Research HighlightsEvaluating the Effect of Nematode-Protectant Seed Treatments for Soybean Cyst Nematode Management
In this article, you’ll find details on:
- Field trials in multiple locations and over multiple years compared the effect of six nematode-protectant seed treatments on soybean cyst nematode and soybean yield.
- Across all trials, SCN reproduction increased each season, but some treatments lowered soybean death syndrome severity.
- The research indicated that nematode-protectant seed treatments can provide a benefit to soybeans, but that results can be inconsistent from field to field.
By Carl Bradley, Extension Professor, Plant Pathology Extension Specialist, University of Kentucky
Reprinted from Kentucky Soybean Sentinel, spring 2025
The soybean cyst nematode is one of the most important soybean pathogens in the United States. In Kentucky alone, SCN was responsible for an estimated average yield loss of over 2.7 million bushels, worth approximately $33.4 million per year from 2019 to 2023.
Practices recommended for management of SCN include rotating soybean with non-host crops, planting resistant varieties and considering using a nematode-protectant seed treatment. Of these management practices, nematode-protectant seed treatments are the most recent to come available to farmers, with several products now on the market.
A multi-state research project to evaluate the effect of nematode-protectant seed treatments on SCN and soybean yield was conducted in field trials from 2019 to 2021. Research trials were located in Arkansas, Delaware, Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Missouri, Nebraska, South Dakota, and Wisconsin, supported by the soybean checkoff through the North Central Soybean Research Program, the Kentucky Soybean Promotion Board, the Michigan Soybean Committee and the Missouri Soybean Merchandizing Council. In addition, trials were conducted in Ontario, Canada.
In total, data were collected from 51 site-years, or environments. A total of eight treatments were tested, including a nontreated check and a fungicide and insecticide base treatment of metalaxyl, pyraclostrobin, fluxapyroxad and clothianidin. All other treatments included the fungicide and insecticide base plus one of the following options:
- BIOST, heat-killed Burkholderia rinojensis from Albaugh.
- Aveo EZ, Bacillus amyloliquefaciens from Valent.
- Clariva, Pasteuria nishizawae from Syngenta.
- ILEVO, fluopyram from BASF.
- Trunemco, Cis-jasmone, Bacillus amyloliquefacien from Nufarm.
- Saltro, pydiflumetofen from Syngenta.
The table shows the results of the research trials, averaged across all 51 site-years. The SCN reproduction factor measures reproduction of SCN during the growing season, where a reproduction factor less than 1 indicates that SCN populations decreased from the beginning to the end of the season, a reproduction factor equal to 1 indicates that SCN populations stayed the same from beginning to end of the season, and a reproduction factor greater than 1 indicates that SCN populations increased from the beginning to the end of the season.
The sudden death syndrome severity index is a measurement of the amount of SDS, where the greater the number, the greater the amount of SDS.
Plots were harvested with small plot research combines that were outfitted with special equipment that measure weight and grain moisture used to determine soybean yields.
Key takeaways are:
- SCN reproduction increased from the beginning to end of the season for all treatments, and no statistically significant differences in SCN reproduction were observed among the treatments.
- Compared to the nontreated check, the Saltro and ILEVO treatments were the only ones that had statistically significant lower SDS severity index values
- The Saltro and ILEVO treatments were the only ones that had statistically significant greater yields than both the nontreated check and the fungicide and insecticide base treatment
Overall, the results of this research indicated that nematode-protectant seed treatments can provide a benefit to soybeans, but that results can be inconsistent from field to field. This means that it is still important to use traditional SCN management practices such as rotating to non-host crops and planting SCN-resistant soybean varieties. As always, the first step in managing SCN is to test for SCN in your own fields. For example, the Kentucky Soybean Promotion Board is continuing to support Kentucky soybean farmers by paying for SCN testing in their fields.
Additional Resources:
Management of soybean cyst nematode and sudden death syndrome with nematode-protectant seed treatments across multiple environments in soybean Plant Disease 108:1729-1739
Meet the researcher: Carl Bradley
Published: Apr 7, 2025
The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.
