The Effect of Polymeric, Ammonium Sulfate-Based Adjuvants on the Deposition of Glyphosate Spray Solutions

High molecular weight polymers have been shown to improve the efficacy of systemic herbicides such as glyphosate. The mode of activity of these polymeric adjuvants is not well understood. In this study a commercial polymer/ammonium sulfate (AMS)-based adjuvant was tested with commercial glyphosate formulations. The effect of the various treatments on the mass of spray deposited, droplet bounce, and droplet run-off was determined. The polymeric/AMS adjuvant was found to improve the deposition of the commercial glyphosate formulations in that: the loss of active due to spray drift was reduced, i.e., the mass of spray deposited was increased; droplet bounce of the spray solutions was reduced, i.e., droplet retention was improved; the polymeric/AMS adjuvant did not significantly affect the angle at which droplets were detached from leaves, therefore the adjuvant should not affect droplet run-off.