Infection Cycle Components and Disease Progress of Gray Leaf Spot on Field Corn. C. E. RINGER, Research Associate, Soil Microbial Systems Laboratory, USDA-ARS, Beltsville, MD 20705-2350. A. P. GRYBAUSKAS, Associate Professor, Department of Botany, University of Maryland, College Park 20742-5815. Plant Dis. 79:24-28. Accepted for publication 28 September 1994. This article is in the public domain and not copyrightable It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1995. DOI: 10.1094/PD-79-0024.

The epidemiology of gray leaf spot disease (GLS) on field corn (Zea mays) was studied following artificial inoculation with the fungus, Cercospora zeae-maydis. Studies were based on relative differences in selected infection cycle components between a susceptible and a moderately resistant corn hybrid. Area under the disease progress curve, apparent infection rate, number of lesions, and sporulation capacity were lower and latent period was longer on the moderately resistant hybrid than on the susceptible hybrid. Based on comparisons of disease progress curves, infection cycle components, and rainfall patterns, it is postulated that rainfall and sporulation during early infection cycles have a significant effect on development of GLS. Management strategies aimed at decreasing levels of inoculum during early infection cycles are suggested as an effective means of reducing the severity of GLS.