| dc.description.abstract | Weed management is an essential component of production agriculture. While many weed management methods exist today, chemical practices have proven to be the most efficient and are the most widely adopted methods. The objectives of this research were to: 1) maintain glufosinate weed control activity using a larger than recommended ultra-coarse spray droplet spectrum through utilizing commercially available adjuvants and 2) improve the activity of commercial glufosinate formulations in terms of increased weed control and shortened rainfast interval. Field trials were conducted to identify adjuvants that would maintain glufosinate weed control activity at an ultra coarse spray quality. Commercially available adjuvants representing acidic ammonium sulfate (AMS) replacements, deposition aids, and organosilicone surfactants were applied with a medium and ultra coarse spray quality. The negative impact of an ultra coarse spray quality on glufosinate activity was only observed when utilizing only AMS in the spray solution, and these impacts were dependent on the treated species. While there were individual additives that provided enhanced weed control of certain species, no specific adjuvant class improved Liberty 280 SL efficacy consistently throughout the tested species. To determine which adjuvants enhanced glufosinate weed control efficacy and rainfastness in a commercial formulation, trials were conducted with sublethal rates using a simplified glufosinate formulation (GFA 196 SL), which contained a lower adjuvant load. Candidates of three adjuvant classes, polymers, surfactants, and oils, were tested. The additives were evaluated for effect on efficacy in field trials, and their effect on uptake and rainfastness were evaluated in radiolabeled laboratory work, as well as in simulated rainfall environments in both the field and greenhouse. Overall, the polymer Kuraray provided the best enhancement of glufosinate activity for both efficacy and rainfast characteristics. Oils were the only class of adjuvant to consistently improve glufosinate activity in these trials. The included oils provided the most consistent enhancement of glufosinate in the greenhouse rainfast trial by reducing the rainfast period by over 50% compared to GFA 196 SL alone and improving glufosinate uptake into common lambsquarters. Further research is needed to consider the feasibility of directly formulating these additives into a future glufosinate formulation. | en_US |
