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Techniques

A Technique for Determining the Deposition of Heavy Metals in Pesticides. J. W. Travis, Graduate research assistant, Departments of Plant Pathology and Horticultural Science, North Carolina State University, Raleigh 27695, Present address of senior author: Department of Plant Pathology, The Pennsylvania State University, University Park 16802; T. B. Sutton(2), and W. A. Skroch(3). (2)Associate professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695; (3)Professor, Department of Horticultural Science, North Carolina State University, Raleigh 27695. Phytopathology 75:783-785. Accepted for publication 22 January 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-783.

A technique is described for determining the deposition of pesticides and foliar nutrient materials on apple leaves. The technique is based on the application of a pesticide or foliar nutrient materials that contain heavy metals and the mineral analysis of the metal deposit by atomic absorption spectroscopy. The pesticide was metiram 80W (zinc, 14%) and the foliar nutrient materials were Sequestrene-formulated micronutrients (copper, 13.0%; iron, 10.0%; manganese, 12.0%; zinc, 14.2%). The amount of the compound deposited was calculated in micrograms (active ingredient) per square centimeter of leaf from the percent metal content of the compound and a leaf-dry-weight to surface-area regression equation. By using the technique, laboratory analyses of the deposit agreed closely with calculated deposit levels. The usefulness of the technique in studying pesticide deposition in apple trees depends upon the permanence of the tracer compound and upon the ease and reliability of deposition analysis.