Aplicação simultânea de dessecantes e boro no manejo de plantas daninhas e na nutrição mineral das culturas de soja e girassol

Two experiments were carried out to evaluate weed control in soybean (Glycine max) and sunflower (Helianthus annuus) pre-sowing by desiccant application alone or in combination with boron (B), as well as to evaluate the response of these crops to that micronutrient. The plots consisted of the desiccants glyphosate (1.44 kg a.e. ha-1), glyphosate potassium (2.48 kg a.i. ha-1), diuron (0.2 kg a.i. ha-1) plus paraquat (0.4 kg a.i.ha-1), paraquat (0.4 kg a.i. ha-1) in the soybean experiment. In the sunflower experiment, the plots consisted of glyphosate (0.54 kg a.e. ha-1), glyphosate (0.72 kg a.e. ha-1), glyphosate potassium (1.24 kg a.i. ha-1), paraquat (0.4 kg a.i.ha-1), glyphosate (0.72 kg a.e ha-1) plus flumioxazin (0.025 kg a.i. ha-1), glyphosate (0.72 kg a.e. ha-1) plus carfentrazone (0.02 kg a.i. ha-1). Both the experiments had two checks (handhoeing and weedy control) and the split-plots consisted of absence or presence of boron from boric acid [H3BO3 - 17% B], associated to the water carrier. The combination of herbicides with boron efficiently controlled the weeds, except for paraquat plus diuron. The application of boric acid in association with herbicides increased the content of this micronutrient in the soil and consequently in the soybean and sunflower leaves. The combined application of desiccants and boric acid appears to be suitable for controlling weeds and increases mineral nutrition of soybean and sunflower.