CLOMAZONE VOLATILIZATION UNDER VARYING ENVIRONMENTAL-CONDITIONS

Velvetleaf (Abutilon theophrasti Medik.) was used as a bioindicator to examine factors (temperature, soil moisture, soil incorporation) whic h might influence clomazone lorophenyl)methyl]-4,4-dimethyl-3-isoxazol idinone} volatilization. Young plants were periodically exposed to atm osphere inside boxes containing clomazone-treated soil. Exposed plants were returned to the greenhouse for 5 to 7 d, and new leaves were ass ayed for chlorophyll. Maximum chlorophyll inhibition occurred in velve tleaf exposed during the first 2 wk after clomazone application. Reduc tions in degree of bleaching were first observed in plants exposed in the treatments with lower soil moisture (2% moisture at 19 days after clomazone treatment, DAT; 9% at 42 DAT). The least amount of clomazone was measured in soils incubated in the 35 degrees C treatment, indica ting elevated temperatures enhanced volatilization, and may have contr ibuted to the increased chlorophyll content observed observed earlier than other temperatures. The effect of herbicide incorporation was not conclusive. Published by Elsevier Science Ltd