ANKENY, Iowa –  For many Iowa farmers, the damage done by sudden death syndrome (SDS) in 2010 is all too fresh a memory.
“In 2010 we had the perfect weather conditions for an SDS outbreak,” says Iowa State University (ISU) Plant Pathologist Leonor Leandro. “There has been a gradual buildup of the SDS pathogen in Iowa soils over the past 10 years, and the unique weather conditions in 2010 were ideal for severe disease development.”
Regarding the outlook for SDS in 2011, Leandro says, it all depends on the weather. “If we get a dry year, we will not see SDS. But after last year, SDS is near the top of farmers’ list of challenges to manage.”
Iowa Soybean Association (ISA) Director of Contract Research David Wright says, “The best management tactic for SDS is to select varieties with resistance to SDS, especially since there are no seed treatments or fungicides that we know will manage the disease.”
A new publication, Sudden Death Syndrome-Resistant Soybean Varieties for Iowa – PM 3009, has been produced by ISU and ISA and is now available to the public. The publication lists more than 300 commercial soybean varieties resistant to SDS in maturity groups I, II and III.
“The soybean varieties in the publication were submitted by seed companies and fall into the top several categories of SDS-resistant varieties available from those companies,” ISU Extension Pathologist Daren Mueller says. He notes that the information provided by seed companies has not been verified by ISU. Companies’ ratings vary, so not all “resistant” lines are equal. ISU does not guarantee or endorse any specific varieties listed.
In addition to listing resistant varieties, the publication also reviews other factors to consider in the selection process.
“Yield potential is an essential consideration in the decision process,” Mueller says. “A variety may have high resistance ratings and low yield potential. It is important to select the best resistant varieties with the highest yield potential to ensure maximum soybean production in the fall.”
Resistance to other pests should also be considered. “Because soybean cyst nematode may increase SDS severity, varieties with resistance to both SDS and SCN should be selected,” Leandro says. “And in another growing season, conditions may be right for other diseases so it is important to select varieties with resistance to several diseases.”
The publication is available as a downloadable PDF from ISU Extension’s online store at or from ISA’s Production Research Library at Or a print copy may be obtained by calling 800-383-1423.