The efficacy of sulfosulfuron on spontaneous barley as affected by the type, size, and outlet design of flat fan nozzle

Sulfosulfuron, when applied at a label-increased rate, can control spontaneous barley (Hordeum spontaneum K. Koch) in wheat. For optimization, a dose-response bioassay was conducted on three-leaf spontaneous barley plants treated with six sulfosulfuron doses (0, 6.75, 13.5, 27, 40, and 80 g a.i. ha -1) under the wind speed of 0 and 6 m s-1. Each of the doses was sprayed with three nozzle types (standard, anti-drift, and air induction), each with three outlet designs (single, dual, and triplet flat fan) at three nozzle sizes (02, 03, and 04, delivering 210, 315, and 420 L ha -1, respectively). Moreover, at 0 m s-1 wind, vertically and horizontally oriented water -sensitive papers (WSP) were treated with a dose of 40 g a.i. ha- 1 sulfosulfuron. The horizontally-oriented WSP wetted less as the droplet size produced by the nozzles increased. The vertically-oriented WSP wetted more as the outlet number of nozzles increased. When the ED90 values averaged over the nozzle type at 0 m s-1 wind, the standard nozzle type had the best performance, followed by the anti-drift nozzle type and then the air induction nozzle type, while this ranking reversed at 6 m s-1 wind. Moreover, the optimized rates were achieved by increasing the spray volume and the outlet number of all nozzle types at both wind speeds. At 0 m s-1 wind, the standard triplet flat fan nozzle delivering 420 L ha- 1 was the best with a low endo-drift. At 6 m s-1 wind, the air induction triplet flat fan nozzle delivering 420 L ha- 1 was the best nozzle having a low exo-drift.

Automated summary

The study found that increasing the dose and spray volume of sulfosulfuron, as well as using appropriate nozzle types and outlet designs, can optimize the control of spontaneous barley in wheat.