ARS | Publication request: Spray characteristics affected by physical properties of adjuvants

Submitted to: National Agricultural Aviation Association Meeting
Publication Type: Proceedings
Publication Acceptance Date: December 12, 2008
Publication Date: December 12, 2008
Citation: Lan, Y., Fritz, B.K., Hoffmann, W.C., Bagley, W.E., Huang, Y., Martin, D.E., Lopez, J. 2008. Spray characteristics affected by physical properties of adjuvants. National Agricultural Aviation Association Meeting. Paper No. AA-08-005.

Interpretive Summary: Spray drift from the aerial application of pesticides has been recognized as a concern for the environment. Use of spray additives (adjuvants) is a tool that applicators can use to reduce spray drift, but there is limited technical literature on physical properties of new drift reduction adjuvants. Laboratory studies were conducted to measure the physical properties of selected adjuvants and determine their effect on spray characteristics. There were significantly different effects of spray additives on spray characteristics. The results show that aerial applicators can selectively use spray additives to change spray characteristics, thereby reducing drift and environmental impact in non-targeted areas.

Technical Abstract: Four drift adjuvants, Array, In-Place, Vector and Control, were tested and physical properties and spray spectrum parameters measured. Array had the highest conductivity, indicating a good potential for the electrostatic charging, and the highest shear viscosity. All adjuvants had very similar neutral pH (7.00 to 7.55) and specific gravity (0.987 to 0.997). In-Place had the highest dynamic surface tension (43.4 dyne/cm2) and Vector had the lowest (37.5 dyne/cm2). Array had the largest overall droplet size. Over all of the adjuvants, higher shear viscosity and conductivity generally corresponded with the larger droplet sizes. The opposite trends hold for changes in dynamic surface tension, with overall droplet size decreasing as dynamic surface tension increases.