Behavior of oxydemeton-methyl in/on citrus fruits and soil in the hilly zone of Karnataka, India

Experiments were conducted to study the residue persistence and dissipation kinetics of oxydemeton-methyl (ODM) in/on citrus fruits following at the standard (0.025) and double dose (0.05%). The methodology included extraction with acetone, partitioning into chloroform, oxidation with 0.1 N potassium permanganate and partitioning into chloroform. The ODM sulfone residues were analyzed by gas liquid chromatograph (GLC). The initial deposit residues of oxydemeton methyl on citrus peel was 1.23 and 2.66 mg/kg from treatment at the standard and double doses, respectively. The residues persisted for 15 and 20 days and dissipated with the half-life of 2.2 and 4 days. Residue levels in citrus pulp reached highest of 0.018 and 0.057 mg/kg from standard and double treatments, which reached below detectable level after 20 days. The preharvest interval (PHI) of ODM on citrus was worked out to be 14 and 26 days for treatment at standard and double doses, respectively. The residues of ODM were below the detectable limit of 0.01 mg/kg in soil and citrus fruit at harvest.