報文
北海道におけるイネ赤色菌核病の発生
2016 年 2016 巻 67 号 p. 77-80
詳細
2016 年 2016 巻 67 号 p. 77-80
In Hokkaido, the northern island of Japan, a disease showing spots on rice sheaths, similar to the symptoms of the sheath blight, occurred in September 2013. Salmon pink-colored screlotia in flat shapes were observed on the inside of the diseased sheath. We obtained four isolates of Rhizoctonia-like fungi from four different locations. Artificial inoculation resulted in the four isolates induced spots on rice sheaths,which were similar to the original symptoms, and the fungus was re-isolated from the inoculated plant.These isolates formed salmon pink-colored sclerotia with an irregular shape on potato dextrose agar（PDA）．Hyphal width was 5.5-10.4μm, and 2-13 nuclei per cell were observed microscopically. The optimum temperature for mycelial growth on PDA was ca. 30 ℃. The species-specific primers for Rhizoctonia oryzae yielded the PCR products with the expected length. Based on these properties, the isolates were identified as R. oryzae that was the pathogen of Rhizoctonia sheath spot of rice. This is the first report of Rhizoctonia sheath spot of rice in Hokkaido.
