An Assessment of Polymeric Drift-Reduction Adjuvant Performance after Prolonged Exposure to Pump-Induced Shear

Emphasis has been placed on controlling the drift of synthetic auxin herbicides for postemergent applications of field weeds. This body of work evaluated a method for determining the performance of polymer-based drift-reduction adjuvants after repeated exposures to a pumping system. A parent solution of water with glyphosate and dicamba herbicides was combined separately with two different polyacrylamide adjuvants and a polysaccharide adjuvant for evaluation. Samples were collected after 0, 10, 25, and 50 passes through a closed-loop pumping system. The samples were then sprayed and measured within a spray-analysis wind-tunnel facility to evaluate the volume fraction of driftable droplets (less than or equal to 150 μm). All adjuvant products demonstrated an initial reduction in the driftable droplet content over the control. After 50 circulations through the pumping system, the two polyacrylamide products showed no difference in driftable content compared to the control. This was contrasted by the polysaccharide adjuvant retaining a reduction in driftable droplets throughout the test. Results concluded that this approach was an effective method for identifying possible deterioration of polymer-based drift-reduction adjuvants due to pump-induced shear.