Beena KumariSachin Kumari2017-06-032017-06-032012http://krishikosh.egranth.ac.in/handle/1/5810014663A field experiment was carried to study the persistence behaviour in okra and soil underneath and effect of processing on the reduction of residues of bifenthrin in okra fruits . A laboratoy experiment was performed for assessing the leaching potential of bifenthrin at two doses in soil (sandy loam, clay loam and sandy ) and leachate fractions. Bifenthrin (Commercial formulation) @ 25 and 50 g a.i ha -1 was sprayed in the Vegetable Research Farm of Chaudhary Charan Singh (CCS) Haryana Agricultural University (HAU), Hisar on okra crop (variety Varsha Uphar ) at fruiting stage. Samples of okra and soil were collected periodically on 0 (1h), 1, 3, 7, 10, 15, 30 day s after applications and at harvest. In leaching experiment, bifenthrin was applied as 25µg (single dose) and 50 µg (double dose) in different soils packed inplexi glass columns. Residues were estimated by gas chromatograph equipped with capillary column and electron capture detector (ECD). Per cent recoveries at the for tification levels of 0.10 and 0.25 mg kg -1 in okra fruits and soil were more than 80 per cent depicting validity of methods used for present studies. Limit of quantification for bifenthrin was 0.005 µg ml -1 in okra and soil both. The residues of bifenthr in did not persist for more than 15 days after treatment. Dissipation followed the first order kinetics showing half -life value of 1.58-2.18 day s for single and double dose, respectively . The per cent reduction of bifenthrin residues by washing was 22.91 -36.71 and 21.50-40.00 at single and double dose, respectively . Washing followed by boiling was found more effective in reducing the residues from 64.58-68.42 pe r cent. Bifenthrin persisted in soil upto 7 day s in single dose and 15 day s for double dose with quite low residues. A leaching experiment was carried out under laboratory conditions . The residues of bifenthrin were retained in three different soils from 85 to 99 per cent in 0-10 cm soil core showing their immobility in soil. As residues of bifenthrin were not detected in any of the leachate fractions of any soil and doses, hence considered safe for ground water .enPersistence, Bifenthrin, Dissipat ion, Half - life period, Processing, Okra, Soil, LeachingThesis