Effect of organosilicone‐based adjuvants on herbicide efficacy

Laboratory and field experiments were conducted to evaluate the efficacy of the post‐emergence herbicides, fluazifop‐P‐butyl, glyphosate‐isopropyl‐ammonium, paraquat, and glyphosate‐trimesium (sulfosate) as influenced by organosilicone‐based adjuvants, ‚Dyne‐Amic’︁ and ‚Kinetic’︁. Conventional adjuvants ‚Agri‐Dex’︁ and ‚Induce’︁ were included in all experiments for comparison. The experimental plots were naturally infested with bahiagrass, camphorweed, common lambsquarters, Florida pusley, Jerusalem oak, hairy beggarticks, pigweed, and teaweed. Herbicides were applied alone or in combination with ‚Dyne‐Amic’︁, ‚Kinetic’︁, ‚Agri‐dex’︁, or ‚Induce’︁ using a tractor‐mounted boom sprayer. ‚Dyne‐Amic’︁ (2.5 ml liter −1 ) was as effective as ‚Agri‐dex (10 ml liter −1 ) in increasing the efficacy of herbicides on grass and broadleaf weeds studied. ‚Kinetic’︁ at 2.5 ml liter −1 was as effective as ‚Induce’︁ at 2.5 ml liter −1 in increasing the efficacy of herbicides on the weeds studied. Paraquat tank‐mixtures with the pre‐emergence herbicides bromacil and diuron were more effective when applied at a spray volume of 280 liter ha −1 than at 140 liter ha −1 . Fluazifop‐P‐butyl and glyphosate‐isopropylammonium were more effective at 186 than at 93 liter ha −1 . Addition of ‚Kinetic’︁ or ‚Induce’︁ to the herbicide spray solution had no effect on p H , but fluazifop‐P‐butyl reduced p H to 5.1 or increased it to 7.7 when added to the 93 and 186 liter ha −1 preparations, respectively. Glyphosate‐isopropylammonium reduced p H to 5.0 at the lower, but had little effect on p H at the higher rate. Reduction in static surface tension and contact angle was greater with organosilicone‐based adjuvants than with conventional adjuvants.