Soybean cyst nematodes cause between $800 million and $1 billion annually in crop losses in the United States, according the American Phytopathological Society. However, techniques are available to find soils that specifically suppress these microscopic roundworms, said Andreas Westphal, assistant professor of plant pathology. The female nematodes are white, lemon-shaped parasites that become dead brown shells filled with maturing eggs. Some soils have as yet not-understood characteristics that don't foster development of the pests.
Westphal, whose research focuses on soybean cyst nematodes and ways to thwart them, said that using nematode-suppressive soils is an easily implemented, environmentally friendly weapon in fighting the parasites, which are found worldwide in soybean-producing areas.
"Using plants bred to resist pests is not the complete answer, so it's important to find suppressive mechanisms," Westphal said. "Bio-control is much more desirable than using chemicals in order to limit damage to the environment."
In a paper published in the just-released March 2005 issue of the Journal of Nematology, Westphal summarizes the techniques for identifying soil that specifically suppresses soybean cyst nematodes. He also discusses how to use nematode-suppressive soils to battle the root-dwelling pests and the limitations of the techniques.
In previous research on a different cyst nematode, Westphal and his colleagues determined that mixing 1 percent to 10 percent of nematode-suppressive soil into the top layer of a soybean field plot effectively decreased nematode activity. In addition, they know that viability of plants and soil richness, moisture and temperature can affect how active and numerous soybean cyst nematodes are in particular fields.