By Greg Tylka, Iowa State University
There are hundreds of soybean varieties with resistance to the soybean cyst nematode (SCN). An updated list of SCN-resistant varieties in maturity groups 0, 1, 2, and 3 for 2021 was published as Iowa State Extension publication PM 1649 in November 2020 and is available here.
Of the 849 varieties in the publication, 810 have resistance genes from the same genetic source, a breeding line called PI 88788. Resistance genes from PI 88788 have been used in the vast majority of varieties for most of the last 30 years (see figure in ICM News article here). Continuous use of soybean varieties with this single source of resistance has led to SCN populations developing increased reproduction on varieties with the PI 88788 resistance throughout Iowa and the Midwest.
Increase Soybean Yields with SCN Resistance Other Than PI 88788
Growing soybean varieties with a source of SCN resistance other than PI 88788 can increase yields as a result of better nematode control. For example, soybean varieties with the Peking source of SCN resistance yielded 22 bushels per acre more than varieties with PI 88788 SCN resistance in an experiment conducted by ISU in southeast Iowa in 2019. The increased yields correlated with much better control of SCN reproduction. End-of-season SCN egg densities with Peking varieties averaged 800 eggs per 100 cm3 of soil whereas egg densities with PI 88788 varieties averaged 14,400 eggs per 100 cm3 (see ICM News article here).
It is critical that farmers begin growing soybean varieties with SCN resistance different from PI 88788 in SCN-infested fields. These varieties should be grown in rotation with varieties with PI 88788 resistance, not as a complete substitute for PI 88788 resistance. Below is information about soybean varieties for Iowa with SCN resistance from sources different from PI 88788.
Varieties with SCN resistance from Peking and other sources
The soybean varieties in the table below have the Peking source of SCN resistance. The information in the table was provided by the seed companies offering the varieties. Brands are listed alphabetically and varieties are listed in increasing order of maturity within brand.
Table. Soybean varieties in maturity groups 1, 2, and 3 with the Peking source of SCN resistance available for use in Iowa.
University of Minnesota IPM Specialist Bruce Potter compiled a list of soybean varieties in maturity groups 1 and 2 with Peking SCN resistance; the list is available online here.
Additional soybean varieties with SCN resistance different from PI 88788 and Peking include:
- Golden Harvest brand GH2329X - resistance from PI 89772, relative maturity 2.3.
- IAR2601SCN from Iowa State University - resistance from PI 38489B, in maturity group 2.
- IAR2801SCN from Iowa State University - resistance from PI 437654, in maturity group 2.
- NK brand S23-G5X - resistance from PI 89772, relative maturity 2.3.
Additional information about the soybean varieties mentioned in this article and many other SCN-resistant soybean varieties is available online here.
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