Slow release formulation of herbicide metazachlor based on high molecular weight poly(lactic acid) submicro and microparticles

Abstract

Frequently used pre-emergent herbicide metazachlor was encapsulated into high molecular weight poly(lactic acid) particles, and its subsequent release and the effectivity of such formulations were investigated. Two sets of polymeric micro- and submicro particles, both with the theoretical metazachlor loading of 20%, 30%, and 40%, were prepared and characterized. Loading efficiency reached 80% for both types of particles. Release profiles were tested in vitro for the individual particle variants and were shown to have a bimodal profile with the initial fast burst release and much slower second phase. Finally, selected formulations were tested in vivo against target plants (field poppy and barnyard grass) and non-targets plants (mustard and rapeseed) and showed improved inhibition of target plants (about 30% higher for barnyard grass) and at the same time lower inhibition of non-target plants (rapeseed) in comparison with the identical dose of metazachlor alone. © 2019, Islamic Azad University (IAU).