Surface tension and spreading coefficient of single-and mix-pesticide solutions with aerial spraying organosilicone adjuvant

Abstract

Abstract: Recently, unmanned aerial vehicles (UAVs) have been widely used to spray pesticides to control diseases and pests of many crops. During the process of pesticide application by UAV spraying, aerial spraying tank-mix adjuvants are usually mixed with pesticide solution to improve the efficiency of pesticides. Preventing pesticides depositing in off-target area is important in enhancing pesticide utilization. Improving the wetting and spreading of pesticides is one of the most important ways to reduce pesticide droplets running off from the target. This study is focusing on the effects of aerial spraying tank-mix organosilicone adjuvant (OA) on surface tension and spreading coefficient of pesticide solutions. Six pesticide solutions used alone and mixed together of different concentrations are prepared under field application conditions. Surface tension and spreading coefficient of the solution with and without OA were measured, respectively. The results show that OA could significantly lower surface tension and increase spreading coefficient of pesticide solutions regardless of solution concentrations. OA with concentration higher than critical micelle concentration (CMC) could not further decrease surface tension, but still could significantly increase spreading coefficient of the solution. For solutions with single pesticide belongs to different formulations, the minimum needed concentration of OA is different due to formulation type. The minimum concentration of OA for solution of suspension concentrate and aqueous solution (0.5‰-0.7‰) is lower than that of solutions of emulsifiable concentrate (EC) (2.0‰-5.0‰). For solutions of several pesticides mixed together, the minimum concentration of OA is related to the number of EC formulation in the solution. For pesticide solutions containing one EC formulation, the minimum concentration of OA is 2.0‰; for pesticide solutions containing two or three EC formulation, the minimum concentration of OA is recommended to be 5.0‰-10.0‰. These results suggest that the concentration of OA needed for pesticide solution should be evaluated before field application considering pesticide belonging to different formulations mixing together for application. Keywords: aerial spraying adjuvant, organosilicone, surface tension, spreading coefficient DOI: 10.33440/j.ijpaa.20210401.159 Citation: Meng Y H, Wang M M, Wang Z G, Hu H Y, Ma Y. Surface tension and spreading coefficient of single-and mix-pesticide solutions with aerial spraying organosilicone adjuvant. Int J Precis Agric Aviat, 2021; 4(1): 6–13.