First report of blast disease caused by <i>Pyricularia oryzae</i> on creeping bentgrass in Japan

Abstract In August 2008, a patch disease of creeping bentgrass ( Agrostis stolonifera L.) was discovered at golf courses in Shizuoka and Kyoto, Japan. The disease occurred in dark brown patches that ranged from several to 10 cm in diameter. Affected plant individuals within the patch exhibited dark brown leaf blight and withering. Pyricularia fungi, which cause blast disease in grasses, were observed, and two strains were obtained from the affected plants. Based on the morphological characteristics and the nucleotide sequences of internal transcribed spacer regions with 5.8S ribosomal DNA and the β‐tubulin gene, they were identified as Pyricularia oryzae . For pathogenicity tests, the strain was grown in a soil‐bran medium and inoculated to creeping bentgrass plants grown in pots. As a result, many spindle‐shaped lesions were formed on the leaves, which later showed leaf blight and plant withering. Inoculation was made in the same manner as for other grass species, and the fungus showed pathogenicity on colonial bentgrass, perennial ryegrass, tall fescue, and Kentucky bluegrass. In conclusion, this is the first report of blast disease of creeping bentgrass by P. oryzae in the world, which has a wide host range in gramineous plants.