The Diatrypaceae occur worldwide and comprise a number of pathogens of woody crops, forest and ornamental tree species. Despite the taxonomic difficulties within this family, interest in the Diatrypaceae has increased recently, mainly due to the recent detection of these fungi in the premium grape growing regions of California. In the present study, we investigated the diversity and host range of diatrypaceous fungi from prominent wine grape growing regions in South Australia, New South Wales and Western Australia. Approximately 100 isolates were collected from grapevine and other woody plants and compared with reference collections from the United States and Europe. Phylogenetic analyses of the complete sequence of the internal transcribed spacer (ITS) region of the ribosomal DNA and partial sequence of the β-tubulin gene, combined with morphological analyses separated 12 species. These included the previously described species Cryptovalsa ampelina, C. rabenhorstii, Diatrype brunneospora, Eutypa lata, E. leptoplaca, Eutypella australiensis, E. citricola, a Cryptosphaeria sp. and a Diatrype sp., whereas Diatrypella vulgaris, Eutypella cryptovalsoidea and E. microtheca are described as new. Seven species were isolated from grapevine but the prevalence of Diatrypaceae in grapevine cankers varied among the regions surveyed. In many instances in WA and NSW, these newly reported fungi were more widespread and abundant than E. lata. This study provides new information to assist with diagnosis of the causal agents of dieback and canker diseases in Australia and development of management strategies. Further studies to characterize the pathogenicity of diatrypaceous species to grapevines and to elucidate the biology of these fungi are underway.

Eighteen different fungal species were isolated from symptomatic wood of olive trees (Olea europaea) affected by twig and branch dieback in California and identified by means of morphological characters and multigene sequence analyses of the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2), a partial sequence of the β-tubulin gene, and part of the translation elongation factor 1-α gene (EF1-α). These species included Diaporthe viticola, Diatrype oregonensis, Diatrype stigma, Diplodia mutila, Dothiorella iberica, Lasiodiplodia theobromae, Phaeomoniella chlamydospora, Phomopsis sp. group 1, Phomopsis sp. group 2, and Schizophyllum commune, which are for the first time reported to occur in olive trees; Eutypa lata, Neofusicoccum luteum, Neofusicoccum vitifusiforme, and Phaeoacremonium aleophilum, which are for the first time reported to occur in olive trees in the United States; and Botryosphaeria dothidea, Diplodia seriata, Neofusicoccum mediterraneum, and Trametes versicolor, which have been previously reported in olive trees in California. Pathogenicity studies conducted in olive cultivars Manzanillo and Sevillano showed N. mediterraneum and Diplodia mutila to be the most virulent species and Diatrype stigma and D. oregonensis the least virulent when inoculated in olive branches. Intermediate virulence was shown for the rest of the taxa. This study demystifies the cause of olive twig and branch dieback and elucidates most of the fungal pathogens responsible for this disease in California.

Grapevine trunk diseases are a major concern to the wine-and table-grape industries worldwide, limiting both vineyard longevity and productivity. Field surveys conducted throughout the grape-growing regions of Arkansas and Missouri revealed the presence of three economically important grapevine trunk diseases including, Botryosphaeria canker, Eutypa dieback and esca. Morphological studies along with multi-gene phylogenetical analyses confirmed the identification of 15 different fungal taxa associated with different vascular symptoms. These include Botryosphaeria dothidea, Diatrypella sp.

Field surveys recently conducted in California and in other grape-growing regions in the United States showed Phomopsis viticola to be one of the most prevalent fungi isolated from grapevine perennial cankers in declining vines. The current study has not only confirmed the presence of P. viticola from grapevine cankers in California but also has for the first time revealed the occurrence of Diaporthe ambigua, D. eres, and D. neotheicola in symptomatic grapevine wood in California by means of morphological studies and multi-gene sequence analysis. Pathogenicity trials conducted on mature cordons of Vitis vinifera ‘Syrah’ and ‘Red Globe’, as well as on lignified Syrah dormant canes, showed P. viticola isolates from California to be capable of causing perennial cankers. Lengths of vascular discoloration caused by P. viticola were similar to those caused by Eutypa lata and several Botryosphaeriaceae spp., which are well-known grapevine trunk disease pathogens. Additionally, a lack of spring growth was commonly observed in dormant canes inoculated with P. viticola spore suspensions in two pathogenicity trials. As part of this study, V. vinifera ‘Cabernet Sauvignon’ and ‘Zinfandel’ wood was shown to be more susceptible to infection by P. viticola than ‘Barbera’, ‘Chardonnay’, ‘Merlot’, and ‘Thompson Seedless’ wood. After more than 40 years overlooking P. viticola as a grapevine wood pathogen, this study provides strong evidence of the role of P. viticola as a canker-causing organism, and suggests its addition to the fungi involved in the grapevine trunk disease complex. Results from this study suggest D. ambigua and D. neotheicola to be saprophytes or weak pathogens on grapevine wood.