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Etiology

Pathogenicity of Penicillia to Corn Ears. R. W. Caldwell, Former graduate research assistant, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, Present address of the senior author: Department of Plant Pathology, 1630 Linden Drive, University of Wisconsin, Madison 53706; J. Tuite(2), and W. W. Carlton(3). (2)Professor, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907; (3)Professor, Department of Veterinary Microbiology and Pathology, Purdue University, West Lafayette, IN 47907. Phytopathology 71:175-180. Accepted for publication 20 June 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-175.

Eighty-one isolates of 15 Penicillium species were screened for pathogenicity to corn ears. At the full-silk and dent stages, spore suspensions either were injected into the ears at the butt and tip or the silks were sprayed. Injection at full silk was the most effective inoculation procedure. Penicillium oxalicum was pathogenic to corn. It caused lesions on husks, rotted ears, streaked kernels, and reduced germination and invaded over 50% of the kernels on ears injected at full silk. Penicillium brevi-compactum, P. chrysogenum, P. citrinum, P. cyclopium, P. expansum, P. frequentans, P. funiculosum, P. martensii, P. palitans, P. purpurogenum, P. tardum, P. variabile, and P. viridicatum were nonpathogenic. Penicillium funiculosum caused white streaks in the kernel pericarp and invaded over 50% of the kernels on ears injected at full silk, but failed to rot ears or reduce seed viability. The percentage of kernels invaded by the same isolates of eight Penicillium species injected into corn ears at silk 2 yr in succession was not significantly different. Following a 53-day harvest delay, the percentage of kernels invaded by P. brevi-compactum, P. cyclopium, and P. viridicatum (storage species) significantly increased. Penicillium oxalicum colonized and occasionally rotted ears that were artifically injured and spray-inoculated at full silk. Penicillium funiculosum colonized, but did not rot ears. Corn from ears injected at full silk with P. funiculosum and P. oxalicum was not toxic when fed ad libitum to mice.