Efficiency of reduced rates of 2,4-D in mixture with wood vinegar in weed control

Chemical control is the most efficient method in weed management. However, given the societal demand for reducing pesticide use and mitigating production costs, alternatives for reducing herbicide doses should be considered. Among the alternatives that can contribute to the sustainable management of weeds is wood vinegar, a bio-input that has several applications in agriculture. In light of this, the objective of this study was to evaluate the reduction of doses of 2,4-D herbicide by mixing it with wood vinegar (WV). The experiments were conducted in a greenhouse at the Campus of Engineering and Agricultural Sciences (CECA/UFAL). The experimental design was completely randomized in a 4x2 factorial scheme, with 4 herbicide-WV mixtures (Distilled water; 0.5 L ha-1 of 2,4-D + 1 L ha-1 of WV; 1 L ha-1 of 2,4-D + 0.5 L ha-1 of WV; and 1.5 L ha-1 of 2,4-D (recommended commercial dose), and the spray solution with water only and with mineral oil (0.5% v/v). The receptor plants were Crotalaria juncea, Senna obtusifolia, and Bidens spp., and each weed species constituted an experiment, where phytotoxicity scale, control (%), and relative dry mass (%) were evaluated. The reduction of 2,4-D doses was not effective in controlling Crotalaria juncea, which showed satisfactory control only at the commercial dose of the product with mineral oil. The species Senna obtusifolia and Bidens spp. were effectively controlled in all treatments of the experiments regardless of mineral oil.