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Keep a Constant Eye on Codling Moth

June 25, 2021
codling moth on wood

Source: Clemson University – USDA Cooperative Extension Slide Series, Bugwood.org

Codling moth can be a nuisance year-round in walnuts. But the worst damage usually occurs early in the season as temperatures rise. The sooner it gets warm, the more generations that can follow. Control out of the gate goes a long way toward effective, year-long management of codling moth.

The first flight of codling moth took place this spring from the overwintered generation. But its 2 peaks, 1A and 1B, can last several weeks as moths lay first-generation eggs. According to the University of California Integrated Pest Management Program, adult moths can emerge as late as the end of June in the Central Valley and into early July in the state’s coastal areas. Monitoring for infestation and damage can help growers make treatment decisions.

First-generation sprays, including use of Proclaim® insecticide, have been made in many locations already and are a good first step in managing the more destructive worms and offering some activity on adults. Proclaim is a Group 6 chemistry, which makes it a solid resistance management partner for other insecticides used later in the season on codling moth. Proclaim also does not wipe out beneficial insects that are present at the same time as codling moth in walnuts.

Second and third generation codling moth will start to emerge in June. The key to in-season control is to know what other economically damaging pests are present so you can treat for all of them. Using any 1 product class too long will allow codling moth to develop tolerance to it.

Good options are to switch to Minecto Pro® or Besiege® insecticides.

If you are battling mites or navel orangeworm (NOW), Minecto Pro is a wise choice. Walnut acres have exploded in recent years with better irrigation options on marginal land, which has spurred movement of NOW into walnuts. Broad-spectrum Minecto Pro offers active ingredients, cyantraniliprole and abamectin, that are Group 28 and Group 6 insecticides respectively.

For walnut husk fly and NOW control, Besiege has 2 active ingredients that combat both insects, along with codling moth adults. Chlorantraniliprole and lambda-cyhalothrin, fall into Group 28 and Group 3 categories. Besiege has outstanding knockdown and long-lasting residual.

Now is the time to keep a close eye on codling moth. Assess how your sprays are working and look ahead to next season. Chances are you will see a third and even fourth generation into fall that will move into tree trunks and debris to overwinter, ready to strike in 2022.

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