Canola (<i>Brassica napus</i>) Response to Simulated Sprayer Contamination with Thifensulfuron and Thifensulfuron:Tribenuron (2:1)

Abstract

Greenhouse and field studies were conducted in 1992 and 1993 in Manitoba and Saskatchewan to determine the effect of simulated sprayer contamination with thifensulfuron and thifensulfuron:tribenuron (2:1) on canola. In greenhouse studies, canola was more sensitive to tribenuron and thifensulfuron:tribenuron (2:1) than thifensulfuron. Thifensulfuron was more phytotoxic to canola when applied with Merge (50% surfactant blend and 50% petroleum hydrocarbon solvents) than with Agral 90 (non-ionic spreader and activator) at recommended adjuvant concentrations {1% and 0.2% (v/v), respectively}. In the field, canola injury tended to be more severe when thifensulfuron was applied with Merge than with Agral 90, but yields did not differ significantly between adjuvants, Thifensulfuron and thifensulfuron:tribenuron (2:1) at rates as low as 0.1 g ai/ha severely injured canola, delayed flowering, and reduced yield and subsequent seed germination. Thifensulfuron at 0.1 to 0.15 g/ha in mixtures with sethoxydim plus Merge reduced yields up to 61%.