KATNA, SAPNASINGH, SHUBHRA2017-09-282017-09-282017-09http://krishikosh.egranth.ac.in/handle/1/5810031925ABSTRACT The present investigations on “Persistence of acephate, chlorpyriphos, quinalphos and triazophos in cucumber” was carried out during 2016-2017 in the department of Entomology, Dr. Y S Parmar University of Horticulture and Forestry, Nauni, Solan. The objectives of the study were to evaluate the persistence of acephate, chlorpyriphos, quinalphos and triazophos in cucumber fruits, effect of processing on residues and the accumulation of insecticides in the soil. The persistence study on cucumber fruits recorded initial deposits due to single dose of acephate (560 g a.i. ha-1), chlorpyriphos (300 g a.i. ha-1), quinalphos (250 g a.i. ha-1) and triazophos (300 g a.i. ha-1) as 0.640, 0.980, 0.628 and 0.985 mg kg-1, respectively. However, at double dose the initial deposits were 1.123, 1.860, 1.126 and 1.906 mg kg-1 for respective insecticides. The initial deposits of 0.076, 0.112, 0.189 and 0.098 mg kg-1 at single dose and 0.161, 0.198, 0.146 and 0.189 mg kg-1 at double dose were observed for acephate, chlorpyriphos, quinalphos and triazophos, respectively, in cucumber cropped soil. Acephate and quinalphos residues persisted in cucumber fruits upto 5 and 7 days at single and double dose, respectively. Whereas, chlorpyriphos and triazophos persisted for 7 days at recommended dose and 10 days at double the recommended dose. The residues of acephate, chlorpyriphos, quinalphos and triazophos in fruits reduced to half in less than 2 days. The waiting periods for the respective insecticides were worked out at their limit of determination (0.05 mg kg-1) due to lack of MRL value in India. The safe waiting periods on cucumber were suggested as 9, 10, 8 and 11 days for acephate, chlorpyriphos, quinalphos and triazophos, respectively. Among various decontamination processes, peeling was found most effective which provided upto 91.36 per cent relief followed by vinegar dipping (71.60 per cent), saline water dipping (56.49 per cent), lukewarm water washing (40.34 per cent) and tap water washing (30.74 per cent) from insecticide residues in cucumber.ennullThesis