Effects of Four Spray Adjuvants on Wettability of 25%Thiameth-oxam WG on Cowpea Leaves
The study is to screen pesticide spray adjuvants suitable for cowpeas and to get a better wettability and spreading effect on the surface of crops.The structure of the adaxial and abaxial surface of cowpea leaves were observed by scanning electron microscope,the critical surface ten-sion(CST)and surface free energy of cowpea leaves were calculated.The surface tension,the static contact angle and dynamic contact angle of three different concentrations of 25%thiamethoxam WG with four spray adjuvants were measured.The results showed that the surface tension of di-luted solution of 25%thiamethoxam WG was higher than the critical surface tension of cowpea leaves.The surface tension of 1 250-fold dilution of 25%thiamethoxam WG with adjuvant 0.4%silwet stik and 0.5%Maifei on cowpea leaf was 24.58 mN/m and 31.07 mN/m,respectively,while the CST of cowpea leaf was 32.31 mN/m.When adjuvant 0.5%Maifei was applied to 1 250-fold di-lution of 25%thiamethoxam WG,the dynamic contact angle declined faster than other three adju-vants,and the contact angle turned to 39.68° after 60 s.Better performance could be achieved when 25%thiamethoxam WG's 1 250-fold dilution with 0.5%adjuvant Maifei was applied to cow-pea leaves.
国家科技期刊平台
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