Methods of Screening Rices for Varietal Resistance to 'Cercospora' Leaf Spot

摘要

Autoclaved rice stem nodes with prune juice provide a favorable medium for the isolation of Cercospora Oryzae, the fungus causing Cercospora leaf spot on narrow brown leaf spot, and for the mass production of spores. Spraying of spores in late afternoon resulted in good infection on plants in the field. As shown by artificial inoculation, rice at different stages of growth is susceptible to C. oryzae. An incubation period of 20 days is necessary before the first few lesions appear and 30 days before the maximum number of lesions is reached. A method of artificial inoculation for screening varieties for resistance and a disease scale of 0 to 9 units, based upon the number of lesions, are suggested.