If your 'hair isn't on fire' regarding SCN, it should be!: How to get free sample analysis & management recommendations

This article was written by Angie Peltier, UMN Extension educator-crops.

Figure. Soybean roots, with yellow arrows
pointing to swollen female SCN and the white
 arrow to a  much larger nitrogen fixing nodule. 
Photo: Angie Peltier

Soybean cyst nematode (SCN) is a microscopic worm that is attracted to and infests soybean roots where it uses for its own growth and development the water and sugars that the soybean plant takes up to develop leaves, flowers, pods and beans (Figure). Capable of causing significant yield loss without alerting a producer of its presence, SCN caused an estimated $7.32 million in lost yield in 2023 in Minnesota (Crop Protection Network, 2024), making it the top yield-limiting pathogen of soybean in Minnesota and throughout the Midwest.

One of the most sickening feelings is to visit a field to assist a farmer or crop consultant with diagnosing a soybean production issue only to have to break the news to the unsuspecting that the field is infested with SCN. The reasons my 'hair is on fire' regarding SCN are many: 1) SCN can cause up to 30% yield loss without also causing diagnostic above-ground symptoms, 2) poor yields caused by SCN can easily be blamed on causes other than SCN, 3) SCN egg counts tend to rise more quickly and more slowly drop with management in the alkaline soils of western MN, 4) the best time to begin monitoring for and actively managing SCN was last year, or even the year before!

Know your numbers!

SCN management recommendations are based on SCN egg counts taken from a composite soil sample. To estimate a field’s SCN population density, a composite sample is collected by taking small subsamples (soil cores) of soil 8 inches deep using a soil probe from 15-20 different spots from a field area no larger than 10-20 acres. 

How to receive sampling supplies  

In an effort to help Minnesota soybean producers to “know your numbers” the Minnesota Soybean Research & Promotion Council is sponsoring a fall 2024 SCN Sampling Program This is your last chance to participate in this check-off sponsored program as we do not have funding to carrying this program into the 2025 growing season. Interested  Minnesota farmers and crop advisors can fill out a form to receive bag labels and sampling instructions via mail. Note that for those that participated in this program in 2023, we have changed the lab analyzing the samples due to both pricing and staffing issues. Test results will likely be returned more quickly than in 2023.