Plant pathogens and pests present continual challenges to the production and security of soybean. To manage plant pathogens an array of tools are used including cultural practices, cultivar resistance, and application of fungicides. Loss of any one of these tools will increase the reliance on the others, which in turn they will ore readily lose efficacy with the increased dependency on them. Continued, unbiased research on disease management tools are essential to provide information on cultural practices, cultivar resistance, and fungicide efficacy to better guide production decisions.

Project 1. To implement and monitor a statewide sentinel program to screen samples for early detection and population shifts of soybean pests and diseases including soybean rust, frogeye leaf spot, septoria brown spot, target spot, and cercospora blight, as well as screen for fungicide resistance. Expanding fungicide classes that will e used to include DMIs/Triazoles, MBC, and SDHI fungicides as well as screening both the frogeye leaf spot and target spot pathogens (but this depends on funding of project 3 of this proposal and other proposals for support). New and emerging invasive insects such as brown marmorated stink bug and kudzu bug will also be monitored.Utilize county agents and producers fields to establish approx. 10 soybean sentinel plots that will be monitored on a weekly to bi-weekly basis to track and report presence and severity of diseases and insect pests.

Project 2: To evaluate soybean cultivars and various fungicides in high to low disease pressure situations to determine yield potential, efficacy, and value to Tennessee producers, and fungicide resistance screening.
Commercial cultivars will be evaluated, with and without fungicide treatment, in low to moderate and high disease pressure locations. Similarly, different funcidides’ efficacies will be evaluated across 3 cultivars with varying susceptibility levels at the same locations. All data will be reported yearly and analyzed to assist producers in variety and fungicide selections, as well as uploaded to a searchable cultivar database. Samples collected from producers fields, research plots, and sentinel plots across the state will be used to screen the frogeye leaf spot and target spot pathogens for fungicide resistances to the Qol/Strobilurin, DMI/Triazole, MBC, and SHDI fungicide groups.

Project 3: Cover crops – investigate disease potential
Utilizing others’ field cover crop trials, fall and spring scouting/sampling will be conducted to evaluate different cover crop species disease potential for pathogens of soybean (namely soybean cyst nematode, charcoal rot, frogeye leaf spot, and target spot). Individual cover crop species will also be planted in the greenhouse and inoculated with the previous mentioned pathogens to determine their potential as a “green bridge” for diseases going into soybean.

Results from the proposed projects will build the research and Extension material on soybean disease management for Tennessee producers including, but not limited to:
- Disease ratings and yields on commercial varieties and fungicides
- Information on when and where soybean diseases and invasive insects are occurring in the state
- Risk/threshold models for foliar diseases and fungicide resistance to better guide fungicide decisions
- Information on soil pathogens distribution, infestation levels across the state, and management options

All projects will increase the exposure of the Soybean Promotion Board and the University of Tennessee to the soybean producers of Tennessee concerning their cooperative efforts to improve economic production through efficient and effective disease control. All projects will help increase yields and profitability for Tennessee soybean producers by assisting them in making accurate diagnosis of soybean pests and disease and the best decisions on when and what pesticides to use to manage diseases.