Occurrence of the dollar spot disease of bentgrass turf in Japan

Abstract

Dollar sopt disease in Japan was first reported in 1965 as a minor disease of bentgrass, but has now became one of the serious diseases on putting greens of golf courses. In this study, several isolates of the causal pathogen Sclerotinia homoeocarpa from Kagawa, Hyogo and Shizuoka were subjected to the tests of pathogenicity and cultural behaviors.
(1) Inoculation tests with five isolates on creeping bentgrass (cv. penncross) sods in the pots revealed that the disease occurred at 10°C and became severer as the rise of incubation temperature. At 25 and 30°C, the turf was completely withered within 3 days after inoculation.
(2) Host range of the pathogen was determined by inoculation with two isolates on 12 gramineous plants grown on the pots. All of the grasses shown below were heavily attacked at 25°C.
Seedlings: Creeping bentgrass (cv. seaside), Italian ryegrass, Kentucky bluegrass, Perenial ryegrass, Tall fescue, Japanese lawngrass, Bahiagrass, Centipedegrass, Weeping lovegrass Adult plants: Creeping bentgrass (cv. penncross ), Italian ryegrass, Tall fescue, Manila grass, Japanese lawngrass, Bahia grass, Bermudagrass, Weeping lovegrass
(3) Behaviors of mycelial growth of five isolates were compared on 6 cultural agar media. There was no significant differences among isolates in the growth and coloration of submerged mycelia. All isolates produced only sporiferous structure. Mycelial growth on PDA was evident in the range of 5 and 35°C and was maximum at 20-30°C. It was suggested that the strains of the pathogen found in Japan resemble the major strain distributed in USA and Australia.