Growth and Competitiveness of Sulfonyhirea-Resistant and -Susceptible Kochia (Kochia scoparia)

Abstract

Growth, competitiveness, and fecundity differences between resistant (R) and susceptible (S) biotypes affect management strategies. This greenhouse research examines growth, competitiveness, and fecundity of chlorsulfuron-resistant (R) and -susceptible (S) kochia collected from North Dakota and Kansas. In noncompetitive studies, sulfonylurea R and S kochia biotypes from Kansas and North Dakota had similar growth rates and seed production. All biotypes produced about 12000 seeds per plant. Competitiveness of R and S biotypes from Kansas was similar. Interbiotype competition reduced R and S plant biomass more than intrabiotype competition. The relative competitiveness of the R and S biotypes was 0.75 and 0.85, respectively. The resistance trait did not reduce growth, seed production, and competitiveness of R compared to S kochia in greenhouse studies.