Metalaxyl Controls Blue Mold in Flue-Cured Tobacco Seedbeds. B. A. Fortnum, Assistant Professor, Department of Plant Pathology and Physiology, Clemson University, Pee Dee Experiment Station, Florence, SC 29501. A. S. Csinos, Associate Professor, Department of Plant Pathology, University of Georgia College of Agriculture, Coastal Plain Experiment Station, Tifton 31793; and T. R. Dill, Ciba-Geigy Corporation, Agricultural Division Southeast Regional Office, 5950 Fairview Road, Charlotte, NC 29210. Plant Dis. 66:1014-1016. Accepted for publication 23 February 1982. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-1014.

Early development of blue mold in tobacco (Nicotiana tabacum) plant beds was controlled with the application of 0.28, 0.56, and 1.12 kg a.i. of metalaxyl per hectare at seeding. However, late-season plant bed losses occurred at test sites in Georgia and South Carolina when metalaxyl was applied only at seeding. Foliar application of metalaxyl at 0.28 kg a.i. per hectare at 7- or 14-day intervals completely controlled blue mold. Plants in plots receiving metalaxyl at seeding were susceptible to systemic Peronospora hyoscyami ( = P. tabacina) infection of petioles and stems. An efficacy-rate response existed with treatments applied at seeding and as a foliar spray. Implications of systemic infection in plant beds are discussed.

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