有机硅助剂对氯虫苯甲酰胺防治稻纵卷叶螟的增效作用研究

为探索有机硅助剂Silwet408对杀虫剂药液理化性能的影响及药液雾滴在稻叶上的行为与对稻纵卷叶螟Cnaphalocrocis medinalis Guenée防效的内在关系,在室内条件下研究了在200 g/L氯虫苯甲酰胺悬浮剂稀释液中添加助剂Silwet408后表面张力、黏度、pH值以及在稻叶上最大持留量的变化,借助OCG法对叶片的表面特性进行表征,围绕叶片倾角分析了单个雾滴在稻叶上的黏附行为,并进行了田间药效试验。结果表明:水稻叶片正、反面表观表面自由能分别为31.48 mJ/m^2和34.19 mJ/m^2;倒二叶和倒三叶的叶角较小,分别为(11.09±2.74)°和(19.98±5.67)°,表明水稻为高倾角叶片形态,不利于雾滴在稻叶上的黏附。200 g/L氯虫苯甲酰胺悬浮剂4000倍和5000倍稀释液的表面张力分别为(44.64±1.04)mN/m和(46.14±0.62)mN/m,均大于稻叶的表观表面自由能,其药液的单个雾滴在79°和70°的倾角稻叶上均呈滚落状态;添加125 mg/L的Silwet408后,药液的表面张力小于稻叶的表观表面自由能,单个雾滴能够黏附在倾角稻叶上并润湿,同时药液在稻叶上的最大持留量也呈极显著增加;200 g/L氯虫苯甲酰胺悬浮剂5000倍稀释液的pH值和黏度在添加Silwet408前后变化不大。田间试验结果表明,添加125 mg/L的Silwet408后,200 g/L氯虫苯甲酰胺悬浮剂5000倍稀释液对稻纵卷叶螟药后14 d的保叶效果和杀虫效果均显著提高。综合研究结果表明,在200 g/L氯虫苯甲酰胺悬浮剂5000倍稀释液中添加125 mg/L的Silwet408可使喷雾药液与水稻植株特性相匹配,进而提高氯虫苯甲酰胺对稻纵卷叶螟的防治效果。

Study on the synergistic effect of organosilicon adjuvant on chlorantraniliprole in the control of rice leaffolder, Cnaphalocrocis medinalis Guenée

In this study, the effect of the trisiloxane surfactant (Silwet408) on the physicochemical properties of pesticide solutions, and the internal relation between the behavior of single droplets of Silwet408 solution on rice leaf surface and the control effect on rice leaffolder, Cnaphalocrocis medinalis Guenée were explored. The change of surface tension, viscosity, pH value and maximum retention of chlorantraniliprole 200 g/L suspension concentrate(SC) diluent solution were determined. The leaf surface was characterized by OCG method. And the adhesion behavior analysis of single droplets on rice leaves was conducted according to leaf inclination angle. Field efficacy tests were also carried out. The results showed that the apparent surface free energy (SFE) values of the adaxial and abaxial rice leaf surface were 31.48 mJ/m2 and 34.19 mJ/m2, respectively. The leaf angles of the second and third leaves were relatively small and their respective average values were (11.09 ± 2.74)° and (19.98 ± 5.67)°, respectively, which indicated that the leaf shape of high inclination angle was not conducive to the adhesion of droplets on the rice leaves. The surface tensions of chlorantraniliprole 200 g/L SC 4 000 times and 5 000 times diluent solution were (44.64 ± 1.04) mN/m and (46.14 ± 0.62) mN/m, respectively, which were higher than that of the rice leaf apparent surface free energy. Their single droplets of those solutions rolled off rice leaves with the inclination angles of 79° and 70°, respectively. After the addition of Silwet408 adjuvant at the concentration of 125 mg/L, the surface tension of the solution was lower than that of therice leaf apparent surface free energy. Its single droplet of the solution adhered to rice leaf with inclination angles and the leaf became wetted. The maximum retention amount of the solution on the rice leaf was also significantly increased. The pH and viscosity values of chlorantraniliprole 200 g/L SC diluent solution had a little change with or without Silwet408 adjuvant. Field experiments showed that the protecting effect of leaves and the insecticidal effect of chlorantraniliprole 200 g/L SC 5 000 times diluent solution on C. medinalis were significantly improved 14 days after spray by adding Silwet408 adjuvant at the concentration of 125 mg/L. In a word, physicochemical properties of the spray solution could match with the characteristics of the rice leaf after adding Silwet408 adjuvant at the concentration of 125 mg/L, which could improve the control effect of chlorantraniliprole 200 g/L SC 5 000 times diluent solution against rice leaffolder.