This project addresses “soybean disease, nematode, insect pest and abiotic stress biology, management and yield loss mitigation,” a stated key area of research and outreach focus for ISA. The effects of SCN-resistant soybean varieties and nematode-protectant seed treatments on SCN numbers and yield loss will be determined in 36 different field experiments (4 different studies conducted in each of Iowa’s 9 crop-reporting districts). Also, a multi-faceted communication effort will disseminate project results annually in print, electronic media, and ag radio and through 10 to 20 in-person and virtual presentations to Iowa soybean farmers.

1) the agronomic performance and SCN control provided by resistant soybean varieties grown by Iowa farmers, with special emphasis on new varieties with Peking SCN resistance
2) the effects of increasing SCN reproduction on yields of SCN-resistant soybean varieties
3) the effects of nematode-protectant seed treatments on agronomic performance and reproduction of SCN on resistant soybean varieties

Compile a list of SCN-resistant soybean varieties for Iowa farmers
Evaluate SCN-resistant soybean varieties for yield and SCN control in field experiments
Evaluate nematode-protectant seed treatments for effects on yield and SCN numbers

Updated September 8, 2025:
In the last 6 months (1 October 2024 through 31 March 2025) we:

- compiled and prepared a publication titled “Soybean cyst nematode-resistant soybean varieties for Iowa,” posted it online in October 2024 - see https://doi.org/10.37578/ONKA5947 and in a PDF file attached to this report
- harvested plots in all 9 SCN-resistant variety trial experiments and 27 seed treatment evaluation experiments to determine yields in October 2024
- collected soil samples from every plot the variety trial and seed treatment experiments at the time of harvest to determine final SCN soil population densities in October 2024
- extracted SCN cysts, then extracted and counted eggs from 3,240 soil samples collected from the SCN-resistant variety trial and seed treatment experiments at harvest, then counted the eggs to determine final SCN egg population densities from November 2024 through March 2025
- compiled and analyzed yield and SCN population density data from the SCN-resistant variety trial and seed treatment experiments in December 2024
- prepared a printed report of the SCN-resistant soybean variety evaluation experiment results, printed the report, and then had the report distributed to 48,000 Iowans as the cover story (see here) and as a special insert in the January 11, 2025, issue of the Iowa Farmer Today newspaper - the report also is available online - see https://doi.org/10.37578/UDSP9793 and in a PDF file attached to this report
- published three articles in the ISU Integrated Crop Management Newsletter about the resistant variety list and sampling for SCN - listed below:

· Tylka, G.L. 2024. SCN-resistant soybeans varieties for 2025 including 200 with Peking resistance. Iowa State University Integrated Crop Management News (24 October 2024). https://crops.extension.iastate.edu/cropnews/2024/10/scn-resistant-soybeans-varieties-2025-including-200-peking-resistance

· Tylka, G.L. 2024. Quick guide to soybean varieties with Peking SCN resistance for Iowa. Iowa State University Integrated Crop Management News (24 October 2024). https://crops.extension.iastate.edu/post/quick-guide-soybean-varieties-peking-scn-resistance-iowa

· Tylka, G. 2024. Fall is a great time to collect soil samples for SCN. Iowa State University Integrated Crop Management News (7 November 2024). https://crops.extension.iastate.edu/post/fall-great-time-collect-soil-samples-scn

- began contacting seed companies to request seeds of SCN-resistant soybean varieties for 2025 field experiments in January-February 2025
- contacted FMC, Syngenta, and UPL personnel for seeds treated with Avodigen, Victrato, and NIMAXXA, respectively, for 2025 small-plot field experiments
- began receiving seed from seed and seed-treatment companies for 2025 field experiments, designed the 2025 field experiment layouts, and began packaging of seeds for the various experiments in March 2025
- received 121 Peking varieties from seed companies to consider including in variety evaluation experiments in 2025; this number is up from 88 in 2024
- conducted final soil sampling of farmer fields throughout Iowa to allow for selection of the final 2025 experimental field locations in March 2025

View uploaded report

View uploaded report 2

The overall goal of this project is to provide Iowa soybean farmers with research-based information about resistant varieties and seed treatments for managing SCN.