Flucarbazone-sodium (EverestŪ) is used in Western Canada as a post-emergence herbicide for the control of wild oats (Avena fatua) and green foxtail (Setaria viridis) in spring wheat (Triticum aestivum). It belongs to a group of herbicides that contain an active ingredient that interferes with an important metabolic pathway (i.e., branched-chain amino acid synthesis) unique to plants and microorganisms. Due to the residual nature of flucarbazone and its increasing usage in crop rotation preceding pea production in Western Canada, the negative impact of the herbicide on legume-rhizobia symbiosis is a concern. Our objective was to determine if the herbicide residue may influence the effectiveness of inoculation in field pea production. In order to simulate flucarbazone carryover during crop rotation, wheat was grown in year 1 and treated with three rates of flucarbazone-sodium (0, 20, 30g ai ha-1) with 30g ai ha-1 being the recommended application rate. In year 2, these plots were seeded to field pea (cv. Mozart) inoculated with Rhizobium leguminosarum bv. viciae. The origin of nodule occupants (i.e. inoculum or the native strains present in soil) was determined by recovering rhizobia from nodule samples and conducting restriction fragment length polymorphism (RFLP) analysis on PCR amplified rhizobial DNA products.