Resistant pests cause farmers excessive stress and costly crop losses each year. Rotating modes of action maximizes insect control and minimizes resistance development, improving growers’ bottom lines.
“Many insect pests have a high propensity to develop resistance, including the diamondback moth — one of the most difficult pests to control and one of the most important pests when it comes to resistance management. They are adept at surviving, making them the most problematic pests over numerous crops and multiple generations,” says Shine Taylor, North America Biology Leader Insecticides, Corteva Agriscience™, Agriculture Division of DowDuPont.
How to Employ Rotation to Avoid Resistance
Before each season, growers should review their integrated pest management program to ensure they are rotating out of the previously used mode of action. Switching between brand names may not be enough — many brands use the same mode of action, potentially increasing resistance development. For example, multiple insecticide sprays of a singular mode of action, such as diamide, can limit control, both now and in future years, due to resistance development.
Spinetoram, the unique active ingredient in Delegate® WG insecticide, is alone in a chemical class (Group 5), making it essential to resistance management. Targeting pests by contact and ingestion, Delegate quickly knocks down insects, saving growers costly nonstop spraying.
Even if producers know the active ingredient of a product, reading the label to determine the Insecticide Resistance Action Committee (IRAC) class of insecticide ensures the mode of action is being rotated, Taylor says.
“Trade names make things very complicated for growers, consultants and retailers because the mode of action isn’t always easily discernible,” he says. “This is especially true for diamide-containing insecticides, which may be sold under several different trade names, all with different mixtures and multiple active ingredients.”
Taylor points to the IRAC website as an exhaustive reference to learn about modes of action for resistance management planning.
“Diamides are classified a Group 28 insecticide, and it’s important to avoid using another Group 28 product during that application window or season based on your resistance management strategy. In comparison, Delegate WG insecticide is a Group 5 insecticide. Ideally, growers should rotate between not just trade names but also modes of action,” Taylor says.
Additionally, insecticide premixes that include two modes of action can affect resistance management plans.
“Target pests with the mode of action required for control, because spraying unnecessary products could speed up resistance development,” he says. “With a premixed product, you may only need one of the active ingredients and could potentially be flaring another pest with the second active ingredient. It is also important to remember that while some products improve control when mixed together, you are using up multiple modes of action in one treatment.”
Continuously rotating modes of action minimizes resistance development.
“Resistance development can ultimately cause manufacturers to pull a product from the market, and we could potentially lose that active ingredient from our arsenal. We might even lose efficacy to neighboring chemistries if cross-resistance develops,” he says. “Rotating modes of action avoids selectively breeding a pest population with tolerance or resistance that carries over to multiple generations.”
Delegate offers growers an ideal partner in season-long insect control programs. Delegate has a novel mode of action for fast knockdown and lasting control of a broad spectrum of destructive pests, such as Oriental fruit moth, leafminers, numerous worms, leafrollers, thrips and spotted wing drosophila.
“Rotating Delegate, with spinetoram as an active ingredient, with another product containing another mode of action, lengthens the efficacy of each mode of action over the long term,” Taylor says.
Delegate® WG insecticide has a short four-hour re-entry interval and is easy on beneficial insects. When applied according to the label, Delegate is nondisruptive to beneficials, doesn’t harm lady beetles or lacewings, and does not flare mites.
“Sometimes it takes some additional planning at the beginning of the year to prepare your season-long resistance management program. Do that math. Choosing the optimum chemistry for each stage of the growing season will leave you additional modes of action in your toolbox,” Taylor says.
Besides rotating modes of action, scouting your fields regularly will alert you to unsavory visitors and the need for timely additional treatments.
To learn more about how Delegate can help keep orchards free of yield-robbing pests, visit:
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