DNA phylogeny, morphology and pathogenicity of Botryosphaeria species on grapevines

Several species of Botr yosphaeria are known to occur on grapevines, causing a wide range of disorders including bud mortality, dieback, brown wood streaking and bunch rot. In this study the 11 Botryosphaeria spp. associated with grapevines growing in various parts of the world, but primarily in South Africa, are distinguished based on morphology, DNA sequences (ITS-1, 5.8S, ITS-2 and EF1-) and pathological data. Botryosphaeria australis, B. lutea, B. obtusa, B. parva, B. rhodina and a Diplodia sp. are confirmed from grapevines in South Africa, while Diplodia porosum, Fusicoccum viticlavatum and F. vitifusiforme are described as new. Although isolates of B. dothidea and B. stevensii are confirmed from grapevines in Portugal, neither of these species occurred in South Africa, nor were any isolates of B. ribis confirmed from grapevines. All grapevine isolates from Portugal, formerly presumed to be B. ribis, are identified as B. parva based on their EF1- equence data. From artificial inoculations on grapevine shoots, we conclude that B. australis, B. parva, B. ribis and B. stevensii are more virulent than the other species studied. The Diplodia sp. collected from grapevine canes is morphologically similar but phylogenetically distinct from D. sarmentorum. Diplodia sarmentorum is confirmed as anamorph of Otthia spiraeae, the type species of the genus Otthia (Botryosphaeriaceae). A culture identified as O. spiraeae clustered within Botryosphaeria and thus is regarded as probable synonym. These findings confirm earlier suggestions that the generic concept of Botryosphaeria should be expanded to include genera with septate ascospores and Diplodia anamorphs

Temporal susceptibility of grapevine pruning wounds to trunk pathogen infection in South African grapevines

Eutypa lata and Phaeomoniella chlamydospora, as well as several species in Botryosphaeriaceae, Phomopsis and Phaeoacremonium are known trunk pathogens of grapevines, which use pruning wounds as infection portals. Duration of pruning wound susceptibility to some of these pathogens was largely unknown. To address this question, plants of the cv. Chenin Blanc in a vineyard in the Stellenbosch area of South Africa were pruned at two stages, and then spray-inoculated with spore suspensions of E. lata, Pa. chlamydospora, Neofusicoccum australe and Phomopsis viticola directly after pruning, and 1, 2, 3, 7, 10, 14, 17 and 21 days after pruning. Eight months after inoculation, pathogen incidence in the treated wounds was determined by means of isolation from the pith and xylem tissue of treated plants. Lesions observed in these tissues were also measured and recorded. Results indicated that, irrespective of pathogen inoculated, pathogen incidence in the inoculated pruning wounds of both mid- and late winter declined with increasing wound age. The rate of decline was much slower in 2004 compared to 2005; however, wounds remained susceptible for 3 or more weeks after pruning in both years. Late winter wounds were more susceptible to infection than wounds made earlier in the season, while xylem tissue of pruning wounds generally proved more susceptible to all pathogens compared to exposed pith tissue

Botryosphaeria spp. as grapevine trunk disease pathogens

Several species of Botryosphaeria, including Botryosphaeria dothidea, B. obtusa, B. parva and B. australis, were isolated and/or described from declining grapevines in association with a wide range of decline and dieback symptoms. Internal wood symptoms most commonly included black streaking, wedge-shaped necrosis and brown internal necrosis. Several diseases under names such as excoriose, grapevine decline syndrome and black dead arm have been described for decline and dieback symptoms associated with Botryosphaeria. This has led to the confusing situation where the same symptoms and causal species are often associated with more than one disease. This review summarises the research on Botryosphaeria on grapevine by focusing on the causal species, their associated symptoms, known epidemiology and possible effective control and management strategies

First Report of Lasiodiplodia crassispora as a pathogen of grapevine trunks in South Africa

In 2003 and 2004, a survey of grapevine (Vitis vinifera L.) trunk pathogens was conducted in 30 vineyards in the Western and Northern Cape and Limpopo provinces of South Africa. In each vineyard, 20 visually healthy plants were sampled randomly by removing the distal part of one cordon arm. Isolations were made onto potato dextrose agar (PDA) from the internal wood decay symptoms observed in the cordon samples. Seven Botryosphaeriaceae spp. were identified, including Lasiodiplodia crassispora (1). Other Botryosphaeriaceae spp. are known grapevine trunk pathogens (2). Species identity was confirmed by DNA sequence data of the partial translation factor 1-a gene (1) and sequences deposited in GenBank (GU233658 and GU233659). The L. crassispora isolates (CBS 125626 and 125627) were associated with brown internal necrosis, a known symptom of grapevine Botryosphaeriaceae spp. infection (3), in the cordon arms of Ruby Cabernet grapevines occurring in two vineyards in the Northern Cape Province. L. crassispora was described from cankered wood of Santalum album in Western Australia and endophytically from Eucalyptus urophylla in Venezuela (1). Its grapevine pathogen status was determined using both isolates in a repeated pathogenicity test that included three isolates each of Botryosphaeria dothidea and Neofusicoccum australe as positive controls (2), Trichoderma harzianum as a nonpathogen treatment, and an uncolonized agar plug as a negative control. The Botryosphaeriaceae spp. and T. harzianum were plated on PDA and incubated at 25°C for 7 days. Lignified, 6-month-old shoots of grapevine cv. Chardonnay were excised from grapevines with internodes 4 to 6 used for inoculations. Before wounding, shoots were disinfected by submersion for 1 min in a 1 ml/liter solution of a quaternary ammonium compound (Sporekill; ICA International Chemicals (Pty) Ltd, Stellenbosch, South Africa). Twelve shoots were used for each isolate or control treatment. Wounds were made 2 mm deep on the fifth internode of the shoots with a 5-mm flame-sterilized cork borer (2,3). Wounds were inoculated with a pathogen colonized agar plug (5 mm in diameter) or an uncolonized agar plug and then covered with Parafilm (2,3). Inoculated shoots were incubated in the dark in moist chambers for 14 days at 25°C. After incubation, the bark of the shoots was peeled from the area around the wound and the lengths of any resultant lesions were measured under sterile conditions. The inoculum effect was assessed by analysis of variance and Student's t-test. Results showed that significantly (P <0.0001) longer lesions were caused by L. crassispora (13.36 mm) compared with N. australe (9.27 mm) and B. dothidea (5.28 mm) and also significantly longer than lesions caused by the nonpathogen and negative controls (3.23 and 2.90 mm, respectively). To determine if lesions were caused by inoculated fungi, isolations were made from the tissue at the edges of the lesions by aseptically removing five 0.5 × 1 mm pieces of wood and placing them on PDA dishes amended with 0.04 g/liter of streptomycin sulfate. Dishes were incubated under normal fluorescent light at 25°C for 14 days before identifying isolated fungi based on morphological and cultural characteristics (1). To our knowledge, this is the first report of L. crassispora as a grapevine pathogen

The distribution and symptomatology of grapevine trunk disease pathogens are influenced by climate

Grapevine trunk diseases, caused by a range of phytopathogenic fungi, represent a serious impediment to wine and table grape production wherever these crops are cultivated. Previous studies have shown that the distribution of these pathogens is influenced by climate and that they are associated with a variety of internal wood decay symptoms. Little was known, however, about the influence of climate on the disease symptomatology of the different pathogens in a specific area. To address this, a survey was conductedin 30 wine and table grape vineyards in summer, marginal and winter rainfall regions of South Africa. Apart from Eutypa lata, which occurred only in the winter rainfall region, Phaeomoniella chlamydospora, species of Phaeoacremonium, Botryosphaeriaceae and Phomopsis occurred in all regions surveyed. The incidence of the fungal genera and species associated with trunk disease varied between regions, with overlapping symptom profiles that differed based on the climatic region. These findings suggest that symptom-based disease diagnosis alone is unreliable and that distribution and symptomatology of grapevine trunk pathogens are strongly influenced by climatic conditions in a specific production region.

First report of lasiodiplodia crassispora as a pathogen of grapevine trunks in South Africa

[No abstract available]Articl

DNA phylogeny, morphology and pathogenicity of Botryosphaeria species on grapevines

Several species of Botryosphaeria are known to occur on grapevines, causing a wide range of disorders including bud mortality, dieback, brown wood streaking and bunch rot. In this study the 11 Botryosphaeria spp. associated with grapevines growing in various parts of the world, but primarily in South Africa, are distinguished based on morphology, DNA sequences (ITS-1, 5.8S, ITS-2 and EF1-α) and pathological data. Botryosphaeria australis, B. lutea, B. obtusa, B. parva, B. rhodina and a Diplodia sp. are confirmed from grapevines in South Africa, while Diplodia porosum, Fusicoccum viticlavatum and F. vitifusiforme are described as new. Although isolates of B. dothidea and B. stevensii are confirmed from grapevines in Portugal, neither of these species occurred in South Africa, nor were any isolates of B. ribis confirmed from grapevines. All grapevine isolates from Portugal, formerly presumed to be B. ribis, are identified as B. parva based on their EF1-α sequence data. From artificial inoculations on grape-vine shoots, we conclude that B. australis, B. parva, B. ribis and B. stevensii are more virulent than the other species studied. The Diplodia sp. collected from grapevine canes is morphologically similar but phylogenetically distinct from D. sarmentorum. Diplodia sarmentorum is confirmed as anamorph of Otthia spiraeae, the type species of the genus Otthia (Botryosphaeriaceae). A culture identified as O. spiraeae clustered within Botryosphaeria and thus is regarded as probable synonym. These findings confirm earlier suggestions that the generic concept of Botryosphaeria should be expanded to include genera with septate ascospores and Diplodia anamorphs.Articl