BackgroundSoybean cyst nematode (SCN) can devastate a soybean crop. Soybean cyst nematodes are small roundworms that attack soybean roots. Infected plants may be stunted or yellowed (Figure 1), and SCN may also cause yield losses of 15 to 30% with no readily visible above-ground symptoms. The life cycle of SCN is shown in Figure 2.

 Use of DataIKONOS satellite imagery was obtained of an SCN field trial in SE South Dakota. Imagery was collected on July 10, 2002 (Figure 3) and September 2, 2002. Pre-plant soil samples indicated SCN was present throughout the field, but at varying population densities. Individual plots were 30 ft wide and 700 ft long. Most of the entries in the trial were SCN-resistant varieties; however, an SCN-susceptible variety was replicated 3 times across the plot.

When the July IKONOS image was examined, areas of poor plant growth were observed (Figure 3). Subsequent field scouting confirmed that plants in these areas had symptoms associated with SCN and other stress factors including spring flooding and alkaline soil conditions.

Yield of the SCN susceptible variety was 20% less than the average yield of the SCN resistant varieties (35.4 vs. 44.0 bu/ac). Soybean cyst nematodes or other stress factors reduced yields in areas of poor plant growth (Figure 3). The resistant and susceptible varieties were sampled in a grid pattern for yield and SCN population densities. Currently, a statistical evaluation between yield, remote sensing and SCN population densities is being conducted.

 Economic and Environmental BenefitsSoybean cyst nematode is best managed through early detection, which can be achieved through remote sensing. Once SCN is identified, the use of resistant varieties and rotation with non-host crops such as corn, sunflower, small grains, alfalfa, and red clover can help reduce its negative impact. This will in turn lead to increased yield and profitability for the farmer.