FACTORS AFFECTING DROPLET SIZE, COVERAGE, AND WEED CONTROL WITH SHARPEN HERBICIDE
Gary Fellows, R Barbosa, R Vidrine, A Rhodes.
Contact: Gary Fellows
Technical Marketing Manager
26 Davis Drive
Research Triangle Park, NC 27709
Summary: Droplet size, number of spray droplets, and concentration of a herbicidal active ingredient within the droplet may impact efficacy of products sprayed aerially. Sharpen herbicide, active ingredient saflufenacil, is a new herbicide from BASF in the Kixor family of herbicides. Sharpen controls numerous broadleaf weeds, is an effective burn down product in front of many crops, and has an aerial label that allows total carrier volumes down to 3 gallons per acre. To work effectively, Sharpen requires adequate coverage on the weed leaf surface. Droplet size models have been developed to assist applicators with pattern testing and to optimize product performance. Aircraft speed, nozzle type and orifice size, spray pressure, nozzle deflection angle, and product(s) being sprayed affect droplet size and droplet number produced by each nozzle. Based on results from previous research and a desire to maximize efficacy of Sharpen herbicide, a study was conducted in June 2010 to compare expected droplet size with actual droplet size of water and a herbicide solution, to evaluate different boom set-ups for droplet size and droplet number, and to determine weed control with selected treatments of herbicide and boom set-ups. Based on this study, droplet size and droplet number are affected most by nozzle deflection angle, and secondarily by spray pressure. A 30º angle produced smaller and greater number of droplets than no deflection, and higher pressure created larger and fewer droplets. The expected size of droplets from a model was close to actual as long as a 5º or 30º deflection angle was included in the model. Droplet size produced with water only was similar to droplet size from the actual herbicide solution.