Security Analysis of Residual Deltamethrin in Tea Plantation

To investigate the final residues and dynamic degradation of deltamethrin sprayed on Fuyun 6,Jinguanyin,Tieguanyin and Shuixian(Camellia sinensis),a security analysis of residual deltamethrin in different tea plantation(Fu′an,Anxi and Wuyishan)was carried out after 500-3 000 times of 2.5% deltamethrin was air-dried or 1,3,5,7,10,15 days after spraying.The results showed that the reduce residues has a linear relation with diluted times of the pesticides.On the one hand,the residual amounts treated with the same concentrations were higher in spring tea than those of summer tea or autumn tea,and more residual contents would be found in green tea varieties(Fuyun 6) than those of oolong tea varieties(Jinguanyin).The half-life of the degradation was prolonged with the increased concentrations but with no significant differences.On the other hand,oolong teas had a long half-life of the degradation than those of green teas at the same concentrations,which respectively reached a significant level in spring.And there were significant difference of half-life among oolong tea varieties in every season sprayed with the same concentration of pesticides in each region.The usages of 500-3 000 times of 2.5% deltamethrin in the tea garden were relative safety concentrations.The status quo requirement of 5 days as the safety interval was appropriate according to the proposal of GB/T 8321.1-2000,Guideline for safety application of pesticides(Ⅰ),but 7days was recommended for non-polluted tea garden and export base to the European Union member countries.