WETTING PROPERTY REPRESENTATION OF PESTICIDES ON THE CROP LEAF SURFACES

The research on the representation of wetting property of pesticide droplets applied on crop leaf surfaces would contribute to the improvement of pesticides applications. To further understand the wetting property of pesticides on crop leaves with all the aspects, relevant experiments were carried out. Firstly, the surface tension of validamycin aqueous solution with different concentrations was measured. As a result, critical micelle concentration of adjuvants in validamycin aqueous solution was 3.6364 g/l. Afterwards, the static contact angle of validamycin aqueous solution on crop leaf surfaces was obtained. It was obvious that when the concentration of validamycin aqueous solution was 3.6364 g/l, the static contact angle reached the minimum. Then, the correlations of adhesion tension β, adhesion work Wa, surface tension γ and contact angle θ were investigated. It was confirmed that there was a positive correlation between adhesion tension β and surface tension γ, adhesion work Wa and γ, also a negative correlation between β and contact angle θ, Wa and θ. When the concentration of alidamycin aqueous solution was 3.6364 g/l, the corresponding adhesion tension and adhesion work of pesticide droplets on crop leaf surfaces were obtained. At last, the dynamic contact angle of validamycin aqueous solution with different concentrations on crop leaf surfaces was measured. It proved that if pesticides were over diluted, the utilization efficiency of pesticides would be reduced a lot. It was of important significance for further research on wetting property of pesticide droplets on crop leaf surfaces which provided a basis for scientific pesticide applications. Introduction In China, pesticides which assist in reducing the incidence of pests and diseases are widely used in agricultural ptactices. The use of pesticides can reduce 15 40% loss of crops. However, during the process of spraying pesticides, only 20 30% of its deposit on plant leaves, far below the average 50% in developed countries. The level of retention of pesticide droplets on plant surfaces significantly affects the application efficiency of pesticides (Dong et al. 2015). In fact, the retention of pesticide droplets is closely related to the wetting ability of the pesticide on plant surfaces and the wettability of plant leaves. The special wettability of plant leaves provides a model for manufacturing functional surfaces (Liu et al. 2010, Koch et al. 2009). So the research on wettability of plant leaves is of great significance. In agricultural field, the wettability of plant leaves and the wetting ability of pesticides should be integrated into account. The correlation of the leaf surface features and wetness of leaves were studied by many researchers (Pandey et al. 2003, Yu et al. 2009, Kolyva et al. 2012, Koukos et al. 2015). The adjuvant has a significant influence on the wetting ability of pesticides. Gimenes et al. studied the effect of adjuvants on the dispersion of droplets applied on soybeans (Gimenes et al. 2013). Spanoghe et al. investigated the influence of agriculture adjuvants on spraying droplets spectra (Spanoghe et al. 2007). Moreover, the wetting ability is related to the surface characteristics of crop leaves (Xu et al. 2011, Wang et al. 2013) and surface tension of pesticide droplets (Knoche et al. 1992, Hollowayet et al. 2000, *Author for correspondence: . College of Food Science and Engineering, Jilin University, Changchun 130022, China.