Residue and decline dynamics of fluxaproxad and pyraclostrobin in mango under supervised field conditions

The residue behaviors of fluxaproxad and pyraclostrobin in mango were investigated. The residue and decline dynamics for field trials of fluxaproxad and pyraclostrobin were designed and conducted in Guangdong and Guangxi during the years of 2012 and 2013. An effective method was developed for the determination of the above two pesticides. The mango samples were extracted by acetone, followed by liquid-liquid-extraction with ethyl acetate and detected with HPLC-PDA (high performance liquid chromatography with photo-diode array). The dissipation and terminal residues of fluxaproxad and pyraclostrobin in mango samples were studied with the above analytical method. The results indicated that the half-lives of fluxaproxad and pyraclostrobin in mango were 7.2-9.1 and 8.0 -11.0 d, respectively. The mango trees were sprayed for 3 to 4 times with 10-15 days application interval using 42.4% SC at the dosage 200 and 300 mg/L at the young fruit period. The samples were collected at 7 to 14 days after the last spray. The terminal residues of those two pesticides were 0.004-0.053 mg/kg and 0.004-0.072 mg/kg determined by the above conditions. The residue of pyraclostrobin met the maximum residue limit (MRL, 0.05 mg/kg), according to the trial results. It is suggested that the MRL of fluxaproxad in mango in China should be set as 0.2 mg/kg.