Controle de buva (conyza bonariensis) com diferentes herbicidas, momentos de aplicação e uso de misturas de insumos agrícolas em soja com tecnologia Enlist®

Abstract

Weeds limit soybean production by competing for essential resources such as water, light, and nutrients. Therefore, chemical control should be based on knowledge of the species present, their potential to damage the crop, and the available management options, especially herbicides. In this context, this research aimed to evaluate the optimal timing for the control of hairy fleabane (Conyza bonariensis), as well as the effects of single or tank-mixed applications agricultural inputs on selectivity, physiological characteristics, and grain yield components of soybean with Enlist® technology. In the three field experiments conducted, the objectives were, respectively: (a) to evaluate the efficacy and selectivity of herbicides applied before and after soybean sowing for the control of hairy fleabane; (b) to assess selectivity, effects on physiological characteristics, and grain yield components of soybean with Enlist® technology when herbicides were applied alone or tank-mixed with agricultural inputs; and (c) to evaluate selectivity, effects on physiological characteristics, and grain yield components of soybean with Enlist® technology when insecticides, fungicides, and herbicides were applied alone or tank-mixed. The experiments were arranged in a randomized block design with four replications. The evaluated variables included hairy fleabane control, soybean phytotoxicity, and the effects of these factors on gas exchange and grain yield components of the crop, cultivar Vênus. The first study showed that treatments with mesotrione + atrazine, dicamba, 2,4-D, and atrazine + simazine applied in early management, combined with desiccation using diquat + saflufenacil and post-emergence application of 2,4-D choline + glyphosate, ensured effective control of hairy fleabane and higher grain yield. The second study demonstrated that the tank mixture of glyphosate+2,4-D choline with agricultural inputs increased phytotoxicity and reduced yield, especially in sequential applications (V3+V6), whereas the isolated use of agricultural inputs promoted an average increase of 3.16% in soybean grain yield. The third study showed that the application of glyphosate + ammonium glufosinate + 2,4-D choline + benzovindiflupyr + prothioconazole + thiamethoxam + lambda-cyhalothrin mixed in the spray tank resulted in the highest phytotoxicity to soybean and, at the same time, was one of the treatments that provided the highest grain yield. The use of different herbicides in early management, desiccation, and post-sowing soybean applications becomes an alternative for controlling hairy fleabane, resulting in high soybean grain yields. Herbicide mixtures with agricultural inputs, especially in sequential applications, increased phytotoxicity and reduced soybean grain yield. Applications of fungicides, herbicides, and insecticides tank-mixed increased phytotoxicity in soybean but did not necessarily compromise grain yield, highlighting the physiological and productive compensation capacity of Enlist® soybean.