Re-Identification of Dollar Spot Pathogen on Creeping Bentgrass and Kentucky Bluegrass in South Korea

Dollar spot is one of the world’s most widely distributed turfgrass diseases. The pathogen of the disease has been re-identified as a fungus belonging to the genus Clarireedia in the United States, Japan, and China. Since Clarireedia species vary depending on the response to fungicides, hosts, and distribution ranges, it is necessary to re-identify dollar spot in South Korea for effective turfgrass management. In this study, the amplified nucleotide sequences with primer sets of the internal transcribed spacer (ITS) region, Calmodulin (CaM), and Mini-chromosome maintenance complex component 7 (Mcm7) were analyzed to re-identify Clarireedia spp. isolated from creeping bentgrass and Kentucky bluegrass on golf courses in South Korea. The ITS and CaM regions were analyzed through multiple sequence alignments. The isolates were identified as C. paspali, and Clarireedia sp. When cultured on PDA, three groups formed fast growing, cottony colonies with white aerial hyphae that later collapsed and turned tan to brown. Most isolates formed apothecia, but ascospores were not observed. The apothecia formation of C. paspali has never been reported. All isolates exhibited pathogenicity on creeping bentgrass and Kentucky bluegrass. These results indicated that the pathogens causing dollar spot on creeping bentgrass and Kentucky bluegrass in South Korea might be C. paspali and Clarireedia sp. The present study reports the first re-identification of the turfgrass dollar spot pathogen Sclerotinia homoeocarpa into the genus Clarireedia in South Korea.