Pest Control · May 2025 · 5 min read
Soybean cyst nematode is the number-one yield robber in U.S. soybeans, often causing losses before any above-ground symptoms appear. A proactive detection and resistance strategy is essential for every soybean grower.
Collect soil samples in the fall after harvest, pulling 15–20 cores per field at a 6- to 8-inch depth and combining them into one composite sample. Send samples to a lab that reports egg counts per 100 cc of soil. Fields above 2,000 eggs per 100 cc warrant immediate attention, while even low counts signal that populations are building and management changes are needed.
Most SCN-resistant varieties carry the PI 88788 source of resistance, but overuse has allowed nematode populations to adapt. Rotate to varieties with Peking or PI 89772 resistance sources where available. Check your seed company's SCN rating and pair resistant genetics with seed treatments containing nematicide active ingredients for added early-season protection.
Rotate soybeans with non-host crops like corn, wheat, or grain sorghum for at least one year to reduce egg counts. Continuous soybeans allow SCN populations to multiply rapidly, even with resistant varieties. Combining crop rotation, resistance source rotation, and cover crops that suppress nematodes—such as certain brassicas—provides the most durable long-term control.
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