Submitted to: Agricultural Aviation
Publication Type: Trade Journal
Publication Acceptance Date: December 4, 2003
Publication Date: January 1, 2004
Citation: Kirk, I.W. 2004. Performance of spray drift adjuvants. Agricultural Aviation. 31(1):25-27. Interpretive Summary: Drift of agricultural sprays is important to aerial applicators because of potential damage to off-target sites and possible associated litigation. Spray mix adjuvants are marketed for reducing spray drift. The primary effect of these adjuvants is increasing spray droplet size and reducing the amount of driftable fine droplets, which are the primary factors influencing spray drift. Simulated aerial spray applications were conducted in a wind tunnel using drift reduction adjuvants in the spray mix at rates and conditions typical of aerial spray application. The effectiveness of the adjuvants in increasing spray droplet size was different for different adjuvants. These wind tunnel studies with a blank spray mix and with a number of drift retardant adjuvants provided information that should aid in facilitating spray drift mitigation in commercial use. The amount of drift mitigation attained with drift reduction adjuvants is a matter that applicators can balance or optimize based on adjuvant performance and economics to achieve drift mitigation goals for a given application.
Technical Abstract: Numerous drift reduction adjuvants and spray deposition aids are available to aerial applicators. Since there are no product labeling or efficacy regulations for these adjuvants, applicators must rely on experience or information in the technical literature for evaluating their performance. Twelve new drift control adjuvants were selected for atomization studies in a wind tunnel to document their performance as applicable to aerial application. The adjuvants were mixed in a blank emulsifiable concentrate tank mix at their maximum recommended label rate for aerial application. Atomization data were collected with a laser spectrometer on the first and eighth passes through a gear pump. The eighth pass simulates the effect of shear breakdown and loss of effectiveness of the adjuvant from bypass and recirculation in the spray tank during application. Most of the adjuvants move the droplet spectra classification from Fine to Medium. The most effective adjuvant moved the droplet spectra classification from Fine to Coarse. This performance information will aid aerial applicators in selecting drift reduction adjuvants.