RESUMO
In Brazil, weed management in sugarcane fields is mainly done with the use of selective herbicide formulations. For many years, diuron+hexazinone was one of the main herbicide mixture formulations used in sugarcane. Later, sulfometuron-methyl was included in the same mixture, which was marketed as a new herbicide formulation for residual in-season weed control in sugarcane. The mixture diuron+hexazinone+sulfometuron-methyl has been widely used in commercial sugarcane fields in Brazil. However, recent field observations have shown that sugarcane plants at different growth stages varied in their phytotoxicity levels after treatment with diuron+hexazinone+sulfometuron-methyl. Greenhouse and laboratory studies were conducted to determine 14Csulfometuron-methyl absorption and translocation, as well as 14C distribution in sugarcane at two growth stages, 2 to 3 leaves and 5 to 6 leaves. 14Csulfometuron-methyl absorption by sugarcane did not differ between the two growth stages. Different patterns of 14C accumulation were observed, which may explain variations in sulfometuron-methyl phytotoxic responses observed in the field.
Assuntos
Herbicidas/farmacocinética , Saccharum/efeitos dos fármacos , Saccharum/crescimento & desenvolvimento , Compostos de Sulfonilureia/farmacocinética , Brasil , Radioisótopos de Carbono/farmacocinética , Saccharum/metabolismoRESUMO
When herbicides are applied in mixture, interactions among them could potentially promote changes in herbicide behavior in the soil. Thus, application mode (isolated or in mixture) and soil texture (sandy or clayey) were investigated in the total leaching of the commercial mixture diuron + hexazinone + sulfometuron-methyl, and of each isolated compound. Experiments in soil columns also evaluated the movement of each herbicide and mixtures across soil layers. In the sandy soil, the greatest total leaching was observed with hexazinone compared to diuron and sulfometuron. Most of the applied diuron remained at the top layer of the soil, indicating that this herbicide has low soil mobility. Overall, our results show that hexazinone has greater leaching potential and mobility along the soil profile compared to diuron and sulfometuron. Our data can be used in assessing the fate of diuron, hexazinone, and sulfometuron alone or in mixture on natural ecosystems, under different soil types and application modes.