The Residual Characteristic of Chromafenozide and Pyridalyl in Kale

BACKGROUND: It is a very important task to block dis-tribution of the agricultural products contaminated with pesticides in advance to protect consumers from residual pesticides among the agricultural products. Therefore, this study was performed to determine residual characteristics of pesticides in time-dependent manner and present scientific evidences for pre-harvest residue limit (PHRL) setting. METHODS AND RESULTS: The tested pesticides, chromafenozide and pyridalyl were sprayed onto the kale twice (seven day intervals) and then the plant samples were collected at 0 (after 3 hours), 1, 2, 3, 5, 7, and 10 days after the last spraying. Residual concentration of chromafenozide in kale decreased with 74.9% (of decreased frac-tion, field 1) and 85.3% (field 2) and pyridalyl decreased with 81.2% (field 1) and 85.8% (field 2), calculated by comparisons of the concentrations at 0 day and 10 days. Also biological half-lives of chromafenozide in kale were 5.6 day (field 1) and 3.4 day (field 2), and those of pyridalyl were 4.3 day (field 1) and 3.5 day (field 2). CONCLUSION(S): If the residues of chromafenozide and pyridalyl in kale from 10 days before harvest are less than 37.6 mg/kg and 58.9 mg/kg, respectively, it is expected that safe kale below MRL can be supplied on the pre-harvest day.