Soybean Insecticide Choices – 2020
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I know that commodity prices are a major concern and spending more money on more expensive products seems inefficient, but we have enough data to know that we have widespread resistance to pyrethroids with corn earworm. Spraying a product with limited control makes very little sense either.
We have a number of effective insecticides for corn earworm in North Carolina soybeans. One of these is the insecticide chlorantraniliprole, which an active ingredient in Coragen, Prevathon, and Besiege. Because we are entirely reliant on this insecticide to control corn earworm (bollworm) in Bollgard II, WideStrike, and TwinLink cotton and Coragen is used in tobacco, Dominic and Anders are encouraging growers to avoid this insecticide in soybeans. In addition, soybean looper is resistant to this insecticide and generally shows up in the biggest numbers a few weeks after earworms.
Therefore growers should use products like Blackhawk, Intrepid Edge, or Steward to control corn earworms in soybeans. These products will pick up most of the soybean worm complex.
Our online threshold calculator for corn earworm in podding beans can be found by visiting the Soybeans portal, clicking on Insect Management, then Thresholds, and scrolling down to the online corn earworm in soybean threshold calculator link. Earworm management is critical once there are pods on the plant.
Defoliation Applications Prior to and After Bloom:
Our official defoliation threshold is 30% defoliation throughout the canopy until bloom or two weeks prior to bloom (depending on how the crop looks) and 15% defoliation after bloom. Here is a good guide to estimating soybean leaf defoliation.
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