Residues of Trifloxystrobin and Tebuconazole in/on Tomato (Lycopersicon esculantum Mill.) and Soil

A supervised field trial was conducted on tomato at College of Agriculture, Vellayani, Thiruvananthapuram, Kerala during 2011 to study the residues of a combination product Nativo 75 WG (trifloxystrobin 25% + tebuconazole 50%) when applied at 87.5 + 175 and 175 + 350 g a.i. ha^−1. The combination product was applied thrice at 7 days interval starting from fruit setting stage. Residues of trifloxystrobin along with its metabolite and tebuconazole were estimated using Gas Chromatograph – Mass Spectrometer. Tomato fruits analysed after the third application revealed initial deposits of trifloxystrobin of 1.21 and 3.08 μg g⁻¹ at standard and higher doses, respectively, which reached below determination limit of 0.05 μg g⁻¹ on the 25^th and 30^th day with corresponding half life of 4.78 and 5.10 days. Residues of trifloxystrobin metabolite CGA 321113 were not detected. Risk assessment of the fungicides was carried out and is reported. Tebuconazole showed initial deposits of 2.61 and 8.74 μg g⁻¹ for standard and higher doses, respectively, which reached below determination limit of 0.05 μg g⁻¹ on the 20^th and 30^th day with corresponding half life of 3.45 and 3.55 days. Soil samples analysed on the 15^th day after the last application revealed presence of only tebuconazole residues at 0.075 and 0.167 μg g⁻¹ at standard and higher doses, respectively.