Resistance to SDS has been reported in both field and greenhouse experiments, however, most commercial cultivars are still considered susceptible to the disease. A key goal of this project was to discover new sources of resistance to SDS through the evaluation of 10,144 plant introductions from the USDA Soybean Germplasm Collection. Lines with the highest level of resistance were identified and made available to other researchers.

The regional trials conducted in 2012 involved public and private investigators who planted the germplasm at 14 locations. These locations were spread across the North Central states and Arkansas. The drought did influence the project; however, by using 14 testing locations good disease pressure was obtained for most of the maturity groups. The results of the regional trial have been summarized and released to all participants. The breeders will be able to use the results in the advancement and release of SDS-resistant varieties.

For the project overseen by Dechun Wang titled ?SDS Resistance QTL Identification and Confirmation from New Resistance Sources and Advanced Breeding Lines, out of seven candidate SDS resistance genes, two were reported in the literature and were co-localized with reported SDS resistance genes. These genes were identified in the new resistance source GD2422. Using advanced breeding lines entered in the 2011, the lines entered in 2012, the SDS Regional Tests, and over 5,300 SNP DNA markers, we identified five SDS resistance genes. Three of them were new SDS resistance genes. Two were among the five new SDS resistance genes identified from the new resistance source GD2422.

In efforts to identify factors that affect the development of SDS, cell-free toxic culture filtrates of F. virguliforme have been shown to cause foliar symptoms on soybean stem-cuttings similar to whole plant inoculations based on root infections. The objective of this study was to enhance SDS foliar severity of soybean stem-cuttings with stems immersed in cell-free toxic culture filtrates. Significant differences in foliar severity ratings occurred among 14 soybean genotypes using the optimized conditions to enhance SDS foliar severity of soybean stem-cuttings in cell-free toxic culture filtrates. The optimization of this stem-cutting assay has the potential to be used to compare cell-free toxic culture filtrates of different isolates and to evaluate soybean genotypes for differences in resistance. It also has broader implications when referring to the host-pathogen interaction and identifying factors that affect SDS development.