The first pyrethroid resistant soybean aphids were reported in Minnesota in 2015. Since then, pyrethroid resistant soybean aphids have been reported in Iowa, North Dakota, and South Dakota. In an effort to address resistance, researchers from those states have put together a new extension publication. The publication highlights areas where pyrethroid resistance has been reported, and it provides management recommendations for reducing issues associated with resistance.
A few of the key strategies that are listed for managing pyrethroid resistant soybean aphids include:
- Apply insecticides only when they are needed. Scout soybean and apply insecticides at the economic threshold of 250 aphids/plant.
- Apply insecticides correctly (i.e., use the proper rates, good coverage, etc.) and check the efficacy of the insecticides that were applied 3-5 days after the application occurred.
- If additional insecticide treatments are necessary, alternate insecticide groups to reduce selection pressure.
Tables have been included in the publication to assist with the rotation of insecticides and to provide a list of what products are currently labeled for soybean aphid management.
The new publication titled Management of Insecticide-Resistant Soybean Aphids is currently available online.
Because of the soybean aphid’s lifecycle and ability to travel long distances in the winged form, it is possible that pyrethroid resistant soybean aphid populations will be observed in additional areas in the coming years.
A list of insecticides approved for use in South Dakota soybean is available in the current Soybean Pest Management Guide.