Present situation of pesticide residues and biological suppression of pests and diseases in Chinese tea gardens

Abstract

Several insecticides, germicides and herbicides which, are now prohibited, are still used in Chinese common tea gardens. Applied amounts of the pesticides with high toxicity and long time residues, such as methomyl, cannot bypass certain limits in A-grade green food tea gardens. Pesticides are forbidden to be used in AA-grade green food tea gardens and organic tea gardens. Pesticide residues in a large number of merchant teas exceeded the national standard during 1998 - 2001. According to national standard, the number of samples exceeding standard percentage of 4200 output tea samples (including green tea, black tea, scented tea and oolong tea) in 2001 reached 6.55 %. However; the exceeding standard percentage was 0.4 % for 228 output tea samples in 2002. Safety time internal, half-life and MRL values of main pesticides used in Chinese tea gardens have been now introduced. The application of natural enemy insects, spiders and pathogenic microorganisms in biological control has also been summarized. 119 Species of main natural enemy insects have been recorded. The joint application of insect semiochemicals and pathogenic microbes, the approach to chemical mechanism of tea plant resistance to pests and disease causing organisms by physiological and biochemical techniques, and tea breeding against pests and diseases by molecular biological techniques will be the key research fields of biocontrol of tea pests and diseases in China in the near future.