Dissipation Studies of β-cyfluthrin and Imidacloprid as Combination Product in Brinjal (Solanum melongena L.)

With a view to study the dissipation of individual insecticide of an effective combination product β-cyfluthrin (9%) and imidacloprid (21%) in brinjal, field experiment was conducted during Rabi 2007–08. The product was applied as foliar spray thrice at weekly interval during flowering stage @ 18 + 42 g a.i. ha⁻¹ and 36+84 g a.i. ha⁻¹. Immediately afterapplication β-cyfluthrin in brinjal fruit was detected below its limit of quantitation (LOQ) at the standard dose. However, at higher dose the initial deposit of 0.037 μg g⁻¹ reached below LOQ on the third day. The corresponding levels for imidacloprid in brinjal fruits one hour after application were 0.035 and 0.062 μg g⁻¹ respectively, which reached below its LOQ on the 5^th and 10^th day. The half-life (DT₅₀) of imidacloprid in brinjal fruits was 1.67 and 3.82 days at standard and higher dose. Nonetheless, the half-life value of 1.83 days for β-cyfluthrin was obtained only at higher dose. The content of β-cyfluthrin being only 30% of the active ingredient in the formulation coupled with its non-systemic nature could have resulted in low levels of its residues in brinjal fruits.