Persistence of Spirotetramat Residues in/on Brinjal and Soil

Dissipation of spirotetramat and its metabolite spirotetramat-enol on brinjal fruits and soil was studied under field conditions following three applications @ 90 and 180 g a. i. ha⁻¹ during kharif 2014. The average initial deposits of spirotetramat in brinjal fruits were below determination level (< 0.05 μg g⁻¹) and 0.08 μg g⁻¹ at standard and double doses, respectively. The residues reached below determination limit on the 1^st day. Residues of spirotetramat-enol were below determination level at either dose of application initially. On the 1^st day the residues built up to 0.07 μg g⁻¹ at double dose which declined to below determination level on the 3^rd day. The concentrations of spirotetramat and its metabolite spirotetramat-enol were combined for calculation of spirotetramat residues. The half-life (T_1/2) of the spirotetramat on brinjal fruits was 1.71 days for the double dose. Soil samples collected on the 15^th day revealed residues below determination level of 0.05 μg g⁻¹ at either dose. Considering the 1.0 ppm maximum residue limit (MRL) of spirotetramat on brinjal (Codex), the residues were below MRL from the day of application itself.