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Title: Inflence of air shear and adjuvants on spray atomization

Author
item Fritz, Bradley - Brad
item Hoffmann, Wesley
item BAGLEY, WILLIAM - Wilbur-Ellis Company
item KRUGER, GREG - University Of Nebraska
item CZACZYK, ZBIGNIEW - Poznan University Of Life Sciences
item HENRY, RYAN - University Of Nebraska

Submitted to: Journal of ASTM International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2013
Publication Date: 6/18/2014
Citation: Fritz, B.K., Hoffmann, W.C., Bagley, W.E., Kruger, G., Czaczyk, Z., Henry, R. 2014. Inflence of air shear and adjuvants on spray atomization. In: Sesa, C., editor. Pesticide Formulation and Delivery Systems: 33rd Volume, Sustainability: Contributions from Formulation Technology, STP 1569. ASTM International: West Conshohocken, PA. p. 139-150. doi: 10.1520/STP156920120131.

Interpretive Summary: Droplet size is critical to maximizing pesticide efficacy and mitigating off-target movement, and correct selection and adjustment of nozzles and application equipment, as well as the use of adjuvants, can aid in this process. However, in aerial applications air shear tends to be the dominant factor influencing spray droplet size. The objective of this work was to take a step-wise approach to examine the influence of both adjuvant type and airspeed on droplet size in the presence of a formulated herbicide (glyphosate). While the results show that the use of the tested spray adjuvants affect droplet size, as airspeed increased the differences in resulting droplet size between the adjuvants decrease. Though a number of tested combinations of adjuvant, nozzle and airspeed did not necessarily increase droplet size or reduce the number of fine droplets, they may have a place in aerial application. Other benefits, including retention and reduced evaporation that could not be measured as part of this study, can also be critical to the success of an application. For any pesticide application, applicators should read and follow product label instruction while being cognizant that the decisions they make, be it nozzle selection or product, will affect droplet size.

Technical Abstract: Droplet size is critical to maximizing pesticide efficacy and mitigating off-target movement and correct selection and adjustment of nozzles and application equipment, as well as the use of adjuvants can aid in this process. However, in aerial applications air shear tends to be the dominate factor influencing spray droplet size. The objective of this work was to take a step-wise approach to examine the influence of both adjuvant type and airspeed on droplet size in the presence of a formulated glyphosate product. While the results show that the use of the spray adjuvants tested do play a role in droplet size, as airspeed increases the differences between the adjuvants tested decrease. Though a droplet number of the adjuvant, nozzle and airspeed combinations tested did not necessarily increase droplet size or reduce fines, this does not indicate that they do not have a place in aerial application. Other benefits, including retention and reduced evaporation that could not be measured as part of this study, can also be critical to an application’s success. For any pesticide application, applicators should read and follow product label instructions while being cognizant that the decisions they make, be it nozzle selection or products, will affect droplet size.