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The primary objectives of this research were to screen NDSU soybean breeding lines for resistance to major diseases and monitor soybean fields for new pathogens that can cause serious yield losses. In cooperation with Dr. Helms, the soybean breeder, we screened 60 advanced breeding lines for resistance to Phytophthora sojae race 4 or race 3. Over 80% of the NDSU lines were resistant to this pathogen. One breeding line resistant to race 4 was released in 2019 by NDSU and Dr. Helms as ND Rolette, a high yielding conventional soybean cultivar with a 00.09 maturity. Phytophthora root rot is a major disease in the Red River Valley and resistance is the primary way to prevent serious losses.

In August 2018, we surveyed 153 soybean fields in 10 counties (Barnes, Cass, Dicky, Griggs, LaMoure, Richland, Ransom, Sargent, Steele, and Traill) for evidence of sudden death syndrome (SDS), caused by Fusarium virguliforme. This disease had not previously been reported in North Dakota, but it is a serious disease in other soybean producing states including Minnesota and South Dakota. We were searching for specific foliar symptoms associated with SDS. In several fields in Richland Co., we discovered classic foliar symptoms of SDS. Plants were collected and fungi were isolated from the roots. These fungi caused disease in greenhouse experiments and were identified by DNA analysis as F. virguliforme. SDS is therefore, a new soil-borne disease of soybean in North Dakota.

In addition to finding SDS, we also found for the first time a soybean field with major damage from charcoal rot in 2018. This is a soil borne disease caused by the fungus Macrophomina phaseolina. The field was in an area in Cass Co. where there were drought conditions during July and August. This 210 acre field had approximately 60% of the plants dead or dying by the beginning of September. The information we gain from studying the SDS and Charcoal rot diseases will be used to prepare information for growers, crop scouts, and others in the soybean industry in ND, so these diseases can be identified, disease development can be understood, and management options can be explained. Both diseases have the potential to cause extensive yield loss in soybean. A major effort in our future research will be to find resistance to these diseases and incorporate resistance into breeding material for North Dakota.