Variation in Phomopsis Recorded on Grapevine in Australia and Its Taxonomic and Biological Implications

Abstract

Phomopsis viticola is the cause of cane and leaf blight of grapevines. We examined 63 isolates obtained from a survey of 50 vineyards in New South Wales, Victoria, South Australia, Western Australia and Tasmania, from collections in the New South Wales Agriculture Plant Pathology Herbarium, and from vine specimens from a further 36 vineyards. Two distinct taxa (Taxa 1 and 2) of Phomopsis were found, based on alpha spore morphology, appearance of the pycnidium, cirrhus colour, rate of mycelial growth and sporulation in vitro. Minor taxa (Taxa 3 and 4) were found also. Of the isolates studied, 26 were of Taxon 1 and 33 of Taxon 2. Taxon 1 occurred predominantly in coastal vineyards and Taxon 2 in inland vineyards. Studies of isolates representing the different taxa indicated variability in host response, pectic enzyme profile and temperature for optimum spore germination. These criteria confirmed the morphological grouping of the isolates. Isolates DAR 69489, DAR 69457, DAR 69458 and DAR 69484 were designated as representative isolates of Taxa 1, 2, 3 and 4, respectively. Taxon 1 fits the current taxonomic description of Phomopsis viticola (Sacc.) Sacc. Taxon 2 may resemble the species named Fusicoccum viticolum Reddick, or be a variety of P. viticola (Sacc.) Sacc. or a distinct species of Phomopsis. The widespread occurrence of Phomopsis in Australia and the presence of different taxa in the different viticultural regions are demonstrated.