Soybean Cyst Nematode Control with Pasteuria nishizawae Under Different Management Practices

Soybean cyst nematodes (SCN, Heterodera glycines Ichinohe) are one of the most devastating pathogens of soybean [Glycine max (L.) Merr.], causing more than US$1.5 billion in yield losses annually. The current control measures of crop rotation and genetic resistance are not sufficient to manage SCN population densities. In this study, we evaluated the efficacy of a bacterial biological control agent of SCN, called Pasteuria nishizawae, found in the Clariva Complete seed treatment (Syngenta, Syngenta Headquarters, Wilmington, DE) and its interaction with row spacing and seeding rate against Cruiser Maxx Vibrance. We evaluated these seed treatments at three seeding rates (185,250, 370,500 and 555,750 seeds ha(-1)) and two row spacings (38 and 76 cm) to determine the effect of the biocontrol component on soybean yield and SCN reproduction and its interaction with management practices. We observed similar soybean yield and SCN reproductive factors for soybean treated with either the Clariva Complete or Cruiser Maxx Vibrance seed treatment (Syngenta, Syngenta Headquarters, Wilmington, DE). In 2014 and 2015, soybean yield increased with each increase in seeding rate and decrease in row spacing. The SCN reproductive factor response was variable among factors. Based on our findings the most economically advantageous combination of seed treatment, row spacing, and seeding rate was Cruiser Maxx Vibrance planted in 38 cm rows and 185,250 seeds ha(-1). Overall, the manipulation of row spacing and seeding rate resulted in more significant differences in soybean yield and SCN reproduction than the biological control seed treatment and should be considered when planting into fields infested with SCN.