Herbicide selectivity for conventional maize hybrid

Abstract

The cultivation of conventional maize in refuge areas is important for preserving Bt technology and serving specific markets with greater added value to the grains. Therefore, research aimed at chemical weed control must also continue to be directed to conventional maize hybrids. The objective was to evaluate the selectivity of herbicides applied in pre- and post-emergence of a conventional maize hybrid cultivated in the Cerrado biome of Brazil. Two field experiments were set up, one in summer and the other in second season. The treatments were composed of eleven herbicide treatments, whose doses are presented in g ha^-1 of active ingredient: S-metolachlor (1,440), S-metolachlor (1,680), mesotrione + atrazine (115.2 + 2,000), mesotrione + atrazine (192 + 2,000), tembotrione + atrazine (75.6 + 2,000), tembotrione + atrazine (100.8 + 2,000), nicosulfuron + atrazine (16 + 2,000), nicosulfuron + atrazine (24 + 2,000), [mesotrione + atrazine] ([120 + 1,200]), sequential application of [mesotrione + atrazine] ([60 + 600]), atrazine (2,000), plus a weeded control. Regardless of the experiment, all herbicides applied pre- and post-emergence of maize led to low percentages of phytointoxication. In both experiments, none of the treatments caused reductions in crop stand, confirming the absence of plant mortality due to the application of herbicides. Plant tipping/lodging was seen in summer maize, with no treatment effect. Maize 100-grain mass and yield did not change as a result of the application of herbicides in pre- and post-emergence of the crop. All herbicide treatments evaluated showed selectivity for the conventional maize hybrid.