Zhang Pengjiu, Wang Kaile, He Lifei, Fan Renjun, Liu Zhongfang, Yang Jing, Guo Ruifeng, Gao Yue
College of Plant Protection, Shanxi Agricultural University, Taiyuan, Shanxi 030031, People's Republic of China.
ACS Omega. 2023 Jun 6;8(24):22121-22131. doi: 10.1021/acsomega.3c02317. eCollection 2023 Jun 20.
Fruit tree leaves have different chemical compositions and diverse wax layer structures that result in different patterns of wetting and pesticide solution spreading on their surface. Fruit development is a time when pests and diseases occur, during which a large number of pesticides are needed. The wetting and diffusion properties of pesticide droplets on fruit tree leaves were relatively poor. To solve this problem, the wetting characteristics of leaf surfaces with different surfactants were studied. The contact angle, surface tension, adhesive tension, adhesion work, and solid-liquid interfacial tension of five surfactant solution droplets on jujube leaf surfaces during fruit growth were studied by the sessile drop method. CE and Triton X-100 have the best wetting effects. Two surfactants were added to a 3% beta-cyfluthrin emulsion in water, and field efficacy tests were carried out on peach fruit moths in a jujube orchard at different dilutions. The control effect is as high as 90%. During the initial stage when the concentration is low, due to the surface roughness of the leaves, the surfactant molecules adsorbed at the gas-liquid and solid-liquid interfaces reach an equilibrium, and the contact angle on the leaf surface changes slightly. With increasing surfactant concentration, the pinning effect in the spatial structure on the leaf surface is overcome by liquid droplets, thereby significantly decreasing the contact angle. When the concentration is further increased, the surfactant molecules form a saturated adsorption layer on the leaf surface. Due to the existence of a precursor water film in the droplets, surfactant molecules on the interface continuously move to the water film on the surface of jujube tree leaves, thus causing interactions between the droplets and the leaves. The conclusion of this study provides theoretical guidance for the wettability and adhesion of pesticides on jujube leaves, so as to achieve the purpose of reducing pesticide use and improving pesticide efficacy.
果树叶片具有不同的化学成分和多样的蜡质层结构，这导致农药溶液在其表面的湿润和铺展方式各异。果实发育阶段是病虫害高发期，此时需要大量使用农药。农药液滴在果树叶片上的湿润和扩散性能相对较差。为解决这一问题，研究了不同表面活性剂对叶片表面的湿润特性。采用静滴法研究了果实生长期间五种表面活性剂溶液液滴在枣树叶表面的接触角、表面张力、粘附张力、粘附功和固液界面张力。CE和吐温X-100的湿润效果最佳。将两种表面活性剂添加到3%的高效氯氟氰菊酯水乳剂中，在枣园对桃小食心虫进行了不同稀释倍数的田间药效试验。防治效果高达90%。在浓度较低的初始阶段，由于叶片表面粗糙度的影响，吸附在气液和固液界面的表面活性剂分子达到平衡，叶片表面的接触角变化较小。随着表面活性剂浓度的增加，液滴克服了叶片表面空间结构中的钉扎效应，从而使接触角显著减小。当浓度进一步增加时，表面活性剂分子在叶片表面形成饱和吸附层。由于液滴中存在前驱水膜，界面上的表面活性剂分子不断向枣树叶片表面的水膜移动，从而导致液滴与叶片之间产生相互作用。本研究结论为农药在枣树叶上的润湿性和粘附性提供了理论指导，以达到减少农药用量、提高农药药效的目的。
