Skip to main content
ARS Home » Midwest Area » Wooster, Ohio » Application Technology Research » Research » Publications at this Location » Publication #83672
Title: USING A VIDEOGRAPHIC SYSTEM TO ASSESS SPRAY DROPLET IMPACTION AND REFLECTION FROM LEAF AND ARTIFICAL SURFACES

Author
item REICHARD, DONALD - USDA-ARS-ATRU (DECEASED)
item COOPER, JANE - OARDC-OSU
item BUKOVAC, M - MICH STATE UNIV
item Fox, Robert

Submitted to: Pesticide Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Application of foliar pesticide sprays is a complex process that includes atomization, transport, impaction, retention and possible uptake by the plant which all influence pest control.Droplet retention on a plant surface is only one stage in the application process, but it is critical because only retained spray is useful for crop protection while reflected spray results in economic loss and contributes to environmental contamination. Whether a droplet is retained or reflected by a plant surface depends on the properties of the spray solution (dynamic surface tension, viscosity), spray pattern (droplet size, velocity), and the surface morphology (pubescence, venation, fine structure) and chemistry of surface functional groups of the target. In this study, we used a video motion analysis system in conjunction with two different mono-disperse droplet generators to develop techniques to view and quantify droplet reflection. We measured differences in reflection due to many parameters, including plant species, leaf location and age, droplet velocity and size, along with surfactant type and concentration. The data highlight the fact that differences in reflection usually followed a trend, but that actual results were often species or surfactant specific. These techniques were used to obtain more sharply defined differences in droplet reflection than had been previously made. An accurate measure of rebound is important to formulation chemists who determine the effects of the proposed surfactants and other adjuvants on the reflection of sample sprays.

Technical Abstract: A video motion analysis system was used in conjunction with two different mono-disperse droplet generators to quantify droplet impaction and any consequent reflection. Three techniques are described for assessing the deformation at impaction of a single droplet on an artificial surface, and reflection of both single droplets and droplets in a spray cloud, from a variety of plant surfaces. Determination of droplet in-flight diameter, dimensions of impacting droplets, droplet velocity prior to and immediately after impaction, and reflection height and number were all possible depending upon the technique selected. The results presented are intended to indicate what can be achieved, rather than as studies in themselves.