Host-plant resistance for soybean aphid is the newest management tool for farmers. In 2010, a single gene expression, called Rag1, was commercially released in the north-central region. Aphids feeding on Rag1 plants do not live as long or produce as many offspring compared to feeding on susceptible plants. In small plot evaluations of the Rag1 gene, there is a dramatic decrease in the seasonal accumulation of soybean aphid compared to susceptible varieties.

The entomology department at Iowa State University recently released a new publication, Soybean aphid-resistant varieties for Iowa, that lists currently available soybean seed with resistance to soybean aphid. The list is intended to assist farmers wanting to adopt this new management tactic for soybean aphids, a sporadic pest that can reduce yield by as much as 40%. The listing includes varieties in late maturity group 0 and maturity groups 1, 2 and 3. 

The list contains 16 varieties from 10 companies. Seed companies provided varietal information including relative maturity, herbicide resistance, source of aphid resistance and resistance to other pests. Two items of interest to farmers will be:

  1. Four varieties with resistance to both the soybean aphid and soybean cyst nematode (SCN).  The SCN is a pervasive and serious pest of soybean in Iowa. Farmers with SCN-infested fields are encouraged to select an SCN-resistant variety.
  2. One variety carrying two different genes for soybean aphid resistance. Varieties containing two soybean aphid resistance genes provide significantly better aphid control than varieties containing a single resistance gene.

The publication also contains Iowa State University recommendations for considering soybean aphid-resistant varieties. For more information on soybean aphid management consult: Soybean Aphid Management Field Guide 2nd edition. Additional information about insecticides is found in the most recent soybean aphid insecticide efficacy evaluation. This publication was funded in part by the Soybean Checkoff and the Iowa Soybean Association.