The Role of Bipolaris oryzae in Floral Abortion and Kernel Discoloration in Rice. M. A. Marchetti, Research Plant Pathologist, Agricultural Research Service, USDA, Texas A&M University Agricultural Research and Extension Center, Beaumont 77706. H. D. Petersen, Regional Biometrician, Agricultural Research Service, USDA, Veterinary Toxicology and Entomology Laboratory, Texas A&M University, College Station 77841. Plant Dis. 68:288-291. Accepted for publication 27 September 1983. 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, 1984. DOI: 10.1094/PD-68-288.

Foliar symptoms of brown spot (caused by Bipolaris oryzae) were modified in field plots by the presence of a rice line that promotes spreading of the disease and by the use of fungicides. There was no correlation between brown spot symptoms and floral abortion, and kernel discoloration was moderately correlated with brown spot. In this study, panicle blight, a disease of unknown etiology, was the primary cause of floral abortion and rice stink bug feeding was the major factor in kernel discoloration. It was concluded that B. oryzae was a secondary invader of aborted florets, that it was possibly the primary cause of some kernel discoloration, and that it was just one of many microbes that colonized kernels through stink bug feeding wounds.

Keyword(s): Helminthosporium oryzae, Oebalus pugnax, Oryza sativa, peck.