Soybean Inoculant and Seed Treatment Interactions.

Soybean seed treatments are available to provide protection against various seedling pests and diseases. Direct contact of these seed treatment formulations with seed-applied Bradyrhizobium japonicum bacterial inoculants makes the resulting interaction of interest. The objective of this study was to investigate the possible interactions of various seed treatment formulations with soybean bacterial inoculants. Three popular inoculant products were applied to seed with different fungicide, insecticide, and nematicide treatments.  Seed treatments included ApronMaxx® RFC; ApronMaxx® RFC, Cruiser®; ApronMaxx® RFC, Cruiser®, Avicta®; and ApronMaxx® RFC, Poncho®/VOTiVO™. Inoculant products applied in conjunction with these seed treatments included Advanced Biological Marketing, ExcalibreSA™; Becker Underwood, Vault® HP; and Novozymes, Optimize® 400. Field experiments were set up in a randomized complete block design with four replications at four Kansas sites. Seed treatments did not prove to negatively affect soybean nodulation. There were significant differences in yield between treatments at the location which had been out of soybean production for 15 years. However, differences were small and the raw seed yielded as well or better than all treatment/inoculant combinations. At the other sites, yield was not significantly influenced by seed treatment and inoculant combinations. The results support the conclusion that seed treatment formulations did not significantly impact bacterial inoculant product performance, soybean nodulation, or yield.