The Effect of Fruit Harvest Time and Refrigeration on Reducing Pyridaben Acaricide Residues in Strawberry Fruits

Effect of refrigeration and different harvesting times were investigated to remove residue of pyridaben from strawberry.  Transplants of Strawberry were grown in greenhouse and fruit samples were taken at 1, 4, 24, 48 and 72 hours and 7, 14 and 21 days after spraying of pyridaben (Sanmite® 20% WP) at the recommended and twice the recommended doses (0.4 and 0.8lit ha-1 respectively). For cooling treatment, fruit samples were refrigerated for 48 hours at 4°C. The study was done as factorial experiment in a completely randomized design (pyridaben doses and harvesting times after spraying) with three replications. Gas chromatography-electron capture detector (GC-ECD) method was used to determine pyridaben residues in strawberry fruits. The recovery rate of acaricide was 98-105% in this method and detection limit of machine was 50µg kg-1. The results revealed that the maximum residual concentrations of pyridaben acaricide in strawberry fruits were observed with an average of 0.42 mg kg-1 for the recommended dose and 0.71mg kg-1 for twice the recommended dose at 4 and 24 h after application, respectively, which in twice the recommended dose was higher than the MRL (5mg kg-1). Storing fruits in refrigerator for 48 hours had little effect on reducing pyridaben residues in them, and at twice the recommended dose, the concentration of pesticide in fruits was higher than that of Codex standard level.