Abstract
Objectives: A field trial was carried out in Kashmir valley to determine the persistence of fenazaquin 10EC (Magister) in Red Delicious variety of apple at recommended (0.004%) and double the recommended (0.008%) application rates.
Methods: The spray was conducted one month prior to harvest. The plants treated with simple tap water were treated as control. Samples were collected at 0, 3, 7, 10, 15, 20 days and harvest. The procedure followed for extraction and cleanup was that of Luke et al. (1985) modified by Sharma (2007) and the final analysis was carried out on a Varian 450 (Walnut Creek, CA, USA) gas chromatograph (GLC) equipped with Thermionic Specific detector (TSD).
Results: After computation of data, the initial deposit was recorded as 3.18 +/- 0.03 mu g g - 1 and 6.98 +/- 0. 08 mu g g - 1 at two concentrations, respectively. Fenazaquin (0.004%) dissipated to 96.91 per cent in 20 days after application and was not detectable beyond this period. Fenazaquin (0.008%) however, persisted upto 30 days recording 95.84 per cent dissipation at that time.
Conclusions: The progressive dissipation of fenazaquin (0.004%) and fenazaquin (0.008%) residues down to their tolerance limits suggested a waiting period of 18.55 and 30.49 days with a half-life period of 3.62 and 4.12 days, respectively. The terminal residue of fenazaquin at the lower rate was below maximum residue limit (MRL) set by European Union, however above MRL at the higher rate. (C) 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University.