Residues of the Herbicides MCPA and Bromoxynil in Postemergence-Treated Triticale (×Triticosecale)

In a two-year study involving two sites in western Canada, the dissipation of bromoxynil octanoate alone at 0.35 or 0.42 kg phenol equivalent (pe)/ha and the tank mixture of MCPAiso-octyl ester at 0.28 kg ae/ha plus bromoxynil octanoate at 0.28 kg pe/ha was monitored in postemergence-treated triticale. Initial foliar residues on the day after application (three- to four-leaf stage of the crop) were of the order of 14 and 5 mg/kg for MCPA and bromoxynil, respectively. Residues of both herbicides decreased to less than the limit of quantification (0.025 mg/kg) of the analytical method 21 d after application. At crop maturity, herbicide residues were non-detectable in the straw and seed. There was little or no effect on the dissipation of bromoxynil residues due to tank mixing with MCPA.