Improving Pesticide Applications Through Understanding of Spray Droplet Spectra in the Winfield Spray Analysis System.

The Winfield Spray Analysis System, which uses laser diffraction in a low speed wind tunnel to measure droplet size of agricultural sprays, has been fully operational for nearly two years. In this time we have tested more than 800 spray nozzles with a variety of pesticides and adjuvants. We have gained numerous insights into product development, drift reduction technologies, droplet size distribution, nozzle effects, and pesticide interactions. The Winfield Spray Analysis System uses a Sympatec HELOS-KR laser diffraction particle size sensor to sample the full width of a spray pattern. The fully enclosed low speed wind tunnel has air flow concurrent with the spray direction to prevent repeated sampling of small droplets. The Winfield Spray Analysis System can safely test active pesticide formulations, a limitation for many laboratories. Sprays can be classified as fine, medium, coarse, etc…using the volume median diameter (D_V0.5), or diameter at which 50% of the volume includes smaller droplets, as well as the D_V0.1 and D_V0.9 (10% and 90%, respectively) The cumulative percent of spray volume comprising droplets smaller than a value of interest can also be measured, i.e. driftable fines (< 105 μm)_. Research with the Winfield Spray Analysis System has demonstrated differences in spray droplet spectra between nozzle types within the same size classification. Additionally, spray droplet spectra may be influenced by active pesticide formulation and adjuvants. The Winfield Spray Analysis System provides insight and knowledge to growers, retailers, custom applicators, and researchers. We aim to educate stakeholders in order to improve spray applications using existing and novel technologies to reduce drift while maintaining efficacy.