Soil release and bioefficacy of controlled release formulations of butachlor against jungle rice (Echinochloa colona)

An experiment was conducted during 2002 to study the release kinetics of butachlor from its polymeric controlled release formulations and their bioefficacy against jungle rice (Echinochloa colona). Controlled release formulations of herbicide butachlor (N-butoxy methyl-2-chloro-2",6" diethyl acetanilide) were prepared through its monolithic dispersion in polyvinyl chloride, polystyrene, thermokol and ethyl cellulose matrices. These controlled release formulations released butachlor in soil up to 80 days as compared to 30 days from its emulsifiable concentrate or granule. The release was diffusion-controlled with a half release time (T-0.5) of 20.09 to 42.10 days in different matrices. The controlled release formulations extended the residual toxicity of butachlor against Echinochloa colona up to 80 days after treatment compared to 32 days from the conventional formulations including a commercial emulsifiable concentrate and laboratory made granule.