U.S. soybean farmers face a $1 billion problem each year in the form of yield losses from soybean cyst nematode (SCN).1 Yet rather than throw up your hands in defeat, get down in the soil and get your hands dirty. SCN can live hidden away in soil for years, but proactive management can expose it.2
By digging in and studying your crop’s roots, you can help mitigate soybean disease risks early and curb yield hits that appear much later—when it’s too late to take action.
When is the best time to scout for soybean cyst nematode symptoms?
Six weeks post-planting is the earliest you can begin scouting for soybean cyst nematode females on the roots of your soybean plants. You can continue scouting for SCN females throughout 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, so it’s easier to gently remove plants for closer inspection.
Another way to count SCN populations is to retrieve and send a soil sample for analysis at a lab where soybean cyst eggs can be counted using a microscope, but looking for visual markers is worth your time too.
Where and how to scout for soybean cyst nematode in your fields
When scouting for soybean cyst nematode females, gather a shovel and a magnifying glass before heading to the field. Start with a visual inspection to pinpoint where to dig.3 Focus on the most likely SCN hiding spots, including:
- Field entrances and exits: Machinery tires can introduce SCN-contaminated soil from other locations.
- Fencelines: 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 have located where to dig, take these steps:
1. Use a shovel to carve out a circle of soil around the soybean plant and dig it out. Try to stay 6” to 8” away from the plant base. Don’t tug or pull on the plant.5
2. Once the plant is out, shake the soil off. You can also dip the roots in a bucket of water and swirl them around.4 This removes dirt and exposes SCN females clinging to roots.
3. Get out your magnifying glass and examine the roots. Look 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. Color will vary, as SCN females start out white or cream and darken as they mature from yellow into brown.
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.
- Nodules are bigger than SCN females — about 10 times bigger, on average.
- 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 about 20 soil cores by digging to a depth of between 6” and 8” in a zig-zag pattern, averaging about one core per acre.6 If the field in question is larger than 20 acres, additional samples might be needed.
Another management strategy to incorporate into your operation is to plant soybean cyst nematode-resistant varieties. Because SCN resistance is increasingly overpowering legacy traits, work with your trusted adviser to explore existing and emerging trait options.
At planting, consider using Ilevo®, a soybean cyst nematode seed treatment that can help mitigate the risk of nematodes and protect yields. Soybean seed can be ordered from your seed supplier that is treated with Ilevo.
Experts are available to help you dial in 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.
