During 2024 and 2025 and with support from the Missouri Soybean Merchandising Council, we surveyed 29 soybean fields across 11 North Central Missouri counties (Adair, Carroll, Chariton, Grundy, Linn, Livingston, Macon, Mercer, Putnam, Randolph, and Sullivan) to better understand which plant-parasitic nematodes are present and at what population levels.
Nematodes are common, but presence does not always mean damage
Seven types (or taxa) of plant-parasitic nematodes were detected in the region. Spiral nematode was found in 90% of fields, soybean cyst nematode (SCN) in 83%, and root-lesion nematode in 79%. Lance, stunt, dagger, and ring nematodes were detected less frequently (Figure 1). Finding a nematode does not necessarily mean it is causing yield loss. Risk depends on the nematode, population density, crop, and field conditions.
Figure 1 Prevalence (% of fields with detection) and population densities of plant-parasitic nematodes detected in 29 soybean fields across 11 counties in North Central Missouri. Median and maximum population densities are based on positive soil samples only and are reported per 100 cm³ of soil. In the host column, icons indicate the nematode's potential to feed on soybean and/or corn. Host status may vary among nematode species within each group.
SCN was widespread in North Central Missouri, but population densities varied considerably among fields. Among fields where SCN was detected, the median population was 800 eggs/100 cm³ soil, while the maximum reached 20,200. This variation reinforces why individual fields need to be sampled rather than assuming neighboring fields have similar SCN pressure.
SCN reproduction differs among resistance sources
We also tested how well these SCN populations reproduce on common sources of SCN resistance. Among the North Central Missouri SCN populations tested, for every 100 females that developed on a susceptible soybean, a median of 66 females developed on PI 88788 (the most common SCN resistance source found in Missouri soybean). On Peking, the median was much lower with 5 females per 100 on susceptible soybean. The higher reproduction on PI 88788 reinforces the importance of knowing and rotating with non-host crops and soybean with other SCN-resistance sources.
What could this mean for yield?
Using representative North Central Missouri conditions and the SCN Coalition Profit Checker, the estimated potential yield loss was 8.2%, or 4.5 bu/acre and $59/acre. Actual estimates depend on SCN population density, virulence (ability to reproduce on the soybean), field conditions, expected yield, and soybean price.
Don't rely on symptoms alone
Nematode problems can be easy to miss. A field with SCN can look healthy while yield is being lost. Stunting, yellowing, uneven growth, and poorly performing areas can indicate a significant problem; however, those symptoms are not specific to only nematodes.
Management starts with knowing what is in the field. For SCN, use resistant varieties, rotate resistance sources such as PI 88788 and Peking, and rotate with a nonhost crop such as corn. Nematode-protectant seed treatments may also provide early-season protection. Management options for other nematodes depend on the species and population density, and resistant varieties are not available for many of them.
Don't guess. Sample. Missouri soybean growers can currently submit up to four soil samples for free SCN egg counts through SCN Diagnostics, supported by the Missouri Soybean Merchandising Council. Visit SCN Diagnostics for more information.