Dissipation kinetics of spinosad from tomato under sub-tropical agro-climatic conditions

The dissipation of spinosad in/on tomato and soil was studied at Indian Agricultural Research Institute, New Delhi, under field condition. The optimized sample preparation technique using high performance liquid chromatography (HPLC) with UV detector gave the limit of quantification (LOQ) of 0.05 μg g(-1) of tomato. Spinosad residues were below the determination limit in/on tomato fruits after 15 days of application for recommended dose (51 g a.i. ha(-1)). The half-life of spinosad was in between 3.18 to 3.74 days for the recommended dose. Similarly half-life of 4.14 to 4.71 days was observed for double the recommended dose. The study also investigated the persistence of spinosad in soil and it has been found that half-life of spinosad in soil was 5.49 to 6.36 days for the recommended dose and 6.76 to 6.91 days for double the recommended dose. Based on the CODEX-MRL of spinosad (0.3 mg kg(-1)), pre-harvest interval (PHI) was 7.54 days for the recommended dose of spray.