Host plant resistance for soybean aphid is the newest management tool for farmers who need to control this insect pest in their bean fields. In 2010, a single gene expression, called Rag1, was commercially released in a soybean variety in the North Central Region of the United States—which includes Iowa. Aphids feeding on soybean plants that have the Rag1 do not live as long or produce as many offspring compared to aphids that are feeding on susceptible soybean plants. In small plot evaluations of the Rag1 gene, there is a dramatic decrease in the seasonal accumulation of soybean aphid compared to susceptible soybean varieties.
Iowa State University recently released a new publication, Soybean aphid-resistant varieties for Iowa, listing the currently available soybean seed that has resistance to soybean aphid. Following is an explanation of how to use these varieties and how they may fit on your farm, according to ISU Extension entomologist Erin Hodgson, and research entomologists Mike McCarville and Matt O'Neal.
New ISU publication lists soybean varieties available having aphid resistance
The list of varieties in the publication is intended to assist farmers who want to adopt this new management tactic for control of soybean aphids, a sporadic pest that can reduce yield by as much as 40%. The listing includes soybean 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:
* Four varieties with resistance to both the soybean aphid and soybean cyst nematode. SCN is a pervasive and serious pest of soybeans in Iowa. Farmers with SCN infested fields are encouraged to select an SCN-resistant variety to plant.
* 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 whether or not to plant soybean aphid-resistant varieties on your farm. 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 new soybean aphid publication that lists the varieties available and offers recommendations on using them was funded in part by the soybean checkoff and the Iowa Soybean Association.