By Blake Jackson
According to Mandy D. Bish and Jefferson Barizon of the University of Missouri Plant Science & Technology, a statewide survey conducted during 2024 and 2025 examined 200 soybean fields across 81 Missouri counties to identify plant-parasitic nematodes affecting soybean production.
Supported by the Missouri Soybean Merchandising Council, the survey provided a comprehensive look at nematode populations across all nine crop reporting districts in the state.
Researchers detected 10 different nematode groups in soybean fields. The most widespread were spiral nematodes, root-lesion nematodes, and soybean cyst nematodes (SCN), found in 85%, 84%, and 80% of sampled fields, respectively.
Other species, including stunt, lance, root-knot, dagger, pin, ring, and stubby-root nematodes, occurred less frequently or were limited to specific regions.
Many fields contained multiple nematode species. Nearly half of the surveyed fields had three different plant-parasitic nematode groups present. However, researchers noted that nematode presence alone does not necessarily result in economic losses, as the impact depends on population density, crop susceptibility, and field conditions.
Among all species, soybean cyst nematode remains the greatest concern. Positive fields had a median population of about 2,100 eggs per 100 cubic centimeters of soil, although some fields recorded nearly 34,000 eggs. Researchers also evaluated how well SCN populations reproduced on commonly used resistance sources.
Results showed that the widely used PI 88788 resistance source no longer provides strong protection against many Missouri SCN populations. On average, for every 100 females developing on a susceptible soybean variety, about 66 females developed on PI 88788-resistant soybeans.
In contrast, the Peking resistance source performed significantly better, with median reproduction rates of about 10 females per 100.
Using typical Missouri production conditions, researchers estimated that SCN populations at the statewide median level could reduce yields by approximately 8.9%, equal to about 4.5 bushels per acre or nearly $58 per acre in lost revenue.
To reduce losses, growers are encouraged to regularly test soils, rotate resistance sources such as PI 88788 and Peking, include non-host crops like corn in rotations, and consider nematode-protectant seed treatments as part of an integrated pest-management strategy.
Photo Credit: istock-ds70
Categories: Missouri, Crops, Soybeans, Education