*Division of Entomology & Nematology, Central Potato Research Institute, Shimla, 171 001
Department of Bio-Sciences, Himachal Pradesh University, Summer Hills, Shimla, 171 005, (Himachal Pradesh)
** A part of Ph.D thesis of senior author submitted to the faculty of science of Himachal Pradesh University, Summer Hills, Shimla 171 005.
A replicated field experiment was conducted using potato cv. ‘Kufri Jyoti’ during summer potato crop season (April to September) of 1983 and 84 at Shimla, (H.P.) for studying the dissipation of phorate and disulfoton @ 1.0 and 1.5 kg a.i/ha applied to soil i'it two protocols either single or split application. Phorate and disulfoton residues in unprocessed potatoes from 1.0 and 1.5 kg a.i/ha doses persisted above the tolerance limits of 0.5 ppm upto 118 days (except in case of disulfoton) and 118/76 days, after planting and planting/earthing time application of granules respectively. Phorate residues in unprocessed potatoes Were undetectable (<0.02 ppm) from both the doses applied in first protocol but were within the tolerance limit in second protocol. While, disulfoton residues were undetectable in unprocessed potatoes. Residues of both theseinsecticides in processed potatoes and water obtained after cooking were within the tolerance limits.
