Results of SDS Variety Trials

Trait selection. When selecting a soybean variety to plant there are many traits in addition to yield potential that may be important to consider. Producers focus on planting soybean varieties with different disease resistance traits depending upon pathogen and disease prevalence in their region.

Genetic resistance is a "must have" for yield-robbing pathogens such as the soybean cyst nematode that occur widely throughout the Midwest. Conversely, genetic resistance to other pathogens, particularly those that cause disease and associated yield loss very infrequently in certain growing regions, may not be a priority for producers and/or may be unavailable for purchase. Examples would be traits for frog eye leaf spot in Group I soybeans or traits for white mold in Group IV soybeans. This is because in certain years the pathogen that causes frog eye leaf spot is more likely to cause yield losses in regions that have warm, humid growing seasons (more typical in the regions that grow group IV soybeans), while the pathogen that causes white mold is more likely to cause yield losses in regions that have cool, wet weather during early flowering (more typical in regions that grow group I soybeans).

Sudden death syndrome.
Although sudden death syndrome and the pathogen that causes it were first described in Arkansas in 1971, reports and confirmed instances of this disease have since occurred throughout most of the major soybean producing states in the Midwest with it only first appearing in a widespread nature in Minnesota and Wisconsin in 2002 and 2006.

As the range of this disease has increased, so has the need for genetic resistance in soybean varieties. Many seed companies do provide basic information about the relative susceptibility of their varieties to sudden death syndrome. There is, however, a need for unbiased, third-party information about variety susceptibility. This is essential to compare susceptibility among varieties from different seed companies.

2014 Variety Trial Results. In 2014, the relative susceptibility/resistance to sudden death syndrome was assessed by researchers from both Iowa State University and Southern Illinois University through funding by the United Soybean Board. Through a series of variety trials at multiple locations throughout Illinois and Iowa, close to 500 varieties from 19 different seed companies (spanning maturity groups I through V) were screened at one or more maturity group-appropriate location(s) in each state. Based on their reaction relative to a known susceptible check variety, varieties were then place into one of four different categories: Susceptible (S), Moderately Susceptible (MS), Moderately Resistant (MR) or Resistant (R).

This data can be a valuable resource to have on hand during variety selection decisions, and may be particularly sought after by those producers that sustained large sudden death syndrome-associated yield losses in 2014.