Abstract
The present study was conducted to identify the causal fungi of ear blighting of rice plant, to make clear the relation between leaf blade infection and ear blighting, and to determine the proper timing of EDDP application for the control of ear blighting.
1. A large number of ear blighting samples were collected to determine the kind of causal fungi throughout Aichi Prefecture from 1967 to 1970. Main species detected were Helminthosporium sp., Cladosporium sp., Pyricularia sp., Cercospora sp., etc. Helminthosporium sp. and Cladosporium sp. were generally found on almost all the samples, while Pyricularia sp. and Cercospora sp. varied in their incidence with the locality or with the year. Cladosporium sp. has not been recognized to be pathogenic to rice plant. It is supposed, therefore, that Helminthosporium sp. is the most important causal fungus of ear blighting in Aichi Prefecture.
2. Distinct correlation was not found between the leaf blade infection with Helminthosporium oryzae and the incidence of ear blighting under the field condition. In the concrete pot experiment, however, both leaf and ear infection with Helminthosporium oryzae was increased with the decrease of root vitality induced by the reductive condition of soil.
3. The ear blighting was effectively controlled by the application of EDDP spray from full heading stage to dough-ripe stage.
