Soybean cyst nematodes (SCN) are a plant-parasitic roundworm that attack soybeans and found in Saline, Jefferson, and Gage counties. The pest is not new or unfamiliar to area farmers and agronomists. However, sometimes we get to comfortable with old issues. As a reminder, SCN is the #1 yield-grabbing pest in U.S. soybean production.
Soybean cyst nematodes or SCN were found in 1954 affecting soybeans in North Carolina, but not found until 1986 in Richardson County, Nebraska. Nebraska was the last major soybean producing state to find SCN. A Nebraska SCN distribution study published in 1989 confirmed the presence of SCN in southeast Gage County in 1988 (report below). Today, SCN has been identified in 59 counties, including all counties in eastern Nebraska.
My colleagues, Melissa Bartels, Kyle Broderick, and Tamra-Jackson Ziems, wrote two great articles (Managing SCN Starts Now and SCN Survey Update and 10th Annual Tode Awards) about SCN on our statewide website, CropWatch, on March 17. I want to highlight a few things they discussed in terms of resources available and management tactics to help control SCN.
Let us use the same acronym, SCN to remember the management steps:
- (S) soil sampling and free SCN analysis,
- (C) crop rotation, and
- (N) new soybean varieties and rotation of varieties.
The first step is the take soil samples (S) in your fields similar to the process for soil nutrients. In my last column, I mentioned some of the resource guides and tools available at our Extension offices including borrowing a soil probe to sample for soybean cyst nematodes (SCN). We do have sample bags for free SCN analysis (Figure 1) in the Beatrice, Fairbury, and Wilber Extension offices. The cost of the analysis is funded by the Nebraska Soybean Board and analysis performed at the UNL Plant and Pest Diagnostic Lab in Lincoln.
The second step, if SCN are found in your field, is crop (C) rotation or planting more non-host crops such as corn, wheat, and alfalfa. Most rainfed fields are already are in a corn-soybean rotation, so changing to a corn-corn-soybean, corn-soybean-wheat, or alfalfa will provide additional benefits. As a part of crop rotation, controlling winter annual weeds species that can serve as alternative hosts for SCN is important.
The third step is to select new (N) soybean varieties with SCN-resistance and rotate the sources of resistance. Most soybean varieties have the PI – 88788 single source of resistance, but some SCN can now reproduce or overcome this genetic resistance. The other main source of resistance is called Peking. Additionally, several seed treatments are available to provide additional protection. The Peking varieties originally lagged behind in yield compared to PI – 88788, but companies now have very competitive varieties.
For more information about soybean cyst nematodes (SCN) and general inquiries about other agronomic resources from Nebraska Extension, feel free to contact me at or 402-821-1722. Know your crop, know your tech, know your bottom line at croptechcafe.org.
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