Hexythiazox (trans-5-(4-chlorophenyl)-N-cyclohexyl-4-methyl-2-oxothiazolidine-3 carboxamide) is a selective acaricide which is used to control the mite pests in different crops. Okra (Abelmoschus esculentus) is an important vegetable crop under malvaceae family.One of the major constrain of okra cultivation is the infestation of the crop with different mites which cause a considerable yield loss. As hexythiazox is newly introduced, no systemic study on the persistence of the chemical in vegetable crop like okra is available under Indian agroclimatic condition. This prompted the present investigators to conduct a multi location supervised field experiment in okra at three different agroclimatic zones of India where hexythiazox was applied @ 25 g and 50 g a.i.ha-1. Okra fruit samples are collected at 0(2 hr), 1, 3, 5, 7, 10 days and Soil samples were collected at 0(2 hr) and 10 days after the application of the chemical. Hexythiozox residues were extracted and cleaned up according to QuEChERS method and quantified by GC - ECD. At fortification levels of 0.01, 0.05, and 0.1mg kg-1, the recoveries ranged from 85.6 - 92.4 % in okra fruit and 82.0 - 90.2 % in soil. The LOQ was found to be 0.01mg kg-1. The initial deposit of Hexythiazox in okra fruit ranged from 0.39 - 0.61 ppm at location-I, 0.45 - 0.70 ppm at location-II and 0.20 to 0.36 ppm at location-III respectively. Around 60-70% of initial residue was dissipated by 3rd day. The residue of hexythiazox was below the quantification level of 0.01 ppm by 10th day for both the doses. The dissipation half-life of hexythiozox in okra ranged from 1.65 - 1.92 days. No residue of hexythiazox was quantified in soil at harvest. According to the CODEX MRL 0.05 mg kg-1, the preharvest interval (PHI) of hexythiozox in okra fruit ranged from 3 � 5 days after the treatment.

Degradation dynamics of hexythiazox in okra (Abelmoschus esculentus)

248th National Meeting (2014)

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