The Specific Adhesional Forces of Aqueous Droplets on Crop Leaf Surfaces and Factors Influencing Them

Abstract

The specific adhesional force (Fs) of 0.2% aqueous solutions of surfactants (surface tension 28.5-72.5 mN m-1) on the surfaces of crop leaves and wax composition analogues were calculated with a new static approach. On rice, wheat, Job’s tears, cabbage and corn with wettability characteristics WCP-I, air-film was formed at high yx values to produce a large and almost the same 0a (maximal advancing contact-angle) and 6r(minimal receding contact-angle) (hence, a small or zero to make a small or zero Fs, but a large A6 abruptly appeared at 40–62 mN mr1of yi (hence, a large Fs), then Fsdecreased almost linearly to yi as yi declined further. On cotton, orange, cowpea, pimento, sweet potato and broad bean and on wax analogues with WCP-II, Fswas larger at higher yi values without formation of air film and decreased almost proportionally to ylmThe magnitude of Fsseemed to be controlled primarily by the surface tension yxof droplet and the microstructure of surface, and the difference in Fsamong the surfaces used was considered to be governed mainly by AO corresponding to the roughness of the microstructure. © 1993, Pesticide Science Society of Japan. All rights reserved.