EFFECT OF ENVIRONMENT ON WILD OAT (AVENA-FATUA) CONTROL WITH IMAZAMETHABENZ OR FENOXAPROP TANK-MIXED WITH ADDITIVES OR MCPA

Greenhouse and growth chamber experiments were conducted to determine the effect of soil moisture and temperature on the phytotoxicity in wi ld oat of imazamethabenz or fenoxaprop tank-mixed with certain additiv es or MCPA, The surfactants Agral 90 at 0.5% and Enhance at 0.5% incre ased imazamethabenz phytotoxicity under both moist and drought conditi ons. These surfactants had no significant effect on fenoxaprop phytoto xicity regardless of the soil moisture regimes. Fenoxaprop activity wa s increased by ammonium sulfate [(NH4)(2)SO4] at 1% but only under wel l watered conditions, Wild oat control with imazamethabenz was also sl ightly enhanced in a well watered regime by the addition of sodium bis ulfate (NaHSO4) at 0.13%. At high temperature (30/20 degrees C) and lo w temperature (10/5 degrees C), the phytotoxicity of imazamethabenz wa s increased when tank-mixed with Agral 90 at 0.25% or NaHSO4 at 0.13% compared with that when imazamethabenz was applied alone, if soil mois ture was adequate, There was no such increase under conditions of drou ght and high temperature, (NH4)(2)SO4 at 1% did not significantly affe ct imazamethabenz performance irrespective of temperature/soil moistur e conditions. The phytotoxicity to wild oat of imazamethabenz or fenox aprop was not changed by tank-mixing with MCPA isooctyl ester at 300 g a.i./ha, regardless of soil moisture levels, The reduced fenoxaprop p hytotoxicity in wild oat due to moisture stress was not readily allevi ated by the inclusion of selected additives or MCPA in the tank mixtur e.