Potential for Zero Residue Disease Control Programs for Fresh and Processed Apples Using Sulfur, Fenarimol, and Myclobutanil. A. L. Jones, Department of Botany and Plant Pathology and the Pesticide Research Center, Michigan State University, East Lansing 48824. G. R. Ehret, M. F. El-Hadidi, M. J. Zabik, J. N. Cash, and J. W. Johnson. Department of Botany and Plant Pathology and the Pesticide Research Center; Department of Entomology and the Pesticide Research Center; Department of Food Science and Human Nutrition; and Department of Entomology, Michigan State University, East Lansing 48824. Plant Dis. 77:1114-1118. Accepted for publication 17 August 1993. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/PD-77-1114.

In 1990 and 1991, efficacy of disease control and fungicide residues in raw and processed products were evaluated for spray programs for scab (Venturia inaequalis) and sooty blotch (Gloeodes pomigena) on three cultivars of apple (Malus × domestica ). Spray programs based exclusively on fenarimol and myclobutanil resulted in suboptimum control of fruit scab and no control of sooty blotch. A spray program of sulfur and one consisting of tebuconazole plus captan resulted in good and excellent control of apple scab, respectively. Both programs provided adequate control of sooty blotch. Residues of fenarimol and myclobutanil in unwashed raw apples and in frozen slices, sauce, and juice concentrate made from washed and peeled apples were far below tolerance levels established by the Environmental Protection Agency. Increasing the interval between the last spray and harvest reduced but did not eliminate residues in processed products. Residues of sulfur were high in unwashed fruit, but at or below detection limits in frozen slices, sauce, and juice made from washed and peeled fruit.