Residues of Diazinon in Growing Chinese cabbage: A study Under Greenhouse Conditions

Chinese cabbage, Braccica campestris has long been consumed as a staple food for Koreans in various forms of fresh, salted, and fermented Kimchi. Cultivation of the crop under greenhouse has become a general practices to fulfill its off-seasonal consumer`s demand. However, agricultural practices of the crop have always accompanied with heavy applications of pesticides caused by severe outbreaks of diseases and pests under warm and humid circumferences. Since dissipation patterns of pesticide residues in/on the crop under greenhouse conditions are quite different from those in the open-air, changes of diazinon, O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphorothioate, in/on the Chinese cabbage applied by foliar spraying under greenhouse were studied. Diazinon 34% EC was applied with dilution of recommended and double dose to the crop. The shoots of crop were harvested immediately after this application and at regular intervals over a 10-day. After sample preparations, the diazinon residue was analyzed using gas chromatography equipped with electron capture detector (GC/ECD). Initially deposited amounts of the chemical in/on the crop right after applications with recommended and double doses were 8.3 and 15.2 ㎎/㎏, respectively. The residue levels after 10 days of application were 0.03 and 0.09 ㎎/㎏ with 1.3 and 1.5 days of half-life in/on the crop, respectively. In consequent, 10 days of pre-harvest interval (PHI) for diazinon EC formulation in/on Chinese cabbage under greenhouse condition was fulfill maximum residue level set by Korea Food and Drug Administration (KFDA, 0.1 ㎎/㎏).