Persistence of Acephate and Imidacloprid on Cotton Leaves

Acephate and imidacloprid were applied on cotton using ready-mix SP formulation (Lancer Gold), a combination of acephate 50% + imidacloprid 1.8%, @ 500 and 1000 g ai ha⁻¹ with respect to acephate and @18 and 36 g ai ha⁻¹ with respect to imidacloprid. Residues of acephate declined below detectable level of 0.02 mg kg⁻¹ after 15 and 21 days of applications at single and double dose with t_½ of 2.05 and 1.96 days, respectively. Imidacloprid residues reached below its detectable level of 0.02 mg kg⁻¹ after 5 and 7 days of its application at lower and higher rates of application. The half-life values for imidacloprid were observed to be 1.70 and 2.26 days, corresponding to lower and higher dose of application, respectively.