Dissipation Kinetics, Residue Status and Risk Assessment of Trifloxystrobin and Tebuconazole Combi-product in Cowpea

The dissipation and residues of trifloxystrobin and tebuconazole @ 87.5+175 and 175+350 g a.i. ha⁻¹ are reported on cowpea under field condition. After two foliar sprays at 10-day interval, cowpea pods were collected at 0 (1 h), 1, 3, 5, 7, 10, 15, 20 and 42 days (harvest). The initial deposits of trifloxystrobin were 2.27 and 4.72 mg kg⁻¹, whereas that of tebuconazole were 6.51 and 12.60 mg kg⁻¹ at the standard and double doses, respectively. The dissipation of trifloxystrobin and tebuconazole fitted well to first-order kinetics with half-life values ranging between 1.70–1.72 and 2.29–2.41 days at standard and double doses, respectively. Maximum residue limits (MRLs) being not available for both the fungicides, considering LOQ (0.05 mg kg⁻¹) as MRL, a PHI of 20 days is proposed for cowpea pod (green) and 42 days for seeds. Theoretical maximum dietary intakes (TMDI) were well below maximum permissible intake (MPI) in cowpea pods. The acute and chronic hazard was also less than 0.4 and 5 per cent. Thus, the application of trifloxystrobin and tebuconazole as combi-product at the standard as well as double doses on cowpea did not impart any human health risk at the recommended PHI.