Residue and dissipation dynamics of difenoconazole in bagged and non-bagged apples

In order to compare the residue of difenoconazole in bagged and non-baggged apples,gas chromatography-electron capture detector(GC-ECD) was used to analyze the dissipation dynamic of difenoconazole in apples under field condition.The results showed that in 2011 and 2012,the half-life of difenoconazole was 12.8 d and 15.5 d with the original deposition of 0.44 and 0.17 mg/kg in non-bagged fruits,respectively,while the half-life was 31.9 d in bagged fruits in 2012 with the original deposition of 0.056 mg/kg in fruits.The two years' experments showed that spraying 2-3 times of difenoconazole in recommended concentration of 66.7 mg/L and 1.5 times concentration 100 mg/L respectively from 35 to 42 days before harvesting,the residues of difenoconazole at 7 d after the last spray in bagged and non-bagged apples were all lower than China's maximum residue limit 0.5 mg/kg.The residual in bagged apples was lower than 0.03 mg/kg.It indicated that the recommendation dosage of difenoconazole was safe and bagged apple is a better manner for safe apple production.