Prevalence and Virulence of Fusarium spp. Associated with Stalk Rot of Corn in Colorado. Robert L. Gilbertson, Former Graduate Research Assistant, Department of Plant Pathology and Weed Science, Colorado State University, Fort Collins 80523. William M. Brown, Jr., Associate Professor, Department of Plant Pathology and Weed Science, Colorado State University, Fort Collins 80523, and EARL G. Ruppel, Research Plant Pathologist, U.S. Department of Agriculture, Agricultural Research Service, Crops Research Laboratory, Colorado State University, Fort Collins 80523. Plant Dis. 69:1065-1068. Accepted for publication 2 July 1985. 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, 1985. DOI: 10.1094/PD-69-1065.

Stalk rot caused by Fusarium spp. was the most prevalent type of stalk-rot disease found in 1982 and 1983 in Colorado. Fusarium stalk rot, caused by F. moniliforme and F. subglutinans, and Gibberella stalk rot, caused by F. graminearum (teleomorph: Gibberella zeae), were detected in 1982, whereas Fusarium stalk rot and charcoal rot, caused by Macrophomina phaseolina, were detected in 1983. Virulence tests of stalk-rot Fusarium spp. from different sources (corn seed, stubble, stalks, soil, and air) and locations in Colorado in 1983 indicated that F. graminearum isolates were more virulent than F. moniliforme and F. subglutinans isolates, regardless of source. F. moniliforme and F. subglutinans were similar in ability to cause stalk rot; F. subglutinans is an important stalk-rot fungus in Colorado. Results from isolation studies revealed that corn stubble provides an overwintering site for pathogenic stalk rot and saprophytic Fusarium spp. in Colorado.