New Guide Helps with Soy Pest
Published: Friday, September 4, 2026
As soybean harvest approaches, farmers have a narrow, high-value window to uncover a hidden yield thief. Soybean cyst nematode (SCN) and other parasitic nematodes can cut yields sharply with no visible symptoms, and fall, right after harvest, is the best time to test soil and find out what's lurking. To help farmers act on that window, the Soy Checkoff is directing growers to the Soybean Nematode Management Guides, a set of science-based tools it helped fund to identify and manage four yield-robbing nematode species.
"Protecting soybean yield starts with knowing what's in your fields, and these guides put that knowledge directly in farmers' hands," said Laurie Isley, United Soybean Board director and Michigan farmer. "As a farmer, I know how much an invisible pest like SCN can cost you before you ever see a symptom above ground. This is exactly the kind of practical, science-based tool your checkoff investment is meant to deliver."
Nematode management isn't one-size-fits-all, as several species can infest soybean fields, each with distinct life cycles, symptoms and impacts on yield. Funded by the checkoff and developed by Extension plant pathologists and nematologists, the Soybean Nematode Management Gu-ides provide soybean farmers with science-based tools to soil test and identify nematode infestations, develop tailored management strategies, and recover lost yield potential caused by:
• Soybean cyst nematode (SCN): Known as the No. 1 yield-grabbing pathogen of the soybean crop in North America, SCN causes up to 30% yield loss without demonstrating noticeable aboveground symptoms, leading to annual losses exceeding $1.5 billion.
• Root-knot nematode (RKN): Another widespread threat, RKN species, including Southern RKN, can cause 25% yield loss in individual fields and is found in most soybean production regions in the U.S.
• Root lesion nematode (RLN): A collection of more than 100 species, RLN's impact on yield extends beyond soybeans. With a broad host range, RLN can also reduce yield in rotational crops, including corn, and lead to recurring economic losses.
• Reniform nematode: A significant pathogen in the southern U.S. for cotton and soybean farmers, reniform nematode can cause more than a 10% yield loss in individual fields.
Research conducted by The SCN Coalition of 271 farmers in southern soybean areas shows roughly 80% of farmers are aware of SCN and RKN, while other nematode species that impact soybean yield, like RLN and reniform, are less understood. When high numbers of these nematodes coincide with drought or other stressful environmental conditions, soybean yield reductions can become even more severe. Other research findings include:
• 44% said they scout or conduct nematode soil sampling
• 57% rely on aboveground symptoms to diagnose nematodes
• 72% rely on crop rotation to manage nematodes
• 65% support checkoff-funded research to develop new nematode management tools
"Thanks to efforts from The SCN Coalition, soybean farmers have been exposed to active SCN management messages, but nematode pressure doesn't stop there," said Dylan Mangel, plant pathologist at the University of Nebraska-Lincoln. "Addressing these lesser-known and still damaging nematode species helps farmers close information gaps and take a more comprehensive approach to protect yield from nematodes. It's also an opportunity for the Coalition to expand its reach and impact."
While it's impossible to eliminate nematode pressure from an infested field, the Soybean Nematode Management Guides arm soybean farmers with multiple active management strategies shown to effectively reduce plant-parasitic nematodes' impact on yield.
"An integrated approach using multiple active management strategies can keep nematode populations low and protect soybean yield," said Horacio Lopez-Nicora, soybean pathologist and nematologist at the Ohio State University. "By adopting a proactive, informed management plan and using the practices found in these management guides, farmers can reduce plant-parasitic nematode pressure and help protect soybean yield and overall crop productivity."
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