VIEW ARTICLE

Ecology and Epidemiology

Association of Corn Stalk Rot Fusarium spp. and Western Corn Rootworm Beetles in Colorado. R. L. Gilbertson, Former graduate research assistant, Department of Plant Pathology and Weed Science, Colorado State University, Fort Collins 80523, Present address: Department of Plant Pathology, University of Wisconsin, Madison 53706; W. M. Brown, Jr.(2), E. G. Ruppel(3), and J. L. Capinera(4). (2)Associate professor, Department of Plant Pathology and Weed Science, Colorado State University, Fort Collins 80523; (3)Research plant pathologist, U. S. Department of Agriculture, Agricultural Research Service, Crops Research Laboratory, Colorado State University, Fort Collins 80523; (4)Professor, Department of Entomology, Colorado State University, Fort Collins 80523. Phytopathology 76:1309-1314. Accepted for publication 29 May 1986. 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, 1986. DOI: 10.1094/Phyto-76-1309.

Western corn rootworm beetles (Diabrotica virgifera) were abundant on corn ears (Zea mays) in eastern Colorado in 1982, 1983, and 1984. Corn stalk rot fungi Fusarium moniliforme and F. subglutinans were consistently isolated from beetles collected from one site in 1982 and 1984, and two sites in 1983. Fungal contamination of beetles increased as the season progressed, and surface-disinfestation of beetles did not eliminate contamination, indicating internal contamination. In 1983, beetles collected from a corn field were more heavily contaminated by F. moniliforme and F. subglutinans (41%) than beetles collected from a nearby squash field (17%). Populations of beetles on corn ears and amount of kernel contamination by these fungi were correlated positively, suggesting that beetles were vectors of the fungi. Corn kernels from a field corn plot with Fusarium stalk rot and a heavy beetle infestation were more contaminated externally by F. moniliforme and F. subglutinans (73%), than kernels from a plot with no beetle infestation (27%); the difference in kernel contamination was attributed to rootworm beetles. Western corn rootworm beetles may be vectors for these fungi to corn ears and kernels.