Studies on Dissipation Pattern of Tolfenpyrad and Harvest Time Residues in Cabbage under Field Conditions

Abstract

The use of Tolfenpyrad, a broad-spectrum insecticide in preventing the crop losses, studies on its dissipation pattern and safe waiting period required were studied. Tolfenpyrad 15 EC @ 150 g a.i. ha-1 at recommended dose under field conditions to assess the differences in rate of dissipation, and also to recommend safe waiting periods and half-life period based on MRLs established by FSSAI. Tolfenpyrad was sprayed two times at head formation stage and cabbage samples collected at regular intervals were analysed for residues. The dissipation pattern of tolfenpyrad 15 EC was studied collecting samples at regular intervals i.e, 0, 1, 3, 5, 7, 10,15 and 20 days after last spray and analyzed. The initial deposits of 0.184 mg kg-1 tolfenpyrad recorded at 2 hours after last spray dissipated to 0.145, 0.086, 0.021, 0.010 mg kg-1 with dissipation percent of 21.19, 53.26, 88.58 and 94.56 at 1,3,5,7 days after final spray. The tolfenpyrad residues dissipated to less than LOQ (<LOQ) of 0.01 mg kg-1 after 10 days showing a hundred per cent dissipation. The safe waiting period and half-life for tolfenpyrad were 7.09 and 1.590 days, respectively. The residues of tolfenpyrad in cabbage and soil samples were less than LOQ both field conditions at harvest (20 days after last spray).