Skip to main content
ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Aerial Application Technology Research » Research » Publications at this Location » Publication #335161

Title: The impact of spray adjuvants on solution physical properties and spray droplet size

item Fritz, Bradley - Brad
item Hoffmann, Wesley
item GIZOTTI-DE-MORAES, JESAELEN - University Of Nebraska
item GUERRERIO, MARCELLA - University Of Nebraska
item GOLUS, JEFF - University Of Nebraska
item KRUGER, G. R. - University Of Nebraska

Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2017
Publication Date: 3/5/2018
Citation: Fritz, B.K., Hoffmann, W.C., Gizotti-De-Moraes, J., Guerrerio, M., Golus, J., Kruger, G. 2018. The impact of spray adjuvants on solution physical properties and spray droplet size. Journal of ASTM International. 37:22-32.

Interpretive Summary: Controlling droplet size is one of the primary concerns faced by most aerial applicators prior to any application. While nozzle type effects are generally well established with ready guidance on selection and use, understanding of the impact that agrochemicals and secondary spray mix modifiers have on droplet size is limited. To further understand the role typical active pesticide products and spray solution modifiers play in the breakup of applied sprays and the longevity of evaporating droplets, 11 typical, real-world spray mixtures were tested for their physical properties, evaporation potential and droplet size. The results showed each product added to the spray solution had a significant impact on physical properties, particularly viscosity and spreading potential of deposited droplets, as well as, significant changes in droplet size with the different spray solutions.

Technical Abstract: Over the past several years, numerous anecdotes from aerial applicators have surfaced indicating observations of increased numbers of fine droplets seen in the applied spray clouds, usually associated with tank mixtures containing of crop oil concentrates and foliar fertilizers. Efforts were made to correlate surface tension and viscosity to spray droplet size under a variety of aerial application condition, but these efforts were unsuccessful. Additionally, spray mixtures were examined to compare relative evaporation rates. Researchers are encouraged to actively pursue this line of work. The addition of several adjuvants and foliar fertilizers were found to significantly affect spray droplet size so applicator should pay careful attention to spray tank composition to make safe and effective spray applications.