Influence of Tillage on Development of Gray Leaf Spot and Number of Airborne Conidia of Cercospora zeae-maydis. G. A. Payne, Associate Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. H. E. Duncan, and C. R. Adkins. Professor, and Research Assistant, Department of Plant Pathology, North Carolina State University, Raleigh 27695-7616. Plant Dis. 71:329-332. Accepted for publication 6 November 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-0329.

Four tillage treatments (fall plow, spring disk; fall disk, spring plow, spring disk; spring plow, spring disk; and no-till) were compared for their influence on development of gray leaf spot and numbers of airborne conidia of Cercospora zeae-maydis. The effects of tillage were similar for 1983 and 1984, but 1983 was a hot, dry season in which little disease developed. In 1984, conidia were first trapped on 23 May, 5 days after planting, but collection was erratic. Levels of airborne conidia increased beginning on 27 July in all the plots, with the greatest number of conidia collected in the no-till plots. Lesions appeared earlier (2 wk before silking) and disease was greater at each evaluation date in the no-till plots than in the other plots. By 12 September, the numbers of lesions on the fifth leaf above the ear averaged 72 for the no-till plots and 36 for the other tillage plots. There were no differences in disease severity among the other treatments. Yield was significantly less in the no-till plots than in the other plots.