Persistence of Monocrotophos Residues In/On Groundnut Plant.

Initial deposits of monocrotophos sprayed at 0.03 and 0.05 per cent, on groundnut plants were 7.2 and 10.3 ppm, respectively. One day after first application, the residues decline to 5.6 and 7.2 ppm resulting in 19 and 26 per cent loss at 0.03 and 0.05 per cent doses, respectively. The amount of residues were 1.6 and 2.0 ppm after seven days. The loss in residues after 15 days was 99 and 97 per cent for the two doses. The respective terminal residues were 0.09 and o.16 ppm in leaves and 0.04 and 0.05 ppm in oil. The half life (RL 50) of monocrotophos after the second spray has 3.3 and 3.6 days, respectively. The maximum time required for the insecticide residue to reach the maximum residue limit (MRL) of 0.2 ppm was 17.5 and 20.5 days.