Dissipation Kinetics of Novaluron-Indoxacarb Combi-product in Soil under Tomato Crop (Lycopersicon esculentum Mill.)

Dissipation of novaluron-indoxacarb combi-product sprayed @ 43.31 + 37.13 g a. i. ha⁻¹ (normal dose) and 86.62 + 74.26 g a. i. ha⁻¹ (double the normal dose) at 50 per cent fruiting stage on tomato crop (Lycopersicon esculentum Mill.) is reported in sandy loam soil under the crop. Soil samples collected periodically at 0 (1h after application), 1, 3, 5, 7, 10 and 15 d after application and eluted with 125 mL of hexane: acetone (9: 1, v/v) in plexi glass column (90 cm × 22 mm i.d.) and finally made upto 2 mL in hexane were estimated using GC-ECD system equipped with capillary column. Average recoveries of novaluron and indoxacarb in soil fortified at 0.01, 0.05 and 0.10 mg kg⁻¹ ranged from 91.10 to 94.00 per cent. LOD and LOQ were calculated as 0.005 and 0.01 mg kg⁻¹ for the two molecules respectively. The initial deposits of novaluron were 0.03 and 0.08 mg kg⁻¹ and that of indoxacarb 0.43 and 0.57 mg kg⁻¹ at the single and the double doses respectively. The dissipation of novaluron and indoxacarb followed first order kinetics with half-life ranging from 0.63 to 0.71 d in novaluron and 1.87 to 2.17 d in indoxacarb at the two doses.