Dissipation of Profenofos in/on Tea Leaves

Dissipation of profenofos 50 EC residue was assessed in tea leaves after application at 500 and 1000 g a.i. ha¹ to derive the safe pre-harvest waiting period. Tea leaf samples (250 g) collected from two field trials on 0, 1, 3, 5, 7, 10, 15 and 30 d after the third round of insecticide application gave initial deposits of 3.6271 and 7.1796 μg g⁻¹, respectively in the trial I and 2.8990 and 6.0745 μg g⁻¹, respectively in the trial II. The residues reached below detectable level on the 7^th and 10^th d at the two doses respectively. Half-life of profenofos ranged from 1.20 to 1.40 d. A safe waiting period of 6.5 d is recommended for harvesting the leaves after spraying profenofos @ 500 g a.i ha ¹.