Forward angled spray: a method for improving the efficacy of herbicides

摘要

It is challenging to obtain proper leaf wetting. An angled spray could overcome this impediment, but which spray angle is best suited to droplet size is still unknown. In an outdoor pot experiment, seven doses of cycloxydim and sethoxydim were sprayedwith single-orifice standard, anti-drift, and air induction (having a fine, medium, and extremely coarse spray quality, respectively) flat fan nozzles, using spray angles of 10°, 20° backward, 0° (vertical), 10°, 20°, 30°, 40°, 50°, and 60° forward relative to the direction of nozzle trajectory on wild barley at the three-leaf stage. Generally, the forward angled spray was better than the backward angled spray. With a standard flat fan nozzle, the forward angling of spray from 0° to 20° reduced the ED50 from 60.24 to 39.85 g a.i. ha~(-1) for cycloxydim and from 150.51 to 81.13 g a.i. ha~(-1) for sethoxydim. With an anti-drift flat fan nozzle, the forward angling of spray from 0° to 30° reduced the ED50 from 72.57 to 50.20 g a.i.. ha~(-1)for cycloxydim and from 181.94 to 104.51 g a.i. ha~(-1) for sethoxydim. With an air induction flat fan nozzle, the forward angling of spray from 0° to 40° reduced the ED_(50) from 102.96 to 45.52 g a.i.a.i. ha~(-1) for cycloxydim and from 209.91 to 92.80 g a.i. a.i. ha~(-1) for sethoxydim. More angling did not improve the efficacy of these herbicides. Our results revealed that larger spray droplets needed more spray angle than smaller spray droplets to achieve an equal control.