Abstract
A survey was conducted on the causal fungi of rice ear blighting in Shiga Prefecture during three years from 1967 to 1969. The samples were collected from 67 or 78 locations throughout the Prefecture and the fungi found on their necks and panicle branches were identified by microscopic observation.
The fungi found on the samples were Pyricularia oryzae, Helminthosporium oryzae, Cladosporium cladosporioides, Cercospora oryzae, Nigrospora oryzae, Curvularia lunata, Rhynchosporium oryzae, Fusarium sp., Alternaria sp., Penicillium sp., Aspergillus sp., Epicoccum sp., etc. Some samples were found to be contaminated with two or three species of those fungi.
The most prevalent and widely distributed species were Cladosporium cladosporioides and Pyricularia oryzae, both of which were found on the samples more than 40% and from the locations more than 90%. Helminthosporium oryzae was next to them, and Cercospora oryzae was also widely distributed but with rather low frequency. Curvularia lunata was not popular in its frequency nor distribution.
The panicles infected with Pyricularia oryzae should not be called ear blighting but panicle blast. Cladosporium cladosporioides is known to be non-pathogenic to the panicles of rice plant. Helminthosporium oryzae, therefore, is considered to be the major pathogen of ear blighting in Shiga Prefecture, and Cercospora oryzae, Curvularia lunata and Rhynchosporium oryzae are also concerned with the disease in some occasions.
