Residues and dissipation of chlorothalonil and azoxystrobin in cabbage under field conditions

Chlorothalonil and azoxystrobin, as efficient and broad-spectrum fungicides, are two widely used fungicides to control downy mildew and anthracnose on cabbage. For the safe and rational use of these two pesticides on cabbage, their residues and dissipation were studied under field conditions. The trial results showed that chlorothalonil and azoxystrobin residues were affected by the frequency and dosage of application, and the weather condition post-application. Chlorothalonil and azoxystrobin dissipated rapidly in cabbage with the mean half-live of 1.7 and 0.4days at three geographical experimental plots in China, respectively. The terminal residues of chlorothalonil and azoxystrobin in cabbage at harvest time were all below the maximum residue limit (MRL, 6mgkg(-1) for chlorothalonil and 5mgkg(-1) for azoxystrobin) established by Codex Alimentarius Commission. It suggested that this formulation of chlorothalonil and azoxystrobin (560gL(-1), SC) may be safer under the recommended dosage. Given that in China no MRL has been set for chlorothalonil and azoxystrobin in cabbage, this study could provide a guidance for establishing MRL, and the safe and rational use of these two pesticides.