Soybean cyst nematode is effectively managed by planting resistant soybean varieties that are grown in rotation with corn, and Iowa growers have hundreds of SCN-resistant soybean varieties from which to choose.
Iowa State University Extension in October 2011 has updated its list of SCN-resistant soybean varieties in late maturity group 0 and maturity groups 1, 2, and 3. These are the soybean maturity groups suitable for planting in Iowa. "This information is helpful for growers when they are deciding which soybean varieties to plant in 2012," says Greg Tylka, ISU Extension nematologist and plant pathologist, who oversees the preparation of this annual publication.
"Growing soybean varieties with resistance to the soybean cyst nematode is an excellent way to manage this pervasive and serious soybean pest," says Tylka. "Growers have hundreds of SCN-resistant soybean varieties from which to pick."
To help Iowa growers sort through all of the possibilities, ISU Extension personnel annually compile a list of SCN-resistant soybean varieties in late maturity group 0 and in maturity groups 1, 2, and 3. The information is then made available 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.
Know your choices, hundreds of SCN-resistant varieties available for Iowa
This list of SCN-resistant soybean varieties has been updated with information about varieties available for the 2012 growing season, notes Tylka. Information in the publication is organized by maturity group and by seed 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 the late maturity group which is group 0 and group 1 maturity beans. There are 346 varieties listed in maturity group 2, and 310 varieties in maturity group 3. Almost all of the varieties possess SCN resistance from the PI88788 breeding line. This information in the publication tells you the "source of resistance" to SCN that the beans have.
What about herbicide resistance? Soybean growers are interested in this information because most growers today make their soybean variety choice compatible with their weed control program, notes Tylka. Most of the soybean varieties listed in this publication are glyphosate resistant, nearly 10% are LibertyLink soybeans and several of the varieties listed, including all of those from Iowa State University, have no herbicide resistance.
Follow management recommendations to control soybean cyst nematode
In total, there are 21 SCN-resistant soybean varieties listed in the publication that were developed by ISU 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.
ISU'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.