Greg Tylka, Department of Plant Pathology and Microbiology
Growing soybean varieties with resistance to the soybean cyst nematode (SCN) is an excellent way to manage this pervasive and serious soybean pest. Growers have hundreds of SCN-resistant soybean varieties from which to pick.
To help Iowa growers sort through all of the possibilities, Iowa State University Extension personnel annually compile a list of SCN-resistant soybean varieties in late maturity group 0 and maturity groups 1, 2, and 3 in ISU Extension publication PM 1649, "Soybean cyst nematode-resistant soybean varieties for Iowa." This work is supported by soybean checkoff funds from the Iowa Soybean Association.
The annual list of SCN-resistant soybean varieties has just been updated with information about varieties available for the 2012 growing season. Information in the publication is organized by maturity group and company and includes the relative maturity, herbicide resistance, iron deficiency chlorosis tolerance rating and source of SCN resistance of the varieties (see figure 1).
There are 807 varieties in the updated publication, which is only six fewer than last year's record high number of 813 varieties (see figure 2). The varieties are from 42 companies, Iowa State University and the University of Missouri. There are 151 varieties in late maturity group 0/group 1, 346 varieties in maturity group 2, and 310 varieties in maturity group 3. Almost all of the varieties possess SCN resistance from the PI88788 breeding line (also called the source of resistance). Most of the varieties are glyphosate resistant, nearly 10 percent are LibertyLink® and several varieties, including all of those from Iowa State University, have no herbicide resistance.
In total, there are 21 SCN-resistant soybean varieties listed in the publication that were developed by Iowa State University scientists, all with soybean checkoff funding from the Iowa Soybean Association. Two of the varieties contain unique sources of SCN resistance. Variety "IAR2101 SCN" (maturity group 2) has SCN resistance from PI88788 in combination with PI507354, and variety "IAR3001 Phyto SCN" (maturity group 3) has SCN resistance from PI438489B and PI90363.
Iowa State University's management recommendations for SCN are online in a downloadable format, Soybean Cyst Nematode (SCN) Management Recommendations, IPM 63. Additional information about the biology, scouting and management of SCN can be found at www.soybeancystnematode.info. And results of evaluation of SCN-resistant soybean varieties at numerous locations throughout Iowa can be found at www.isuscntrials.info.
Greg Tylka is a professor of plant pathology with extension and research responsibilities in management of plant-parasitic nematodes.
Figure 1. Iowa State University's annual list of SCN-resistant soybean varieties includes company contact information, variety brand and names, relative maturity, herbicide resistance, iron chlorosis tolerance, and source of SCN resistance.
Figure 2. The number of SCN-resistant soybean varieties in late maturity group 0 and maturity groups 1, 2, and 3 for Iowa growers since 1991. The red portion of each bar represents the number of varieties with resistance from a source other than PI88788 resistance.