Endophytic fungi associated with shoots and leaves of Vitis vinifera, withspecific reference to the Phomopsis viticola complex

Phomopsis cane and leaf spot caused by Phomopsis viticola is an economicall y important disease in many of the vine-growing areas of the world. The aim s of this study were to investigate whether P. viticola grows endophyticall y in various vine tissues, and to monitor its distribution over the growing season. Asymptomatic shoots were collected at eight different growth stage s. Nodes, internodes, leaf petioles, leaves, tendrils and bunch rachides we re surface sterilised, cut into smaller pieces and plated out on potato dex trose agar. After the fungal endophytes were identified, the relative impor tance (RI) values were calculated and a correspondence analysis performed o n the data of taxa with RI larger than 5%. Of the 46 different fungal taxa found. 20 were present at relative importance values of more than 1%. An an alysis of the relative importance of the different species showed that the most frequently isolated fungi were members of the Alternaria alternata com plex (40%) and Sphaeropsis sp. (27%). The Phomopsis viticola complex had a relative importance of 9% and accounted for 3% of the isolations. P. vitico la was mainly isolated from the nodes and internodes, the plant parts in wh ich I? viticola usually causes disease symptoms. Two different Phomopsis sp p. were isolated, with 94% of the isolates representing P. viticola taxon 2 , and the rest taxon 1. Isolations made from diseased vine material during the last two years revealed taxon 2 to be dominant in vineyards in the West ern Cape. Inoculations into healthy, young vine tissue also showed taxon 2 to be a primary pathogen, further suggesting that it is probably a latent p athogen rather than an endophyte. In contrast, taxon 1 appears to be a true endophyte, and does not seem to be an important pathogen on vines.