Persistence behavior of combination mix crop protection agents in/on eggplant fruits

Persistence behavior of two combination mix formulations of insecticides viz. profenofos + cypermethrin (Roket 44EC) and chlorpyrifos + cypermethrin (Nacraj-505) were studied in eggplant fruits following spray application at recommended and double dose. Half-life values were calculated from first order dissipation kinetics, in case of Roket 44EC, residues of cypermethrin on fruits dissipated with half-life of 2.15-2.31 days, whereas residues of profenofos dissipated with the half-life of 0.91-1.86 days. Profenofos residues persisted beyond 7 days in soil, whereas residues of cypermethrin were below detection limit on 0-day itself. Dissipation of chlorpyrifos residues in the combination mix with cypermethrin (Nacraj-505) followed first order kinetics with the half-life values of 3.27-3.10 days. In soil, chlorpyrifos residues were below detectable limit even on 0-day at recommended dose of application. More than 90% dissipation was recorded on 7 day, although residues persisted beyond 15 days at double the recommended dose. Half life of dissipation for cypermethrin calculated from first order dissipation kinetics varied from 2.19 to 3.27 days. In soil, no residues of cypermethrin were detected even on 0-day at recommended dose.