Pesticide residues in the spring cabbage (Brassica oleracea L. var. capitata) grown in open field

A method was established to evaluate multi-residual dynamics of the pesticides (chlorpyrifos, dimethoate, cyhalothrin, cypermethrin, fenvalerate, deltamethrin and chlorothalonil) in the spring cabbage, Brassica oleracea L. var. capitata. The results showed that the pesticide residues were closely related with the times and dosage of application, and the weather after spraying. The half-lives of the seven pesticides in the vegetable were 2.0, 1.6, 1.6, 2.3, 2.2, 1.5 and 1.8 days, respectively. If the cabbages were treated one time at normal dosage of pesticides, and all pesticides maximum residue limits (MRLs) were not exceeded according to the recommended pre-harvest interval. However, if the vegetables were treated four times at the maximal dosage with a five-day’s interval, the half-lifes of chlorpyrifos, cypermethrin and chlorothalonil in the vegetable were 2.9, 2.6 and 4.1 days, respectively, and the final residual amount of chlorothalonil exceeded its MRL on cabbage, but the final residual amounts of cypermethrin and chlorpyrifos were below its MRLs on the cabbage. Furthermore, in both one-time and four-time spraying treatments, the final degradation rates of pesticides residues were above 80%.