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Research Highlights
SCN Coalition Enters New Phase of Farmer Support

Soybean cyst nematode. Photo: Sam Markell, The SCN Coalition

By Barb Baylor Anderson

Soybean cyst nematode (SCN) causes about $1 billion in soybean yield losses annually. In fact, SCN causes more yield loss to soybeans than any other disease or insect pest. 

What’s more, yield losses could increase as aggressive SCN populations continue to slowly overcome the genetic resistance in varieties farmers have used for years to manage it: PI 88788.

The North Central Soybean Research Program (NCSRP), with funding from several state soybean checkoff boards and the United Soybean Board, has been successfully helping farmers recognize and mitigate yield losses to SCN. Now, the SCN Coalition is entering a new phase of discovery and education.

“We can help prevent future yield loss by increasing awareness of the new threat presented by SCN,” says Sam Markell, North Dakota State University Extension plant pathologist and principal investigator for the SCN Coalition project. “As SCN continues to adapt to genetic resistance and the ways we manage it change, it is critical for the SCN Coalition to provide the most current information so farmers can determine best ways to manage SCN on their farms.”

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Mike Schlosser, who serves on the NCSRP Board of Directors, is appreciative of the SCN Coalition’s efforts. “NCSRP has a goal of identifying the broad scope of the populations and severity that exist since SCN is most prominent in the Midwest,” says Schlosser, who also is a director for the North Dakota Soybean Council from Edgeley, N.D. “NCSRP represents a combined effort to pool checkoff funds from all of these states and find solutions.” 

When the SCN Coalition was created several years ago, the objectives were to increase farmer and industry awareness of the growing threat to soybean yields as nematode populations adapted to PI 88788 and to unify the public and private sectors around straightforward management recommendations and their communication to slow the erosion of PI 88788 effectiveness. 

To date, the group has largely provided growers with focused educational materials on the tools available, such as soil sampling, resistance and rotation, and how to use them to manage SCN. And while Markell says messages have changed little since the 1990s, understanding of the science behind them is now dramatically different. The SCN Coalition sees as next steps helping farmers understand research developments by translating all SCN-related scientific discoveries into understandable language that helps them tailor advanced management decisions. 

“Our overall message remains, ‘Take the Test: Beat the Pest.’ Soil testing is the most reliable and effective way to determine if you have SCN and to evaluate if your management tools are working,” says Markell. “Active management will slow adaption of SCN to genetic resistance.”

One exciting SCN research effort underway funded by NCSRP may forever change how soybean resistance to SCN is used. With traditional breeding methods, soybean geneticists and breeders at the University of Illinois and University of Missouri have created soybean plants with a unique combination of SCN resistance genes. The resistance genes came from different chromosomes of the breeding lines PI 88788, PI 437654 and PI PI567516C and from wild soybeans.

Field experiments are being conducted to determine how growing plants with the new resistance gene combinations repeatedly for several years, and also growing them in specifically designed rotation sequences, affect SCN numbers and resistance durability. Markell says the prescriptive approach to deploying resistance genes to manage SCN has never been attempted but will likely pave the way towards more effective and strategic deployment of SCN resistance genes in the future to maximize both effectiveness and durability of SCN resistance.

The SCN Coalition will now also include other economically important nematodes of soybeans into their efforts, including root-knot and reniform nematode. The expansion supports the National Soybean Nematode Strategic Plan and the needs of many farmers who must manage multiple economically important nematodes and associated diseases in their soybeans.

“Checkoff funded research is supporting efforts to battle SCN and other nematodes on all fronts; from unravelling how nematodes cause disease so we can produce better resistant varieties, to the effect of novel nematicide seed treatments,” says Markell. “With all of this research and multiple states involved, the soybean checkoff is leading the way in the fight against SCN.”

Watch this video: Melissa Mitchum discussing the Tode Farm. The “Tode” farm is a rich genetic resource for researchers.

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.