Soybean Cyst Nematode - Agronomic Impact

Up 30% yield loss can occur because plants are producing fewer pods than they should. The effect of SCN on soybean yield is directly related to the numbers of nematodes feeding on the root system.

Severe stunting and yellowing due to SCN infection is visible in this field. However, significant yield loss can occur from SCN feeding without causing above-ground symptoms. Photo credit: Greg Tylka, Iowa State University

Below-ground symptoms

Root symptoms of SCN often go unrecognized. Often it is difficult to recognize if roots are stunted and have fewer nodules unless they are compared to uninfected soybean plants. Symptoms of SCN infection include:

• Dwarfed or stunted roots
• Fewer nitrogen-fixing nodules
• Increased susceptibility to attacks by other soil-borne plant pathogens

Above-ground symptoms

The above-ground symptoms of SCN range from nonexistent to severe depending on the age and vigor of the soybean plants, SCN numbers, soil fertility, moisture levels, and other environmental conditions.

Injury usually is more severe in light, sandy soils, but it also occurs in heavier soils. SCN damage is not always confined to smaller areas within a field. When fields are infested with SCN throughout; areas of stunted plants are not obvious.