A survey of diseases of exotic trees in plantations was undertaken in southern and southwestern E... more A survey of diseases of exotic trees in plantations was undertaken in southern and southwestern Ethiopia during 2000 and 2001. Our aim was to ascertain the occurrence and distribution of diseases of major plantation species and to provide a basis for further research. Root, stem and leaf samples were collected from both plantations and trees growing near farms and homesteads in and around Wondo Genet, Munessa Shashemene, Jima, Bedele, Mizan and Menagesha. Armillaria root rot was the most common disease, associated mainly with Pinus patula , but also found on Acacia abyssinica, Cordia alliodoral/ig and Cedrela odorata . Stem cankers associated with ligBotryosphaerial/ig species were common on Eucalyptus globulus, E. salignal/ig and E. citriodora . Stem canker disease associated with a ligConiothyriuml/ig species was commonly observed on E. camaldulensis . Leaf blotch associated with ligMycosphaerellal/ig species was common on E. globulusl/ig in most areas where this species is plante...
Little is known regarding the fungi, especially fungal pathogens, associated with mangroves in Af... more Little is known regarding the fungi, especially fungal pathogens, associated with mangroves in Africa. This includes fungi in the Botryosphaeriaceae that comprise numerous opportunistic, stress-associated pathogens often associated with trees affected by environmental and anthropogenically generated stresses, such as those affecting mangroves. We investigated the occurrence of endophytic Botryosphaeriaceae along the entire distribution of mangroves in South Africa. Asymptomatic branches were collected from ten localities and six mangrove species. Isolates resembling species of Botryosphaeriaceae were identified based on multi-gene sequence data of the internal transcribed spacer regions (ITS), including the 5.8S nrRNA, the beta-tubulin (tub2), partial translation elongation factor 1-alpha (tef1-α), and DNA-directed RNA polymerase II second largest subunit (rpb2) gene regions. Inoculation trials were conducted on healthy branches of Avicennia marina and Bruguiera gymnorrhiza to evalu...
Mangrove trees are continuously under stress due to environmental and/or anthropogenic pressures,... more Mangrove trees are continuously under stress due to environmental and/or anthropogenic pressures, which expose them to attack by pathogens, compromising their survival. Ophiostomatoid fungi cause sap stain and diseases of a wide spectrum of tree species globally. These fungi infect trees through natural, insect, animal and/or human made wounds. During routine surveys of mangrove trees in South Africa, wounds on branches and stems of Avicennia marina were regularly monitored for the presence of ophiostomatoid fungi at ten study sites in the country. The stems of four mangrove species, A. marina, Bruguiera gymnorrhiza, Rhizophora mucronata and Barringtonia racemosa were also wounded and evaluated for the appearance of these fungi. Ophiostomatoid fungi were obtained from the mangrove associate B. racemosa, but not from any of the true mangroves. Analyses of DNA sequence data for the internal transcribed spacer, β-tubulin, calmodulin and translation elongation factor gene regions reveal...
Armillaria root-rot is one of the most serious root diseases of perennial tree crops in tropical ... more Armillaria root-rot is one of the most serious root diseases of perennial tree crops in tropical Africa. The disease was first reported on cacao in Ghana during 1927. It was initially referred to as 'collar crack' due to typical longitudinal cracks that are formed in the bark at the tree collar, as a result of mechanical pressure from fungal fans colonizing the cambium. These fungal fans are typical of species in the genus Armillaria. The pathogen associated with the disease was identified as A. mellea (Valh Ex. Fr.). However, A. mellea is a taxonomic complex that currently includes a number of morphologically indistinguishable species, the true identity of the species causing root-rot on cacao in Africa is thus uncertain. More recent studies have shown that DNA sequence comparisons can effectively differentiate among Armillaria species from Africa with uniform morphologies. In this study we applied a molecular approach to characterize Armillaria isolates associated with roo...
During routine surveys for possible fungal pathogens in the rapidly expanding plantations of Euca... more During routine surveys for possible fungal pathogens in the rapidly expanding plantations of Eucalyptus and Cunninghamia lanceolata in China, numerous isolates of unknown species in the genus Ceratocystis (Microascales) were obtained from tree wounds. In this study we identified the Ceratocystis isolates from Eucalyptus and Cunninghamia in the GuangDong, GuangXi, FuJian and HaiNan Provinces of South China based on morphology and through comparisons of DNA sequence data for the ITS, partial β-tubulin and TEF-1α gene regions. Morphological and DNA sequence comparisons revealed two previously unknown species residing in the Indo-Pacific Clade. These are described here as Ceratocystis cercfabiensis sp. nov. and Ceratocystis collisensis sp. nov. Isolates of Ceratocystis cercfabiensis showed intragenomic variation in their ITS sequences and four strains were selected for cloning of the ITS gene region. Twelve ITS haplotypes were obtained from 17 clones selected for sequencing, differing i...
Identification of fungi and the International Code of Nomenclature underpinning this process, res... more Identification of fungi and the International Code of Nomenclature underpinning this process, rests strongly on the characterisation of morphological structures. Yet, the value of these characters to define species in many groups has become questionable or even superfluous. This has emerged as DNA-based techniques have increasingly revealed cryptic species and species complexes. This problem is vividly illustrated in the present study where 105 isolates of the Botryosphaeriales were recovered from both healthy and diseased woody tissues of native Acacia spp. in Namibia and South Africa. Thirteen phylogenetically distinct groups were identified based on Internal Transcribed Spacer (ITS) rDNA PCR-RFLP and translation elongation factor 1-α (TEF1-α) sequence data, two loci that are known to be reliable markers to distinguish species in the Botryosphaeriales. Four of these groups could be linked reliably to sequence data for formerly described species, including Botryosphaeria dothidea, ...
The Ceratocystis paradoxa complex accommodates a group of fungal pathogens that have become speci... more The Ceratocystis paradoxa complex accommodates a group of fungal pathogens that have become specialized to infect mostly monocotyledonous plants. Four species currently are recognized in this group, including C. paradoxa, which has a widespread distribution and broad host range. In this study, multigene phylogenetic analyses involving sequences of the ITS, β-tubulin and TEF-1α gene loci, in combination with phenotypic and mating studies, were used to characterize purported C. paradoxa isolates from Cameroon and to compare them with isolates from elsewhere, including protologs and type specimens of known species. We show that the C. paradoxa complex comprises substantially greater species diversity than previously recognized. One new species in this group is described from Cameroon as Ceratocystis cerberus, while C. paradoxa sensu stricto (s. str.) and four other species are redefined. Lectotypes are designated for C. ethacetica and Endoconidium fragrans (synonym of C. ethacetica), w...
ABSTRACT Kirramyces stem canker, caused by species of Raederiella (previously Coniothyrium) is on... more ABSTRACT Kirramyces stem canker, caused by species of Raederiella (previously Coniothyrium) is one of the most important eucalypt stem diseases in the southern hemisphere. During a disease survey conducted in Zimbabwe, symptoms of the disease, characterised by discrete dark brown sunken lesions, kino exudation and pockets in the wood, were observed in four sites on E. grandis, E. camaldulensis, E. grandis-X-camaldulensis hybrid clone and E. propingua. The ITS region, exons 3 through 6 of the β-tubulin gene and the intron of the translation elongation factor 1-α gene were sequenced to identify the causal pathogen. Representative isolates from Zimbabwe were compared with authenticated isolates of T. zuluensis and T. gauchensis. Sequence comparisons identified the pathogens as T. gauchensis. This study is the first to confirm the presence of Kirramyces stem canker on eucalypts in Zimbabwe. Furthermore, it is the first to report T. gauchensis in Southern Africa.
A survey of diseases of exotic trees in plantations was undertaken in southern and southwestern E... more A survey of diseases of exotic trees in plantations was undertaken in southern and southwestern Ethiopia during 2000 and 2001. Our aim was to ascertain the occurrence and distribution of diseases of major plantation species and to provide a basis for further research. Root, stem and leaf samples were collected from both plantations and trees growing near farms and homesteads in and around Wondo Genet, Munessa Shashemene, Jima, Bedele, Mizan and Menagesha. Armillaria root rot was the most common disease, associated mainly with Pinus patula , but also found on Acacia abyssinica, Cordia alliodoral/ig and Cedrela odorata . Stem cankers associated with ligBotryosphaerial/ig species were common on Eucalyptus globulus, E. salignal/ig and E. citriodora . Stem canker disease associated with a ligConiothyriuml/ig species was commonly observed on E. camaldulensis . Leaf blotch associated with ligMycosphaerellal/ig species was common on E. globulusl/ig in most areas where this species is plante...
Little is known regarding the fungi, especially fungal pathogens, associated with mangroves in Af... more Little is known regarding the fungi, especially fungal pathogens, associated with mangroves in Africa. This includes fungi in the Botryosphaeriaceae that comprise numerous opportunistic, stress-associated pathogens often associated with trees affected by environmental and anthropogenically generated stresses, such as those affecting mangroves. We investigated the occurrence of endophytic Botryosphaeriaceae along the entire distribution of mangroves in South Africa. Asymptomatic branches were collected from ten localities and six mangrove species. Isolates resembling species of Botryosphaeriaceae were identified based on multi-gene sequence data of the internal transcribed spacer regions (ITS), including the 5.8S nrRNA, the beta-tubulin (tub2), partial translation elongation factor 1-alpha (tef1-α), and DNA-directed RNA polymerase II second largest subunit (rpb2) gene regions. Inoculation trials were conducted on healthy branches of Avicennia marina and Bruguiera gymnorrhiza to evalu...
Mangrove trees are continuously under stress due to environmental and/or anthropogenic pressures,... more Mangrove trees are continuously under stress due to environmental and/or anthropogenic pressures, which expose them to attack by pathogens, compromising their survival. Ophiostomatoid fungi cause sap stain and diseases of a wide spectrum of tree species globally. These fungi infect trees through natural, insect, animal and/or human made wounds. During routine surveys of mangrove trees in South Africa, wounds on branches and stems of Avicennia marina were regularly monitored for the presence of ophiostomatoid fungi at ten study sites in the country. The stems of four mangrove species, A. marina, Bruguiera gymnorrhiza, Rhizophora mucronata and Barringtonia racemosa were also wounded and evaluated for the appearance of these fungi. Ophiostomatoid fungi were obtained from the mangrove associate B. racemosa, but not from any of the true mangroves. Analyses of DNA sequence data for the internal transcribed spacer, β-tubulin, calmodulin and translation elongation factor gene regions reveal...
Armillaria root-rot is one of the most serious root diseases of perennial tree crops in tropical ... more Armillaria root-rot is one of the most serious root diseases of perennial tree crops in tropical Africa. The disease was first reported on cacao in Ghana during 1927. It was initially referred to as 'collar crack' due to typical longitudinal cracks that are formed in the bark at the tree collar, as a result of mechanical pressure from fungal fans colonizing the cambium. These fungal fans are typical of species in the genus Armillaria. The pathogen associated with the disease was identified as A. mellea (Valh Ex. Fr.). However, A. mellea is a taxonomic complex that currently includes a number of morphologically indistinguishable species, the true identity of the species causing root-rot on cacao in Africa is thus uncertain. More recent studies have shown that DNA sequence comparisons can effectively differentiate among Armillaria species from Africa with uniform morphologies. In this study we applied a molecular approach to characterize Armillaria isolates associated with roo...
During routine surveys for possible fungal pathogens in the rapidly expanding plantations of Euca... more During routine surveys for possible fungal pathogens in the rapidly expanding plantations of Eucalyptus and Cunninghamia lanceolata in China, numerous isolates of unknown species in the genus Ceratocystis (Microascales) were obtained from tree wounds. In this study we identified the Ceratocystis isolates from Eucalyptus and Cunninghamia in the GuangDong, GuangXi, FuJian and HaiNan Provinces of South China based on morphology and through comparisons of DNA sequence data for the ITS, partial β-tubulin and TEF-1α gene regions. Morphological and DNA sequence comparisons revealed two previously unknown species residing in the Indo-Pacific Clade. These are described here as Ceratocystis cercfabiensis sp. nov. and Ceratocystis collisensis sp. nov. Isolates of Ceratocystis cercfabiensis showed intragenomic variation in their ITS sequences and four strains were selected for cloning of the ITS gene region. Twelve ITS haplotypes were obtained from 17 clones selected for sequencing, differing i...
Identification of fungi and the International Code of Nomenclature underpinning this process, res... more Identification of fungi and the International Code of Nomenclature underpinning this process, rests strongly on the characterisation of morphological structures. Yet, the value of these characters to define species in many groups has become questionable or even superfluous. This has emerged as DNA-based techniques have increasingly revealed cryptic species and species complexes. This problem is vividly illustrated in the present study where 105 isolates of the Botryosphaeriales were recovered from both healthy and diseased woody tissues of native Acacia spp. in Namibia and South Africa. Thirteen phylogenetically distinct groups were identified based on Internal Transcribed Spacer (ITS) rDNA PCR-RFLP and translation elongation factor 1-α (TEF1-α) sequence data, two loci that are known to be reliable markers to distinguish species in the Botryosphaeriales. Four of these groups could be linked reliably to sequence data for formerly described species, including Botryosphaeria dothidea, ...
The Ceratocystis paradoxa complex accommodates a group of fungal pathogens that have become speci... more The Ceratocystis paradoxa complex accommodates a group of fungal pathogens that have become specialized to infect mostly monocotyledonous plants. Four species currently are recognized in this group, including C. paradoxa, which has a widespread distribution and broad host range. In this study, multigene phylogenetic analyses involving sequences of the ITS, β-tubulin and TEF-1α gene loci, in combination with phenotypic and mating studies, were used to characterize purported C. paradoxa isolates from Cameroon and to compare them with isolates from elsewhere, including protologs and type specimens of known species. We show that the C. paradoxa complex comprises substantially greater species diversity than previously recognized. One new species in this group is described from Cameroon as Ceratocystis cerberus, while C. paradoxa sensu stricto (s. str.) and four other species are redefined. Lectotypes are designated for C. ethacetica and Endoconidium fragrans (synonym of C. ethacetica), w...
ABSTRACT Kirramyces stem canker, caused by species of Raederiella (previously Coniothyrium) is on... more ABSTRACT Kirramyces stem canker, caused by species of Raederiella (previously Coniothyrium) is one of the most important eucalypt stem diseases in the southern hemisphere. During a disease survey conducted in Zimbabwe, symptoms of the disease, characterised by discrete dark brown sunken lesions, kino exudation and pockets in the wood, were observed in four sites on E. grandis, E. camaldulensis, E. grandis-X-camaldulensis hybrid clone and E. propingua. The ITS region, exons 3 through 6 of the β-tubulin gene and the intron of the translation elongation factor 1-α gene were sequenced to identify the causal pathogen. Representative isolates from Zimbabwe were compared with authenticated isolates of T. zuluensis and T. gauchensis. Sequence comparisons identified the pathogens as T. gauchensis. This study is the first to confirm the presence of Kirramyces stem canker on eucalypts in Zimbabwe. Furthermore, it is the first to report T. gauchensis in Southern Africa.
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