Screening And Field Application Of Pelletizing Coating Agents For Preventing And Controlling Important Pests In Cruciferous Vegetables

This paper studied the safety of thiamethoxam,thiocyclam and chlorantraniliprole on the growth of Chinese cabbage seeds,and treated Chinese cabbage seedlings with different concentrations of three insecticides.The indoor control effect of Phyllotreta striolata and Plutella xylostella with different sensitivities was studied.By comparing the test results its showed that thiamethoxam,an insecticide with strong internal absorption,was safe for seed growth and had good control effect on the important pests of cruciferous vegetables,Phyllotreta striolata and Plutella xylostella.Thiamethoxam was selected to combine with the technology of seed pelleted coating to prepare the pelleted coated cabbage seeds which contained different doses of thiamethoxam.The field effect was verified through further field experiments,the content of thiamethoxam in various parts of cabbage and soil was determined,and the emergence rate of thiamethoxam pelleted coated seeds under different storage periods was studied.The main findings are as follows:1.The safety of three insecticides on the growth of Chinese cabbage seeds was tested through the indoor pharmaceutical safety test.The results showed that the test concentration of thiamethoxam and chlorantraniliprole did not affect the germination potential and germination rate of Chinese cabbage.When the concentration of thiocyclam is greater than or equal 160mg/L,it can inhibit the germination potential and germination rate of Chinese cabbage.Thiocyclam had an great impact on the height of cabbage,followed by thiamethoxam and chlorantraniliprole.The rank of the safety of three different insecicides on Chinese cabbage is: chlorantraniliprole>thiamethoxam>thiocyclam.2.The results of indoor seedling toxicity test of Phyllotreta striolata and Plutella xylostella showed that,comparing to the thiocyclam,7d and 14 d seedlings treated with different concentrations of thiamethoxam had the best control effect and seedling-preserving effect on Phyllotreta striolata of Huizhou and Guangzhou,and the chlorantraniliprole is ineffective.the effect of 7d seedlings is better than that of 14 d seedlings,and the effect on Huizhou Phyllotreta striolata is better than that of Guangzhou.The bioassay of susceptible and field Plutella xylostella under 7 days of treatment with three insecicides at different concentrations,chlorantraniliprole had better control effect and seedling-preserving effect on susceptible Plutella xylostella,thiamethoxam had better control effect and seedlingpreserving effect on field Plutella xylostella.while the effect of thiocyclam is not good.3.Field trials of different doses of thiamethoxam pelletized coated cabbage seeds showed that 10g/kg,30g/kg and 60g/kg three treatments could reduce the rate of damaged plants of cabbage during its early growth,and different treatment there was no significant difference in the number of Phyllotreta striolata and the rate of insect strains.Among three treatments,treatment of 60g/kg affected the emergence rate of cabbage seeds in the field(the emergence rate was 78%),and treatment of 30g/kg had best seedling preservation effect(80.8%)in the early growth of cabbage and effectively protect the cabbage seedlings from the damage of Phyllotreta striolata armor.4.After different pelletized coating treatments,the field determination results of thiamethoxam showed that the content of thiamethoxam in the soil was the highest at1.37mg/kg,and the maximum content of thiamethoxam in the leaves is 2.65mg/kg,the highest in the stem is 1.79mg/kg,the highest in the root is 1.04mg/kg,the content of thiamethoxam measured in the field are all in the maximum residue limit of thiamethoxam(in Cruciferous vegetables)prescribed by the national standard(5mg/kg).The half-lives of thiamethoxam in the roots,stems and leaves of Chinese cabbage with the treatments of10g/kg,30g/kg and 60g/kg were 1.44 ～ 2.04 d,and the half-life of thiamethoxam in the soil was 3.32 ～ 3.69 d.5.The results of the determination of the emergence rate of Chinese cabbage seeds in different storage periods showed that,treated with three different dosages of thiamethoxam pelleted coated Chinese cabbage seeds,under different storage periods(the coated seeds had a storage time of 3,6,9 months),the emergence rate of 10g/kg pelleted coated seeds was89.33%,87%,83%;the emergence rate of 30g/kg pelleted coated seeds was 89.67%,83%,80%;the emergence rate of 60g/kg pelleted coated seeds was 80%,75%,73%;The emergence rate of naked seeds was 95.33%,73%,64%.The difference in the emergence rate of the same pelleted coating treatment seeds in different storage periods is not much different,and the emergence rate of naked seeds continues to decrease with the extension of storage time.