Updated November 21, 2019:
The goal of this six-state program was to develop cost-effective and sustainable management options for major foliar diseases of soybean. This was to be accomplished by gaining a better understanding of the biology of foliar diseases, identifying disease-resistant varieties, and assisting in the development of resistant germplasm. In several crop production systems, fungal pathogens have developed resistance to fungicides. Determining the best fungicide resistance management options is critical to maintain the longevity of effective fungicides. This highlights the importance of monitoring the development of resistance in pathogens to fungicides, and to identify alternative classes of fungicides to manage these diseases effectively.

The ultimate goal of this work was to provide immediate-term benefits and long-term solutions to minimize the risks of soybean foliar pathogens and to help ameliorate the 10–15% of yield losses caused by any one of the major foliar diseases. Results from this project will help attain this goal. Some specific results include the discovery that, in the U.S., Cercospora leaf blight seems to be caused by a pathogen different from the one that has been reported to cause the disease. This will impact the development of strategies to manage this disease. With frogeye leaf spot, tools were developed to better assess the ability of different strains of the pathogen to overcome resistance in soybean. Also, breeding efforts led to the identification of potentially novel sources of resistance to this pathogen in soybean. Different tools were used to study and to monitor the development of resistance to fungicides in several pathogens (the frogeye leaf spot pathogen, the Cercospora leaf blight pathogen, and the Septoria brown spot pathogen). This will allow the development and update of soybean pathogen maps to monitor the development of resistance to fungicides and to modify recommended management practices accordingly. In addition, in this project, different strategies were used to study Soybean Vein Necrosis Virus (SVNV). The virus was found to affect soybean yield and resistance to the virus was identified in soybean germplasm. Efforts are ongoing to further characterize the impact of this virus and its vector, soybean thrips, on soybean yield.