Analysis of Weather and the 1980 Blue Mold Epidemic in the United States and Canada. J. M. Davis, Associate Professor of Meteorology and Plant Pathology, North Carolina State University, Raleigh 27650. C. E. Main, Professor of Plant Pathology, and R. I. Bruck, Assistant Professor of Plant Pathology, North Carolina State University, Raleigh 27650. Plant Dis. 65:508-512. Copyright 1981 American Phytopathological Society. DOI: 10.1094/PD-65-508.

Tobacco blue mold (Peronospora tabacina) occurred in major tobacco production areas in North America during 1980. Blue mold in the field was first reported on 1 January in Cuba and Jamaica, 5 February in Haiti, 25 February in Honduras, 4 March in Nicaragua, 8 April in Florida, 28 April in South Carolina, 11 May in North Carolina, 30 May in Virginia, 10 June in Maryland and Tennessee, 8 July in Kentucky, 11 July in Pennsylvania, 13 July in Connecticut and Massachusetts, 23 July in Indiana, 25 July in Ohio, and 5 August in Canada. Rainfall in the eastern United States was above normal from March through May and below normal for June through August 1980. Temperatures were below normal in March, April, and June, slightly above normal in May, and well above normal in July and August. Compared with 1979, 1980 was generally warmer and drier but was cooler and wetter in March. Weather conditions were less favorable for blue mold development in 1980 than in 1979, therefore resulting in one-third less loss from this weather-sensitive disease.