Persistence of Common Pesticides in Leafy Vegetables

Abstract

There is an increasing demand for good quality, safe vegetables in the market. To reduce pesticide residue load on fresh produce pre-harvest interval (PHI) or safe waiting periods have been recommended for vegetables. Also, for every pesticide, Maximum Residue Limits (MRLs) are fixed in each crop during which period the pesticide load in the crop goes below the MRL values. Pre Harvest Interval (PHI) or Waiting Period can be achieved by conducting field trials on crops grown in good agricultural practices. It is the time gap between the last spray and the first harvest of the crops. PHI is crop and pesticide specific, i.e. for each pesticide on each crop it has a different value.Chlorothalonil is a widely used fungicide in vegetables. It is recommended for use in spinach beet for control of leaf spot disease and in onion for control of purple blotch disease.Spinach is one among the world s healthiest vegetables. It is rich in nutrients, vitamins and minerals and also contains health-promoting phytonutrients like beta-carotene, lutein and zeaxanthin.Green onions or spring onions are rich in health promoting factors like minerals, vitamins and phytochemicals.The fate of the pesticides, chlorothalonil and Lambda-cyhalothrin needs to be evaluated in leafy vegetables so that their safe use can be recommended. Also, it is required to explore ways to reduce its residues in leafy vegetables after the pests have been controlled. Arka Microbial Consortia (AMC) developed at IIHR has shown excellent results in increasing vegetative growth of vegetables, thus the hypothesis that the same can be used to reduce the residues of pesticides in leafy vegetables by residue dilution . Similarly domestic methods e.g. washing and cooking may reduce the residues of these pesticides but the extent of such reduction is not known. Experimental data will therefore be generated to determine the reduction of residues in leafy vegetables by employing the above means. newline