Identification and distribution of 'Botryosphaeria' spp. associated with grapevine cankers in the grape-growing areas of New South Wales and South Australia

Botryosphaeria spp. are now recognised as important pathogens of grapevines, both in Australia and overseas. Entry of these species via pruning wounds and the initiation of canker formation in the vascular tissue of the vine results in a slow decline and dieback often described as 'dead arm'. Vascular damage to the xylem results in the loss of spur positions along the cordon, a feature which is accentuated by the progression of the disease basipetally towards, and eventually down the trunk of the vine. Information on the role of these fungi in grapevines in Australia is currently limited, and a field survey comprising vineyards throughout the major grape-growing regions of New South Wales and South Australia was conducted in order to determine the occurrence of Botryosphaeria sp. in these regions. Botryosphaeria spp. were the most commonly isolated fungi, and morphological and molecular identification revealed the presence of at least five species on grapevines in these regions; B. obtusa, B. rhodina, B. stevensii, B. dothidea, and B. parva. Other pathogens isolated from field samples included Eutypa lata, Phomopsis viticola, Phaeomoniella sp., Phaeoacremonium sp. and the bunch rot pathogens Greeneria uvicola and Colletotrichum spp.