Change in isolation frequency ofTyphula ishikariensis from turfgrass under snow cover on golf courses

The change in isolation frequency ofTyphula ishikariensis from bentgrass leaves under snor cover on golf courses near Sapporo, Hokkaido was investigated over three consecutive winters.Agrostis palustris Huds. cv. Penncross growing at these sites was severely infested withT. ishikariensis biotype B. Isolation tests showed thatT. ishikariensis biotype B was first isolated 9 to 34 d after snow cover in December–January, and isolation frequency peaked in February–March. The fungus was never isolated from leaves after snowmelt. The behavior ofT. ishikariensis on bentgrass was discussed in terms of winter hardiness of plants and its epidemiology.