Effect of Venturi-Type Nozzles and Application Volume on Postemergence Herbicide Efficacy1

Abstract

Field studies were conducted to compare venturi-type nozzles to a fan nozzle with respect to the efficacy of postemergence herbicides applied to common cocklebur and broadleaf signalgrass. Spray solutions of glufosinate, glyphosate, and paraquat were applied through all combinations of three nozzles and two application volumes. Venturi nozzles were a Delavan Raindrop Ultra (RU) and a Spraying Systems AI Teejet (AI). A Spraying Systems XR Teejet (XR) fan nozzle was included as a standard. Previous work indicated droplet size spectra differed among these nozzles. There was a difference in common cocklebur control among nozzles (AI = XR > RU), although control was at least 90% for all nozzles. Herbicide choice had a greater effect on broadleaf signalgrass control than nozzle type. Broadleaf signalgrass control differed among herbicides (glufosinate = paraquat > glyphosate) and among nozzles (AI = XR > RU). Herbicide performance varied between nozzles (AI > RU), but the AI nozzle was as effective as the XR fan nozzle.Nomenclature: Glufosinate; glyphosate; paraquat; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash #3 BRAPP; common cocklebur, Xanthium strumarium (L.) # XANST.Additional index words: Drift.Abbreviations: AI, Spraying Systems AI Teejet; RU, Delavan Raindrop Ultra; VMD, volume median diameter; WAT, weeks after treatment; XR, Spraying Systems XR Teejet.