The Soybean Cyst Nematode in Relation to Soil Fertility Characteristics in Illinois Farm Fields.

One of the constraints limiting soybean production in Illinois, the second producing state in the US, is the soybean cyst nematode (Heterodera glycines Ichinohe; SCN) pathogen. A survey of soybean producing fields across the state was conducted in 2010 and 2011 to evaluate the multivariate relationships between groups of SCN risk potential based on egg density and indicators of fertility (soil pH, CEC and the concentrations of SOM, P, K, Ca, and Mg). Using canonical discriminant analysis on categories of SCN groups, we identified simultaneous and consistent relationships between SCN groups and soil pH, exchangeable Mg, CEC, and SOM. The best prediction rate using this multivariate approach was found for the group with low SCN egg densities. These results illustrate the benefits of using multivariate approaches to understand the soil-SCN relationships in field conditions. Results suggest that agronomic management practices that holistically seek to maintain nutrient balance while maintaining soil pH < 6.42 and Mg concentrations > 400 mg kg^-1 soil can contribute to lower the risk associated with SCN and to the optimization of overall yield in Illinois.