喷雾助剂对氟啶虫胺腈在富士苹果叶片表面润湿和持留的影响

为明确喷雾助剂在苹果园化学防治中的作用,采用表面张力、接触角和最大稳定持留量等分析了GY-T12、NF-100和迈润等3种喷雾助剂在达到临界胶束浓度 (CMC) 时对22%氟啶虫胺腈悬浮剂药液的表面张力及其在苹果叶片表面润湿性能和持留量的影响。结果显示:当添加的3种喷雾助剂达到其CMC时,氟啶虫胺腈药液表面张力降低至27.64~35.64 mN/m;根据水滴在苹果叶片表面的接触角小于或大于90°判定苹果叶片近轴面为亲水性表面、远轴面为疏水性表面,添加助剂使药液在近轴面和远轴面30 s的静态接触角分别降低23.2°~41.3°和68.0°~93.5°,同时使亲水性近轴面黏附功降低5.36~12.56 mJ/m2,而黏附张力增大9.27~11.26 mN/m,在疏水性远轴面黏附功与黏附张力分别增大27.45~36.66 mJ/m2和47.55~53.28 mN/m,对改善远轴面的黏附润湿性更显著;药液表面张力和最大稳定持留量存在抛物线状函数关系,当表面张力为40.89 mN/m时,持留量达最大值12.53 mg/cm2;3种助剂中,NF-100和GY- T12可显著增加药液持留量,且GY-T12对靶标害虫苹果黄蚜有显著增效作用。本研究结果表明,在苹果园应用时应依据预期目标选择适当的喷雾助剂,并通过调节药液表面张力使其处于适宜范围以增加药液持留量、提高对靶标害虫的毒力。

The influence on wettability,retention of sulfoxaflor at Fuji apple leaves surface by adding spray adjuvants

In order to clarify the important role of spray adjuvants in the chemical control of apple orchard, the effects of three spray adjuvants GY-T12, NF-100 and Mairun on the physicochemical properties, wettability and retention of sulfoxaflor 22% SC were evaluated at CMC by measuring the surface tension, the contact angle and the maximum retention, and the synergistic effects to Aphis citricola were investigated. The results showed that the addition of three spray adjuvants reduce the surface tension of solutions from 50.65 mN/m to 27.64-35.64 mN/m. According to the contact angle of water droplets on the surface of apple leaves, less or greater than 90°, the adaxial surface is judged as a hydrophilic surface and the abaxial surface was judged as a hydrophobic surface. The addition of adjuvants decreases 30 seconds static contact angles on the adaxial surface by 23.2°-41.3° and by 68.0°-93.5° on the abaxial surface. The wettability assay showed when the concentrations of three spray adjuvants reached CMC, the adhesion work decreased by 5.36-12.56 mJ/m2 while the adhesion tension increased by 9.27-11.26 mN/m between the droplets and the adaxial surface, the adhesion work and adhesion tension increased by 27.45-36.66 mJ/m2 and 47.55-53.28 mN/m between the droplets and the abaxial surface. Then, the regression equation between the maximum retention and surface tension was established, it showed that the maximum retention is 12.53 mg/cm2 when the surface tension is 40.89 mN/m. Among the three spray adjuvants, NF-100 and GY-T12 significantly increase the retention of pesticides, moreover, the synergistic effect of GY-T12 on A. citricola is notable. Therefore, the selection of spray adjuvants in apple orchards should macth the expected goals, and the proper adjuvant is feasible to regulate the surface tension of pesticide in an appropriate range to increase the retention and improve the toxicity to target pests.