Mesotrione – a New Herbicide for Weed Control in Maize

Six field trials were conducted over three growing seasons to evaluate both pre-and post-emergence applications of the recently developed herbicide mesotrione, for weed control in maize. As a pre-emergence treatment it provided excellent control of broadleaf weeds (>99% reduction in dry matter) but was poor on grass weeds (ca 80% reduction). However, its combination with atrazine, s-metolachlor or acetochlor provided >93% reduction in grass and broadleaf weed dry matter. Applications of mesotrione post-emergence were very effective on broadleaf weeds (>94%) but less so on grass weeds (ca 85%) although several adjuvant combinations improved the efficacy against annual grass weeds. A number of herbicide combinations were demonstrated to be effective for postemergence weed control. Mesotrione did not cause any apparent damage to maize crops in any trial and grain yields were not significantly different from the standard treatments. Recommended rates for post-emergence use of mesotrione will be 72–96 g/ha depending on soil type.