Residue dynamics of combi product Lancergold® (acephate 50% + imidacloprid 1.8%) on okra and in soil

Abstract

Lancergold® (Acephate 50% and imidacloprid 1.8%) a combi product of UPL was sprayed on okra at two different dosages viz., single dose (X) i.e 1000g a.i./ha and at the double dose (2X) i.e. 2000 g a.i./ha. Okra and soil samples were collected from the day of spray to check the presence of residues in them. The initial deposits of ∑-acephate {Acephate + methamidophos (metabolite of acephate)} on okra fruits were 1.303 and 2.351 mg kg-1 which dissipated below determination limits on 10th and 15th day at X and 2X, respectively. Half-life values (RL50) were calculated to be 2.16 and 2.36 days, at respective doses. However at the same application rates, in soil the initial deposits were 0.291 and 0.442 mg kg-1, respectively which reduced to 0.113 and 0.069 mg kg-1 after 1, 3 and 5 days of spraying at single dose (X) and at the double dose (2X) it declined to 0.442, 0.282, 0.215 and 0.082 mg kg-1 after 1, 3, 5 and 7 days of spraying respectively. The initial deposits of imidacloprid on okra fruits due to the application of Lancergold® @ 1000 and 2000 ga.i. ha-1 were 0.192 and 0.393 mg kg-1, respectively. Initial deposits, at single dose, dissipated to 0.102 mg kg-1 after 1 day and reduced below the determination limit on 3rd day of application whereas at double dose, the initial deposits dissipated to 0.186 and 0.091 mg kg-1 after 1 and 3days of spraying, respectively. Half-life values (RL50) were calculated to be 1.10 and 1.47days, at respective doses, whereas in okra cropped soil initial deposits were 0.051 and 0.247 mg kg-1 on day 0 which declined to Below detection limit BDL on 1st and 3rd day of application at respective doses.