Washing fresh tea leaves before picking decreases pesticide residues in tea

Abstract

BACKGROUND The use of pesticides during tea plant cultivation helps agricultural production and prevents and controls pests, diseases and weeds. It is of the utmost importance to balance pesticide application with tea quality, safety and consumer health. The uptake of pesticides into plants may lead to the presence of residues that are hazardous to human health, especially for some foliar‐applied insecticides. The movability or penetration behavior of a pesticide remains unknown after it has been sprayed on a tea leaf. RESULTS Two organophosphate (acephate, trichlorfon) and three neonicotinoid pesticides (imidacloprid, thiamethoxam and acetamiprid) were confirmed with respect to their removal from the treated fresh leaves of tea saplings via washing in a phytotron. Four of the targets have little penetrative ability into tea leaves, mainly existing (> 92%) on the tea leaf surface, except for trichlorfon (> 70%), for 30 days. With higher vapor pressures, trichlorfon and acetamiprid had relatively higher penetration ratios of 8.63–29.60% and 0.28–8.03% respectively. Two organophosphate insecticides were found to degrade more quickly, with lower final amounts of residues on and in the whole leaf compared to the neonicotinoid pesticides. In a field test, these residues could be reduced by 45–72% after a pre‐harvest interval of 3 days, and by 16–89% after 7 days, when the fresh tea shoots were sprayed with 2 or 4 L m−2 water. CONCLUSION Pesticides with different structures have different penetration abilities on the tea leaf surface, and some pesticides in commercial tea can be reduced by spraying with water before fresh leaves are picked. © 2020 Society of Chemical Industry

Quantitative Study on Anti-Pest Activity of Natural Products Based on Visualization Framework of Knowledge Graph

“…Owing to the pivotal role of natural alkaloid products in the management of pests, many scholars have conducted in-depth research on them [78][79][80][81] . Xia et al [82] , for the first time, studied the antifeedant effects of hexahydro-benzophenanthridine alkaloids on mosquito larvae and other pests.…”

Orthogonal optimization for effective classification of different tea leaves by a novel pressure stabilized inclined chamber classifier

“…Therefore, mechanical picking becomes an inevitable trend (Yu et al, 2020). Tea pickers can not only improve work efficiency and increase benefits, but also save a large number of laborers, relieve the picking peak period (Yang et al, 2021), shorten the picking cycle, and can be a key measure to ensure the quality of fresh leaves, which is conducive to the scale and mechanization of tea production (Gao et al, 2020). However, mechanical picking cannot classify fresh leaves, and the picking method is not perfect, which may damage the tea leaves as well as affect the growth of the tea tree.…”

“…Tea pickers can not only improve work efficiency and increase benefits, but also save a large number of laborers, relieve the picking peak period (Yang et al, 2021), shorten the picking cycle, and can be a key measure to ensure the quality of fresh leaves, which is conducive to the scale and mechanization of tea production (Gao et al, 2020).…”