Residual dissipation behavior of chlorpyrifos 480 EC in chrysanthemum flower and soil

The residue decline dynamics were investigated in field at two different application concentrations by spraying chlorpyrifos 480 EC in Chrysanthemum morifolium and soil.The impact of different temperature on chlorpyrifos decline in dry chrysanthemum bud was studied. The results showed that when sprayed at the concentration of 0.48 and 0.72 kg/hm2, the half-lives were 9.24-10.82 days in soil and 2.94-4.22 days in bud. There were significant differences between different temperatures in half-lives in dried chrysanthemums. When 0.48 kg/hm2 and 0.72 kg/hm2 chlorpyrifos were sprayed twice a season, the final residues of chlopyrifos at 21 days after last application in dry chrysanthemum bud were 0.58 and 0.89 mg/kg, which were below the national MRL of chlorpyrifos on tea (1 mg/kg).