Evaluation of Soybean Cyst Nematode Control with Pasteuria Nishizawae and the Effect of Management Practices on Biocontrol Efficacy.

Soybean Cyst Nematode (Heterodera glycines) is the most economically significant pathogen on soybean (Glycine max), causing over $1.5 billion dollars in damages annually. Pasteuria nishizawae, an endospore-forming soil bacterium, is an obligate parasite of soybean cyst nematodes (SCN). P. nishizawae has the potential to provide season-long control of SCN in the form of a seed treatment called Clariva^®Complete. In this study, we evaluated the efficacy of the active ingredient, P. nishizawae, for the management of SCN on soybean. The field design was a split-plot, randomized complete block design with sub-sampling for the 2014, 2015 and 2016 growing seasons. Each split-plot was randomly assigned a row spacing of 30-inch or 15-inch spacing. Each subplot within the split-plot was randomly assigned one of three seeding rates (75K seeds/acre, 150Kseeds/acre and 225K seeds/acre) and one of two seed treatments (Clariva^®Complete and CruiserMaxx^®/Vibrance^®). The 2014 and 2015 results showed no significant interaction between seed treatment and yield, but did show significant interactions between both seeding rate and row spacing with yield. The row spacing and location had significant effects on the SCN counts. No significant interaction was observed between the SCN count and the yield. Because the soybean variety used had PI88788 resistance, the Hg-type of the SCN population may not have been able to develop on soybeans with this source of resistance. This may have masked the effects of the seed treatment and prevented accurate evaluation of its efficacy. The 2016 field results will be processed prior to the conference and will be included in the poster.