Update:
In our previous regional evaluations, fluoyram (ILeVO, Bayer CropScience) seed treatment or in-furrow application was found superior to manage SDS than other fungicide products evaluated. A manuscript was published in Plant Disease (Plant Disease 100:1339-1350). We continue evaluating new products including biological fungicides to compare them with base seed treatment and ILeVO in their ability to reduce SDS. In 2017, we performed field experiments in Iowa, Indiana, Michigan, South Dakota, Wisconsin and Ontario, Canada. We evaluated 9 fungicide products applied as seed and foliar applications on SDS susceptible and resistant cultivars. Plant population, root rot, root dry weight, foliar SDS incidence and severity, and yield data were recorded using standard protocols and data are being collected and analyzed.

• We completed field experiments in Iowa, Indiana, Michigan, Wisconsin and Ontario for a study coordinated by Dr. Shawn Conley to investigate the economic risk and profitability of seed treatments on soybeans planted at different populations. The three seed treatments consisted of untreated control (UTC), a commercial base treatment (CB), and CB treatment + IleVO were compared at different plant populations. Soybean yield was evaluated in fields with and without a history of SDS. A manuscript has been published in Crop Science (Crop Sci. 56:2251-2262) and an extension publication was posted in the CoolBean website. Economic risk and profitability of seed treatments and seeding rate for each seed treatment was also estimated using different soybean prices. The CB and ILeVO seed treatments increased profit at each grain sale price and across all seeding rates compared to the UTC.

• A manuscript evaluating planting date and seed treatment effect on SDS development has been published in Plant disease (Plant Disease 100:1735-1743).

• In 2017, we continued field experiments in Iowa, Indiana, Michigan, Wisconsin and Ontario to investigate the effect of corn residue on SDS development. We compared two levels of residue removals and two tillage systems in corn and soybean rotation system. We collected plant population, root rot, foliar SDS, and yield data and they are being analyzed.

• We completed field experiments on determining how increasing SCN resistance to SCN-resistant cultivars will affect SDS resistance performance. A manuscript has been posted online in Plant Disease. In summary, we found PI88788 resistance source has been broken by nematode population in all tested sites except in Rodney, Ontario. SCN resistance played a critical role on SDS development. Cultivars with no resistance to SCN had the highest disease and lowest yield. Even though, the PI 88788 type resistance was not holding up, any type of SCN resistance led to greater yields, lower SDS, and lower SCN reproduction than the cultivars with resistance. Fall season SCN population density and SDS were positively correlated.

• We identified fields with long-term fertility experiments in collaboration with Dr. Antonio Malarino, Professor of Nutrient Management Research and Extension, ISU, at the Northeast Research Farm in Nashua and the Southeast Research Farm in Crawfordsville, to determine how soil potassium levels affect SDS. We collected SDS incidence and severity and yield data in 2017. Data are being analyzed. We are working on establishing protocols for greenhouse studies.

• In 2017, we tagged plants with different visual ratings of SDS from low to high. Root samples were collected to quantiy F. virguliforme. DNA extraction is in process. Next step will be to quantify the pathogen in root tissue and determine the correlation with visual ratings.

• To determine the soil sampling protocol for determining SDS pathogen level in soil, we identified fields with low and high risk of SDS based on previous years SDS severity and collected samples in different time and from different soil zones. DNA extraction has been completed and DNA samples are being processed for qPCR.

• We presented our research reports at professional meetings, on Plant Management Network, many state or province level talks, seminars, media interviews, talk in field days and conferences for farmers and also published in state newsletter articles, several media releases etc. To communicate with researchers, we published 6 manuscripts in peer-reviewed journals. We also had several press releases, including some jointly with NCSRP, based on results from this project. We developed two regional publications through the Crop Protection Network (Scouting for Sudden Death Syndrome on Soybean and Soybean Disease Management: Sudden Death Syndrome). These are linked to the SRII site. We also updated SRII with information from this proposal.

• The result from this study will have directly benefited soybean farmers in the North Central region and also establish foundation to address future research and management questions.