Uptake and Translocation of Ethoprophos Mixed with Soil for Cultivation of Preceding Crop into Succeeding Crop

BACKGROUND: Unintentional residual pesticide in soil derived from preceding crops and the transfer to succeeding crops was considered a critical barrier for positive list system (PLS).Thus, an uncertain risk is predicted for ethoprophos applied at cultivation of preceding crop (Korean cabbage) to succeeding crop (spinach).METHODS AND RESULTS: Ethoprophos was treated on soil following the recommended dose and 5 times dose according to the safe use guidelines for Korean cabbage after seeding.On the 4 days after harvesting of preceding crop, spinach was sowed.The initial residual amounts of ethoprophos on soil (7.081-19.493mg/kg) were decreased to 3.832-7.218mg/kg until the harvest of Korean cabbage, and then finally decreased to 0.011-0.079mg/kg after spinach cultivation.The uptake rates of ethoprophos from soil by Korean cabbage were 0.01-0.03%and distributed to root (0.150-0.903 mg/kg) and shoot (0.021-0.151 mg/kg), respectively.The residual amounts of uptake and trans-location from preceding crop cultivated soil to spinach edible part were found to be below LOQ. CONCLUSION:The plant back internal (PBI) for ethoprophos is not recommended during sequential cultivation of leafy vegetables, since the residual amounts of ethoprophos in spinach were less than MRL (0.02 mg/kg).