Bentgrass dead spot caused by Ophiosphaerella agrostis in Japan

Abstract

A new disease was found on creeping bentgrass (Agrostis stolonifera) putting greens on golf courses in Shizuoka and Chiba prefectures in Japan, from late spring through early autumn in 1999. Symptoms showed brown, reddish-brown and tan color spots ranging from 1 to 5 cm in diameter on putting greens. Diseased plants were wilted and dead without any lesions on leaf blade. Pale brown pigmented ectotrophic hyphae were consistently observed on leaf blade and sheath. A specific fungus was always isolated from leaf blade and sheath. Optimal growth temperature of the fungus on potato-sucrose agar was 25°C. Extremely high pathogenicity was found on creeping bentgrass. The pathogenicity of the fungus on perennial ryegrass (Lolium perenne) and hybrid bermudagrass (Cynodon dactylon×C.transvaalensis) was also high. Based on morphological characteristics of pseudothecia, asci and ascospores, the fungus was identified as Ophiosphaerella agrostis Dernoeden, Câmara, O'Neil, van Berkum & Palm. We concluded that the name of the new disease of creeping bentgrass caused by O. agrostis in Japan is regarded as‘Dead spot’ (dead spot-byo in Japanese) .