How to Scout Soybean Roots for Soybean Cyst Nematode Symptoms

U.S. soybean farmers face a $1.5 billion problem each year in the form of yield losses from soybean cyst nematode (SCN).¹ And while SCN can hide in soil for years, the good news is that proactive management can improve soybean cyst nematode control.

Studying your crop’s roots will provide valuable information that can help you mitigate SCN damage and curb yield loss.

When is the best time to scout for soybean cyst nematode symptoms?

About six weeks after planting, begin scouting for soybean cyst nematode females on roots.² Continue scouting during the growing season until about three to four weeks before harvest.

Starting early in the season is a good idea because soybean roots haven’t fully grown into the soil profile. You can also retrieve and send soil samples for analysis at a lab where soybean cyst eggs can be counted using a microscope.

(Gregory Tylka, Iowa State University, Bugwood.org)

Where and how to scout for soybean cyst nematode in your fields

Use a shovel and a magnifying glass to scout for soybean cyst nematode females. Focus on the most likely SCN hiding spots, including:

• Field entrances and exits: Machinery tires can introduce SCN-contaminated soil from other locations.
• Fence lines: Wind blows soil into mounds, which can harbor SCN.
• Structures: Soil adjoining barns, equipment and outbuildings can host SCN.
  

Areas where yields are unexplainably lower than expected are a prime place to dig, too.

Steps for soybean cyst nematode sampling

Once you decide where to dig, take these steps:

1. Use a shovel to carve out a circle of soil around the soybean plant. Dig down about 8”, then gently ease the plant out.³

2. Shake the soil off the roots or dip them in a bucket of water and swirl them around.

3. Get out your magnifying glass and examine the roots for SCN adult females. They are about the size of a period in a printed sentence (roughly 1/32”) and resemble the shape of a lemon.⁴ Color will vary, as SCN females start out white or cream and darken as they mature.

(Elizabeth Bush, Virginia Polytechnic Institute and State University, Bugwood.org)

How can I tell the difference between soybean cyst nematode females and nitrogen nodules?

It’s common to mistake Rhizobium root nodules for SCN adult females. There are two key differences that can make it easier to tell them apart.

1. Nodules are bigger than SCN females — about 10 times bigger, on average.⁵
   
2. Nodules are pink or blood-red on the inside, whereas SCN females are not.

Soil testing and other soybean cyst nematode management practices

Beyond visual inspection, you can get quantitative data on SCN populations with soil sampling. This can be done at any point in the growing season, but is typically done post-harvest.

Take between 20 and 25 soil cores by digging to a depth of between 6” and 8” in a zig-zag pattern.⁶

Other management strategies to incorporate into your operation include crop rotation and planting soybean cyst nematode-resistant varieties. Because SCN resistance is increasingly overpowering legacy traits, work with your trusted adviser to explore emerging trait options such as BASF’s Nemasphere™ nematode resistance trait, anticipated in 2028 pending regulatory approval.

At planting, consider using Ilevo®, a soybean cyst nematode seed treatment that can help mitigate the risk of nematodes and protect yields. Soybean seed treated with Ilevo can be ordered from your seed supplier.

Experts are available to help you develop your SCN action plan for this season and beyond. Contact a trusted adviser such as your regional BASF representative to get the answers you need for soybean cyst nematode control.

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Endnotes

1. Tylka, Greg. “New Data-Based Calculator Estimates Economic Yield Loss from SCN in Individual Fields.” Integrated Crop Management, Iowa State University Extension and Outreach, 10 Nov. 2023,https://crops.extension.iastate.edu/cropnews/2023/11/new-data-based-calculator-estimates-economic-yield-loss-scn-individual-fields. Accessed 15 June 2026.
2. Betts, Alyssa K. “Scouting Soybeans for Soybean Cyst Nematode.” Weekly Crop Update, UD Cooperative Extension, 11 June 2026,https://sites.udel.edu/weeklycropupdate/?p=28213. Accessed 15 June 2026.
3. Tylka, Greg. “Dig into Scouting for SCN.” Integrated Crop Management, Iowa State University Extension and Outreach, 12 June 2023,https://crops.extension.iastate.edu/cropnews/2023/06/dig-scouting-scn. Accessed 15 June 2026.
4. Murillo-Williams, Adriana, Paul D. Esker, and Alyssa Collins. “Don’t Guesstimate: Free Testing for Soybean Cyst Nematode (SCN) is Available.” Penn State Extension, 21 Apr. 2026,https://extension.psu.edu/dont-guesstimate-free-testing-for-soybean-cyst-nematode-scn-is-available. Accessed 15 June 2026.
5. Bissonnette, K., T. Faske, and A. Tenuta. An Overview of Soybean Cyst Nematode. Crop Protection Network, 2021, CPN-1022, doi:10.31274/cpn-20210423-0.https://cropprotectionnetwork.org/publications/an-overview-of-soybean-cyst-nematode. Accessed 15 June 2026.
6. Wilson, John, and Loren Giesler. “A New Reason to Sample for SCN This Fall.” CropWatch, University of Nebraska–Lincoln, https://cropwatch.unl.edu/new-reason-sample-scn-fall/. Accessed 15 June 2026.