Soybean Cyst Nematode: Test for the Pest

Soybean cyst nematode (SCN) is the leading pest of the U.S. soybean crop, causing more than $1.5 billion in annual losses. In severe cases, yield potential can be reduced by up to 80%. SCN is widely distributed across most areas where soybeans are grown in the United States. Purdue University estimates that about 45% of fields in Indiana might be infested with SCN, with 89 of 92 counties reporting SCN infestations. 

SCN is considered an invisible pest because symptoms are not typically visible in the field during the growing season unless the SCN population is very high. Troy Bauer with BASF said, “The problem with SCN is you can get up to a 30% yield reduction without seeing any visible above-ground symptoms.”

Additionally, symptoms of SCN injury can easily be confused with other problems such as nutrient deficiencies, herbicide injury, disease, and poor drainage. 

To help raise awareness of the importance of this invisible pest, BASF has partnered with the SCN Coalition through the month of October. Samples for SCN can be collected in any crop, any time of the year. However, after harvest is a convenient time to sample for SCN because it coincides with the highest egg counts and is a task that can be done while pulling soil fertility samples.

Sampling may be even more critical this year due to the widespread drought conditions this season across much of the Midwest. “SCN tend to thrive in hot, dry conditions and they reproduce more readily in those types of conditions. High pH soils and sandy soils are also conditions that favor SCN,” says Bauer. 

“What we encourage growers to do as they start thinking about the 2024 growing season is to go out and test soils for SCN to determine what levels they have. That way, they can develop a management plan as they start thinking about producing soybeans next year,” Bauer says. 

The patchy nature of the nematodes make it difficult to get accurate samples and results, so it’s important to collect soil cores from as large of an area as is practical. Bauer recommends that “if you have anywhere from 500 to 1,000 eggs per 100 cubic centimeter (cc) of soil, you probably need to start thinking about what management strategies you need in place.” 

Management strategies include rotation to a non-host crop such as corn, selecting resistant soybean varieties, and using seed treatments. 

Many soybean varieties offer PI 88788 resistance to SCN. However, not all SCN populations will react the same to this source of resistance. “PI 88788 is very effective, but the problem is we’ve been using it for about 30 years. Just as with any other source of resistance, if you keep hitting them with the same source over and over again, they start getting more tolerant and that’s what we’re finding with SCN. They are beginning to reproduce more readily on this source of resistance. If you can, rotate in PEKING source resistance, as well. BASF actually has a transgenic trait that will be on the market at the end of this decade, but it’s not available yet,” offers Bauer. 

Seed treatment products provide additional options for SCN management, including ILEVO seed treatment. “ILEVO is a proven product that has been on the market for a number of years and it kills nematodes right around the base of the root and also has effectiveness on SDS,” explains Bauer.

For more information on SCN, please visit the SCN Coalition website.