On-farm evaluation of aphid-resistant soybeans

Host plant resistance for soybean aphid is a management tool to protect yield. Our lab has evaluated the efficacy and of host plant resistance but generally with small plot research. Working with Iowan farmers, we evaluated the efficacy of aphid-resistant soybean on commercial farms in Iowa. With funding from the North Central Region – Sustainable Agriculture Research and Education Program, we are studying the potential for aphid-resistant soybeans on a larger scale. We provided farmers with experimental and commercially available soybean varieties containing a 2-gene pyramid (Rag1+2). Our farmer cooperators allowed us to scout these fields for aphids throughout the summer; we compared seasonal aphid pressure and yield in 2017 and 2018. Despite low aphid populations in both years, we still observed a significant difference between susceptible and resistant varieties. Regardless of the genetic background, pyramided varieties had significantly lower aphid populations. There was no difference in yield between the resistant and susceptible varieties, suggesting there is no “yield drag” when soybean have host plant resistance genes.

What does it mean for farmers: Commercially-available, aphid-resistant soybean had fewer aphids than susceptible varieties with no yield drag associated with the Rag1+Rag2 gene combination. The use of host plant resistance greatly reduces the likelihood of needing foliar insecticides and will help improve profit margins.

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