摘要
OBJECTIVES:A field experiment was conducted at Agricultural Research Station for irrigated crops at Thasara,Anand Agricultural University,Anand,to study the dissipation and risk assessment ofβ-cyfluthrin and imidacloprid as combination product in/on chickpea.MATERIALS AND METHODS:Solomon 300 OD comprising 9 per centβ-cyfluthrin and 21 per cent imidacloprid was foliar sprayed at the doses of 18+42g a.i.ha−1(standard dose)and 36+84g a.i.ha−1(double dose).Totally three sprays were made at an interval of 1 week starting from fruiting stage.RESULTS AND DISCUSSIONS:The residues ofβ-cyfluthrin estimated using gas chromatograph with electron capture detector(GC-ECD)showed an initial deposit of 0.16 and 0.27μg g−1 in standard and double doses,respectively.The residues for corresponding doses persisted till 7th and 10th day after application and reached below determination level of 0.01μg g−1 on the 10th and 15th day,respectively.Imidacloprid was estimated using high performance liquid chromatography(HPLC)and showed initial deposits of 1.22 and 2.7μg g−1 in standard and double doses,respectively.Its levels reached below the determination level(0.01μg g−1)on the 15th day in green pods.Statistical analysis of dissipation kinetics showed thatβ-cyfluthrin followed zero-order kinetics in standard dose with half-life of 7.27 days.In double dose,the dissipation kinetics followed first-order kinetics with half-life of 9 days.Imidacloprid followed first-order kinetics in both the doses with half-life of 6.7 and 7.7 days.CONCLUSIONS:A pre-harvest interval(PHI)of 15 days is suggested.Theoretical risk assessment calculated as hazard quotient was less than 1,rendering the use of combination product as safe-provided proper PHI is followed.
