Herbicide trial for Amaranthus palmeri control in maize. Second year results

Abstract

The trial is a continuation of the results shown at the 2022 Congress of the SEMh (carried out in 2020). In this experiment, carried out in 2021, the most effective active ingredients for the chemical control of Amarantus palmeri S. Wats. selected from the first trial were tested, in addition to incorporating new ones. In total, 13 herbicide treatments were tested, four in pre-sowing and nine in post-emergence in a randomized trial with four repetitions per treatment. Each elementary plot had an adjacent untreated check to mitigate the problem of irregular distribution, common in weeds, obtaining efficacy values in a more representative way. The A. palmeri density, cover and biomass were obtained 40 days after treatment (DAT). The results confirm that, under the trial conditions (direct sowing and prolonged emergence) a single application of any of the tested products would not be adequate to satisfactorily control this weed, not avoiding, in any case, new seed rain because the surviving plants were able to finish their cycle. Higher efficacy was also observed with pre-sowing products, as in the previous year's trial. Specifically, in this group, the product based on mesotrione + S-metolachlor was the best option, but with less than 94% biomass reduction at 40 DAT. Among the post-emergence treatments, the active ingredient dicamba once again stands out, although the mixture of this active ingredient with prosulfuron and the combined terbuthylazine + S-metolachlor also obtained similar results, but all of them with biomass reductions of less than 80%.