Dissipation kinetics of fenazaquin residues in okra and soil under subtropical conditions of Punjab, India

The supervised field trials were conducted to estimate the dissipation pattern of fenazaquin residues on okra and soil following its three applications @ 25, 50 and 125 g a.i. ha(-1.) The residue analysis was carried out using high-performance liquid chromatography followed by confirmation with liquid chromatography-mass spectrometry. The average initial deposits were estimated to be 1.663, 2.037, 3.117 and 1.611, 2.299, 3.100 mg kg(-1) on okra crop during the year 2017-18 and 2018-19, respectively, at three application rates, i.e.25, 50 and 125 g a.i ha(-1).The residues declined below the limit of quantification (LOQ) (<0.01 mg kg(-1)) after 10 days during 2017-18 and on 15th day during 2018-19, following its application @ 25 g a.i. ha(-1). However, with the application @ 50 and 125 g a.i. ha(-1), the residues were below LOQ on 15th day of sampling during both the years. Considering the LOQ <0.01 mg kg(-1), the pre-harvest interval of 15 days is suggested for the safe consumption of okra fruits following its application @ 25 g a.i. ha(-1). The residues dissipated with half-life of 1.31, 1.59, 1.86 and 1.62, 1.75, 1.92 days at the three application rates during both the years. None of the residues were found in soil samples collected after 15 days of the last application.