Dissipation of residues of MCPA and cyanazine in three forage grasses following post‐emergence application as a mixture in the establishment year

摘要

AbstractThe dissipation of MCPA and cyanazine in smooth bromebrass (Bromus inermis Leyss.), Russian wild ryegrass (Elymus junceus Ficsch.) and intermediate wheatgrass (Agropyron intermedium) (Host) Beauv.) grown at three sites in western Canada was monitored for an eight‐week period following post‐emergence application of the herbicides as a mixture at 0.56 + 0.28 kg ha −1. The grasses were in the two‐ to six‐leaf stage at the time of application. MCPA, as its methyl ester, was detected using electrolytic conductivity detection whereas N‐specific alkali‐ionization detection was used for cyanazine. Foliar MCPA residues decreased more rapidly than those of cyanazine. At 56 days after application, MCPA residues were non‐detectable in all three grass species at all sites. Corresponding residues of cyanazine were of the order of the limit of quantification (0.02 m