Controle de plantas daninhas com Cletodim e 2,4–D aplicados por um sistema de tanques e barras simples e duplas em diferentes taxas de aplicação

Abstract

Chemical weed management is essential for agricultural productivity and is widely based on the use of herbicides, particularly tank mixtures of herbicides and other products applied simultaneously. However, tank mixing may result in herbicide antagonism, reducing weed control efficacy. In addition, factors such as application rate and application technology directly influence herbicide performance, highlighting the importance of strategies that minimize incompatibilities. Therefore, this study aimed to evaluate the efficacy of the herbicides clethodim and 2,4-D applied during desiccation using a simple and dual tank and boom spraying system at different application rates. The experiment was conducted at the Araras Campus of the Federal University of Uberlândia, located in Monte Carmelo, Minas Gerais, Brazil, using a completely randomized design with seven treatments and four replications. Seven application systems were evaluated: tank-mixed herbicides applied with a single boom at application rates of 60 and 120 L ha⁻¹; two tanks with herbicides mixed directly at the boom at application rates of 60 and 120 L ha⁻¹; and two tanks with two independent booms (without herbicide mixing at any point in the spraying circuit) at three application rate combinations (60 L ha⁻¹ total, with 30 L ha⁻¹ applied per boom; 120 L ha⁻¹ total, with 60 L ha⁻¹ per boom; and 240 L ha⁻¹ total, with 120 L ha⁻¹ per boom). Spray solutions consisted of water, 2,4-D (Aminol®; 670 g a.e. ha⁻¹), clethodim (Poquer®; 108 g a.i. ha⁻¹), and mineral oil (Iharol Gold®; 0.5% v/v). Weed control was visually evaluated according to the Brazilian Weed Science Society (SBCPD, 1995) rating scale at 7, 14, and 21 days after application (DAA) for four representative weed species in the experimental area: two monocotyledonous species (Brachiaria decumbens and Digitaria horizontalis) and two dicotyledonous species (Alternanthera tenella and Richardia brasiliensis). Data were subjected to analysis of variance (ANOVA), and means were compared using Tukey’s test at the 5% significance level with R software®. The application system directly influenced weed control efficacy. Treatments that reduced (two tanks with boom mixing) or eliminated (two tanks with two independent booms) prior contact between clethodim and 2,4-D generally provided superior performance, particularly for the evaluated monocotyledonous species (Brachiaria decumbens and Digitaria horizontalis) and for the overall weed control at 14 and 21 DAA. The adoption of spraying technologies capable of preventing or minimizing prior mixing between ACCase-inhibiting and auxin-mimicking herbicides at application rates of 60 or 120 L ha⁻¹ represents a promising strategy to improve burndown application efficiency, contributing to more efficient, rational, and operationally feasible chemical weed management.