Did your soybean yield also suffer from SCN this year?
Suggested control measures
- Rotate the field with non-soybean crops.
- Keep weeds under control which also provide food over the winter.
- Plant varieties with the best SCN resistance genetics.
- Sample the soil in areas of low yield to find out your level of SCN population.
- If soil samples show non-detectable levels, and you have a 3-year rotation without double-cropping wheat and soybeans, then sample every 20 years.
- If you have non-detectable levels with a 3-year rotation, and you do double crop wheat and soybeans, then sample every 10 years.
- If you have non-detectable levels and you have a two year rotation of corn and soybeans, sample every 10 years.
- If your SCN populations are 40 to 2,000, and you rotate soybeans with corn and wheat, sample every 5 years.
- If SCN populations are 40 to 2,000, and you plant only soybeans, sample every year.
- If SCN populations are over 2,000, sample every year.
Fall is the best time to sample since it provides an opportunity for the lab to provide a report before you turn in your seed order for the following year.
How do you sample a field? Iowa State University SCN nematode specialist Greg Tylka provides a 9-minute YouTube video of sampling both soybean and corn fields for SCN populations.
Soybean cyst nematode (SCN) may have been consuming a good portion of your soybean yield if you noticed spots in your field where yields were much lower than others, but problems were not detectable during the growing season. SCN is now becoming resistant to soybean varieties that have been bred for resistance to SCN. Both rotation with other crops and soil sampling should be done regularly to monitor population levels.