EFFECT OF ORGANOSILICONE-BASED ADJUVANTS ON HERBICIDE EFFICACY

Laboratory and field experiments were conducted to evaluate the effica cy of the post-emergence herbicides, fluazifop-P-butyl, glyphosate-iso propyl-ammonium, paraquat, and glyphosate-trimesium (sulfosate) as inf luenced by organosilicone-based adjuvants, 'Dyne-Amic' and 'Kinetic'. Conventional adjuvants 'Agri-Dex' and 'Induce' were included in all ex periments for comparison. The experimental plots were naturally infest ed with bahiagrass, camphorweed, common lambsquarters, Florida pusley, Jerusalem oak, hairy beggarticks, pigweed, and teaweed. Herbicides we re 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 increa sing 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 lit er-1 in increasing the efficacy of herbicides on the weeds studied. Pa raquat tank-mixtures with the pre-emergence herbicides bromacil and di uron were more effective when applied at a spray volume of 280 liter h a-1 than at 140 liter ha-1. Fluazifop-P-butyl and glyphosate-isopropyl ammonium were more effective at 186 than at 93 liter ha-1. Addition of 'Kinetic' or 'Induce' to the herbicide spray solution had no effect o n pH, but fluazifop-P-butyl reduced pH to 5.1 or increased it to 7.7 w hen added to the 93 and 186 liter ha-1 preparations, respectively. Gly phosate-isopropyl-ammonium reduced pH to 5.0 at the lower, but had lit tle effect on pH at the higher rate. Reduction in static surface tensi on and contact angle was greater with organosilicone-based adjuvants t han with conventional adjuvants.