Studies on wetting phenomena on plant leaf surfaces. 3: A retention model for droplets on solid surfaces

Abstract

Abstract To investigate the factors governing retention of pesticidal spray solutions on plant surfaces, a new retention model for droplets on solid surfaces has been introduced as magnified image where ΔΘ = Θ a – Θ r . The minimum sliding volumes (MiSV) of surfactant aqueous solutions (2 g litre −‐1 ; surface tensions; 28·5 – 72·5 mN m −‐1 ) on smooth surfaces of paraffin wax and polymer sheets were measured and the validity of the above retention equation was verified on combinations of these solutions and surfaces. A concept of the specific adhesional force ( F a ) of a droplet was defined as magnified image which was the maximum adhesional force on a unit length of the width of the contact circle of a droplet, and F a values of the solutions on the surfaces were compared. The predominant factors for droplet retention are discussed on the basis of this model.