Division of Entomology, Indian Agricultural Research Institute, New Delhi-110 012
Three sprays of 0.03% and 0.05% methamidophos were given at the rate of 0.33 and O.55 kg ai/ha at the time of pest population build up. Samples of leaves and flowers/curds were collected at 0,3,7, 14 and 21 days after spray application. The residues were estimated by bioassay and chemical methods.
The studies by bioassay method indica that the time takcn by the rcsidues to reach below the maximum residue limit (TMRL) were found to range from 3 to 6 days for curd and 5–9 days for leaves at 0.03% concentration. The TMRL value ranged from 8 to 12 days for curd and 6 to 14 days for leaves at 0.05% concentrati At the initial stages of treatment, the rcsi-dues estimated biologically and chemically were of the same magnitude but at the later part of the treatment, chemical estimates were higher 1than biological estimates.
