Plantas de cobertura como ferramenta de supressão e incremento no controle de buva - DOI:10.5039/agraria.v15i2a7522

: Integrated management practices should be recommended to avoid damage of glyphosate-resistant hairy fleabane [ Conyza bonariensis (L.) Cronquist] on the soybean crop. This study aimed to evaluate the effect of soil cover plants and chemical control on the glyphosate-resistant hairy fleabane. The field experiment was performed in a randomized block design, with treatments arranged in a factorial scheme (3x10), by using subdivided plots and four replicates. The main factor was composed by three types of soil cover (black oat, wheat and fallow), and on the subplots were evaluated the glyphosate+2,4-D amine in a tank-mix applied at 14 DBS (days before sowing) with sequential application of paraquat+diuron at 01 DBS; burndown performed at 07 DBS by using glyphosate alone or applied in a tank-mix with clorimuron-ethyl, diclosulan, imazethapyr, sulfentrazone, and flumioxazine; glyphosate alone applied at the V4 phenological development stage of the soybean, and control with no application on Roundup Ready® soybean. The hairy fleabane sensitivity to glyphosate was previously evaluated by the dose-response curve. The hairy fleabane demonstrated low sensibility to glyphosate, with 17280 g a.e. ha -1  needed for a 90% reduction of dry weight. Using wheat or black oat reduced the hairy fleabane population density by 95% and its plants height by 90% when compared to fallow, allowing the increased herbicide efficacy, regardless of the tank-mix. For the fallow, the tank-mix of glyphosate+2,4-D amine (1080+1340 g a.e. ha -1 ) herbicides with a sequential application of paraquat+diuron (200+100 g a.i. ha -1 ) provided a better control level during the evaluated period, protecting the yield potential.