In recent years, contact herbicides have been sprayed, with reduced spray volumes, using spray nozzles that work at low pressures. To evaluate the flat fan spray nozzles of Teejet series XR, DG, TT and AI operated at different pressures, it was conducted an experiment for hairy beggar ticks (Bidens spp.) control. The experiment was carried out in Passo Fundo Municipality (Brazil), using bentazon contact herbicide in a soybean culture. The XR 110015, DG 110015 and TT 110015 nozzles were operated with pressure levels of 100; 200 and 300 kPa, and the AI 110015 nozzle with pressures of 200; 300 and 400 kPa. It was evaluated the hairy beggar ticks control at 7; 14 and 21 days after treatment and the grain yield of soybean. The AI 110015 nozzle showed inappropriate for this herbicide application in all evaluated pressures. Pressure of 100 kPa for the series XR, DG and TT, nozzles, were inadequate to use for contact post emergence herbicide application. All evaluated nozzles showed improved efficiency with the increase of pressure.
pesticides spray technology; bentazon; Bidens spp
