Fungi associated with dieback of Semillon grapevines in the Hunter Valley of New South Wales

In the Hunter Valley of New South Wales, 180 km north of Sydney, 11 sites i n six vineyards were surveyed for fungi associated with vine decline and di eback symptoms in Semillon grapevines from September 1995 to January 1996. Botryosphaeria obtusa (Schwein.) Shoemaker was detected in affected vines o n most of the sites. Greeneria uvicola (Berk. & M. A. Curtis) Punithalingam and Pestalotiopsis sp. were also commonly isolated but the role of these f ungi in the dieback symptoms remains uncertain. The occurrence of Eutypa la ta (Pers.: Fr.) Tul. & C. Tul. in grapevines exhibiting dieback in the regi on remains unconfirmed. In pathogenicity studies, B. obtusa was shown to ca use internal symptoms such as dark streaking in the wood of inoculated vine s.