Ivan Kirk
Agricultural Research Service, USDA, Retired

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 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.
Key words: Aircraft, nozzles, drift, spray, droplet size, adjuvant, wind tunnel