Resistant soybean varieties are extremely important for managing soybean cyst nematode (SCN). Effective resistant varieties produce good yields and suppress nematode reproduction.
Almost all SCN-resistant soybean varieties are developed from a breeding line named PI 88788. These varieties contain 7 to 10 copies of a single resistance gene. Varieties with more copies of the resistance gene suppress SCN reproduction to a greater extent than varieties with fewer copies of the gene. Greater suppression of SCN reproduction leads to lower end-of-season SCN numbers and less yield loss caused by the nematode.
The ISU SCN-resistant Variety Trial Program
The number of copies of the SCN resistance gene in commercial soybean varieties is not known or not reported, and the amount of SCN control provided by resistant soybean varieties varies significantly.
Hundreds of commercially available resistant varieties are evaluated for yield and SCN control each year in the ISU SCN-resistant Variety Trial Program. The work is funded by the soybean checkoff through the Iowa Soybean Association. Field experiments (such as shown below) are conducted in farmers’ fields, one in each of the nine crop-reporting districts in Iowa.
Results are published in ISU Extension and Outreach publication IPM 52. Printed copies of the report are sent to 48,000 Iowa households and businesses as an insert in the Iowa Farmer Today newspaper annually in January.
Former ISU Ph.D. student, Seungki Lee, and his advisor, ISU Distinguished Professor of agricultural economics, GianCarlo Moschini, conducted a study of the value of the information produced in the ISU SCN-resistant Soybean Variety Trial Program and ISU Extension publication IPM 52. Lee and Moschini also estimated the worth of the SCN-resistant soybean varieties to farmers and to the seed industry. The results of their research were published in a paper titled “On the value of innovation and extension information: SCN-resistant soybean varieties” in the January 2022 issue of the American Journal of Agricultural Economics. Lee and Moschini used data from 2011 to 2016 from Iowa and northern Illinois, the geographies where the ISU variety trial reports were distributed in those years.
The researchers concluded that the economic welfare of farmers who used the information from the ISU SCN-resistant Variety Trial Program was increased by as much as $205 million from 2011 to 2016. Additional information about all of the research findings can be found in the journal paper online.
Getting the Most Out of SCN-resistant Varieties
Growing effective SCN-resistant soybean varieties allows farmers to produce profitable yields in infested fields while keeping SCN numbers in check. Variety selection is a critical decision because the level of SCN control varies greatly among the hundreds of SCN-resistant varieties. The results of the research conducted by ISU agricultural economists underscore the large financial gains that farmers can realize by selecting and growing resistant soybean varieties that yield well and also provide effective control of SCN. The ISU SCN-resistant Variety Trial Program provides information to assist farmers in the variety selection process.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on February 28, 2022. The information contained within may not be the most current and accurate depending on when it is accessed.