EFICÁCIA DE ATRAZINA EM COMPARAÇÃO COM TERBUTILAZINA NO CONTROLE DE PLANTAS DANINHAS NA CULTURA DO MILHO (Zea mays L.)

Abstract

This study evaluated, under field conditions, the comparative efficacy of the herbicides atrazine and terbuthylazine in weed management in maize (Zea mays L.), as well as the performance of mesotrione applied alone or in mixture with atrazine, considering pre- and post-emergence placements. The guiding research question was: which products and doses ensure efficient control between 7 and 28 days after application (DAA), with agronomic safety and environmental coherence? The experiment was conducted in a randomised complete block design with 14 treatments (untreated control; five doses of atrazine; six doses of terbuthylazine; mesotrione alone; mesotrione + atrazine), with visual control assessments (0–100%) performed at 7, 14, 21 and 28 DAA. Data were analysed by ANOVA and Tukey’s test (5%), complemented by Dose versus Time response surface modelling, calculation of the area under the curve (AUC) as a cumulative performance metric (%·day), and principal component analysis (PCA). In pre-emergence, a progressive and dose-dependent response was observed for the triazines, without universal convergence to the 100% efficacy ceiling at 28 DAA, showing species-specific performance and greater multivariate variability. In post-emergence, mesotrione (alone or in mixture) exhibited faster action and convergence to the efficacy ceiling (≈99.75% at 28 DAA), whereas atrazine required higher doses to approach 95% control and terbuthylazine showed intermediate performance. The AUC analysis confirmed the cumulative superiority of the HPPD mechanism under post-emergence conditions. No maize injury was observed under any evaluated condition, and grain yield did not differ among treatments. It is concluded that rational weed management should integrate strategic placement (pre-emergence as a residual base; post-emergence as a high-impact foliar window), rotation of modes of action, and dose adjustment according to species and environmental conditions, thereby ensuring high agronomic performance with environmental responsibility.