Late Season Fruit Pests

Late Season Fruit Pests

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This archived news story is available only for your personal, non-commercial use. Information in the story may be outdated or superseded by additional information. Reading or replaying the story in its archived form does not constitute a republication of the story.

Larry Sagers Horticultural Specialist Utah State University Extension Service Thanksgiving Point Office © All Rights Reserved

Fruit pest update

BOXELDER BUGS: Peach, apple, and pear growers should keep an eye out for adult and nymphal populations of boxelder bugs. Significant populations have been spotted on peaches in Perry (Boxelder County). Aggregations of the adults were observed within the tree canopy. Adults can feed on leaf veins, petioles, fruit, and shoots.

In Logan, nymphal boxelder bugs in riparian areas were observed, suggesting that there will likely be substantial feeding as the nymphs try to grow and mature into adulthood by winter (boxelder bugs overwinter as adults). If excessive numbers are seen in peach, apple, or pear orchards, it may be wise to apply a material with a short pre-harvest interval, such as Sevin (carbaryl, PHI: 3 days), or malathion (PHI: 7 days).

PEACH TWIG BORER: Unharvested peaches are highly desirable feeding sites for twig borer caterpillars at this time of year. Most of the trees' shoots have set terminal buds and hardened off by now, forcing the young larvae to look to the fruit, which have ripened and become more appealing.

Examine the fruit for signs of feeding damage (especially around the stem end, although the young caterpillars can burrow in anywhere). If the twig borer has been feeding, you should see tiny brown grains (frass) as well as some dry, crystallized "sap," and maybe a darkened area where fungus has also colonized the tissue.

Trap catches have risen recently in Boxelder, Davis, and Utah Counties. Genola, Payson, Kaysville, Spanish Fork, and various locations in between may need to be treated sometime this weekend or early next week, IF there is a significant moth population and the fruit will be on the tree for more than another week. Cache Valley growers may need to treat later in the week.

CODLING MOTH: According to Diane Alston, "the rule of thumb" for late-season codling moth control is to maintain protection through the second week of September. Most growers likely treated in mid- to late-August, so depending on your harvest date, another treatment may be necessary next week to protect your crop through harvest.

As always, be sure there is sufficient time to accommodate the PHI of the material used. Many moths continue to be caught, especially in Boxelder county. Continue monitoring your fruit and traps.

Many people are discovering some interesting pests as they are picking their fruit. If you are among them read on.

Many people are concerned about the brown spots on the leaves of their apples and pears. These slightly raised velvety spots are caused by a tiny eriophyd mite called a blister mite.

Eriophyd mites are different from spider mites. They are much smaller and have a cylindrical shape. Because they are so small it is impossible to see them without the aid of a microscope.

Although the leaf spotting looks bad and visually causes a great deal of concern, the actual damage is minimal. Thee mite do not respond to insecticidal treatments nor do they respond to most miticides.

The best control is to use a dormant oil spray in the early spring. This oil spray smothers the creatures by plugging up their breathing holes. There is nothing that can or should be done now.

If the pear leaves and fruits look a little strange, they also have a pest problem. Russet mites also cause the skin of pears and some apple varieties to turn brown and woody. Once this happens, it is to late for effective controls. Once again use the dormant spray in the early spring.

Earwigs are a problem in peaches particularly if they are damaged. Split pits are common because of the hot weather early in the season. There is nothing to do about the split pits but you can try to keep the earwigs out of the peaches.

Earwigs crawl up and down the tree and usually spend the nighttimes in the soil debris. Spray the trunks with Tanglefoot. This sticky material is the material they use to coat flypaper. It will trap the earwigs as they try to crawl back up to the top of the tree. Spraying them is usually not effective and you must observe all preharvest intervals.

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