Search

A detailed site investigation of a eucalypt nursery suffering disease losses revealed the causal agent to be Phytophthora boodjera. The pathogen was detected in vegetation surrounding the nursery production area, including the lawn, under the production benches during the growing season, and, most importantly, from plant debris in used trays. However, it was not found in the container substrate, water supplies, or production equipment or on the workers themselves. The sterilization methods used by the nursery were shown to be ineffective, indicating that a more rigorous method was required. Boiling trays for 15 min or steaming at 65°C for 60 min eradicated P. boodjera. This pathogen was more pathogenic to the eucalypts tested in their early seedling stage than P. cinnamomi. Tracing of out-planting to revegetation sites showed that P. boodjera was able to spread into the environment. Dispersal via out-planting to native vegetation may affect seedling recruitment and drive long-term shifts in native plant species. Inadequate nursery hygiene increases the risk of an outbreak and can limit the success of biosecurity efforts as well as damage conservation efforts.

Globally, Phytophthora cinnamomi is listed as one of the 100 worst invasive alien species and active management is required to reduce impact and prevent spread in both horticulture and natural ecosystems. Conversely, there are regions thought to be suitable for the pathogen where no disease is observed. We developed a climex model for the global distribution of P. cinnamomi based on the pathogen's response to temperature and moisture and by incorporating extensive empirical evidence on the presence and absence of the pathogen. The climex model captured areas of climatic suitability where P. cinnamomi occurs that is congruent with all available records. The model was validated by the collection of soil samples from asymptomatic vegetation in areas projected to be suitable by the model for which there were few records. DNA was extracted, and the presence or absence of P. cinnamomi was determined by high-throughput sequencing (HTS). While not detected using traditional isolation methods, HTS detected P. cinnamomi at higher elevations in eastern Australia and central Tasmania as projected by the climex model. Further support for the climex model was obtained using the large data set from south-west Australia where the proportion of positive records in an area is related to the Ecoclimatic Index value for the same area. We provide for the first time a comprehensive global map of the current P. cinnamomi distribution, an improved climex model of the distribution, and a projection to 2080 of the distribution with predicted climate change. This information provides the basis for more detailed regional-scale modelling and supports risk assessment for governments to plan management of this important soil-borne plant pathogen., (© 2016 John Wiley & Sons Ltd.)

Phytophthora cinnamomi is one of the world's most invasive plant pathogens affecting ornamental plants, horticultural crops and natural ecosystems. Accurate diagnosis is very important to determine the presence or absence of this pathogen in diseased and asymptomatic plants. In previous studies, P. cinnamomi species-specific primers were designed and tested using various polymerase chain reaction (PCR) techniques including conventional PCR, nested PCR and quantitative real-time PCR. In all cases, the primers were stated to be highly specific and sensitive to P. cinnamomi. However, few of these studies tested their primers against closely related Phytophthora species (Phytophthora clade 7). In this study, we tested these purported P. cinnamomi-specific primer sets against 11 other species from clade 7 and determined their specificity; of the eight tested primer sets only three were specific to P. cinnamomi. This study demonstrated the importance of testing primers against closely related species within the same clade, and not just other species within the same genus. The findings of this study are relevant to all species-specific microbial diagnosis., (© FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

A non-papillate, heterothallic Phytophthora species first isolated in 2001 and subsequently from symptomatic roots, crowns and stems of 33 plant species in 25 unrelated botanical families from 13 countries is formally described here as a new species. Symptoms on various hosts included crown and stem rot, chlorosis, wilting, leaf blight, cankers and gumming. This species was isolated from Australia, Hungary, Israel, Italy, Japan, the Netherlands, Norway, South Africa, Spain, Taiwan, Turkey, the United Kingdom and United States in association with shrubs and herbaceous ornamentals grown mainly in greenhouses. The most prevalent hosts are English ivy (Hedera helix) and Cistus (Cistus salvifolius). The association of the species with acorn banksia (Banksia prionotes) plants in natural ecosystems in Australia, in affected vineyards (Vitis vinifera) in South Africa and almond (Prunus dulcis) trees in Spain and Turkey in addition to infection of shrubs and herbaceous ornamentals in a broad range of unrelated families are a sign of a wide ecological adaptation of the species and its potential threat to agricultural and natural ecosystems. The morphology of the persistent non-papillate ellipsoid sporangia, unique toruloid lobate hyphal swellings and amphigynous antheridia does not match any of the described species. Phylogenetic analysis based on sequences of the ITS rDNA, EF-1α, and β-tub supported that this organism is a hitherto unknown species. It is closely related to species in ITS clade 7b with the most closely related species being P. sojae. The name Phytophthora niederhauserii has been used in previous studies without the formal description of the holotype. This name is validated in this manuscript with the formal description of Phytophthora niederhauserii Z.G. Abad et J.A. Abad, sp. nov. The name is coined to honor Dr John S. Niederhauser, a notable plant pathologist and the 1990 World Food Prize laureate., (© 2014 by The Mycological Society of America.)

Eucalyptus gomphocephala (tuart) is a tree native to the southwest coast of Western Australia, where, in some areas, there is a significant decline in the health of tuart. Botryosphaeriaceous taxa have been isolated as endophytes and canker pathogens from numerous hosts in many parts of the world and have been implicated in the decline of E. gomphocephala. In the present study, endophytic fungi were isolated from a wide variety of native woody plant species (Acacia cochlearis, A. rostellifera, Allocasuarina fraseriana, Agonis flexuosa, Banksia grandis, E. gomphocephala, E. marginata and Santalum acuminatum), at two locations in native E. gomphocephala woodland; a site in decline at Yalgorup National Park and a healthy site at Woodman Point Regional Park. Of the 226 isolates obtained, 154 were botryosphaeriaceous taxa, 80% of which were found to be Neofusicoccum australe, isolated from all hosts at both collection sites. Four new species are described, Dothiorella moneti, Dothiorella santali, Neofusicoccum pennatisporum, and a species belonging to a genus only recently included in the Botryosphaeriaceae, Aplosporella yalgorensis. The other species isolated were Botryosphaeria dothidea on the new hosts A. rostellifera, A. cochlearis and E. marginata and Dichomera eucalypti, on the new host E. marginata. None of the new species formed lesions on excised stems of their host species, E. gomphocephala, or a common plantation species, E. globulus. However, Neofusicoccum australe formed lesions on excised stems of E. globulus and E. gomphocephala.

In this study seven new species of the Botryosphaeriaceae are described from baobab (Adansonia gibbosa) and surrounding endemic tree species growing in the Kimberley region of northwestern Australia. Members of the Botryosphaeriaceae were predominantly endophytes isolated from apparently healthy sapwood and bark of endemic trees; others were isolated from dying branches. Phylogenetic analyses of ITS and EF1-alpha sequence data revealed seven new species: Dothiorella longicollis, Fusicoccum ramosum, Lasiodiplodia margaritacea, Neoscytalidium novaehollandiae, Pseudofusicoccum adansoniae, P. ardesiacum and P. kimberleyense.

A severe canker disease has been causing decline and death of Corymbia calophylla in the southwest of Western Australia (WA) for some years, but the causal agent has never been investigated. However, there have been historical reports dating back to the 1920s of a canker disease of amenity planted C. ficifolia caused by 'Sporotrichum destructor', though the description and Latin diagnosis were never published. It has been suggested that there may be links between this species and the genus Quambalaria, a group containing leaf and shoot pathogens of species of Eucalyptus and Corymbia. The aim of this study was to investigate the identity of the pathogen historically attributed to canker disease of C. ficifolia, determine whether this pathogen is responsible for the current epidemic of C. calophylla canker, and whether it is synonymous with Quambalaria. Surveys examined the range of Quambalaria spp. on Corymbia spp. endemic to southwest WA. Their phylogenetic relationship to Q. cyanescens, Q. eucalypti, and Q. pitereka was examined using rLSU and ITS sequence data. Morphological characters were also compared. Sequences confirmed that Q. cyanescens and Q. pitereka are present in southwest WA, with the latter associated with leaf and shoot disease. A third group isolated from cankers represent a new species of Quambalaria. Comparisons of disease symptoms and conidiogenesis indicate this species is synonymous with 'S. destructor'. The species is formally described here as Q. coyrecup sp. nov.

A recent study to determine the cause of collar and root rot disease outbreaks of cold tolerant Eucalyptus species in South Africa resulted in the isolation of two putative new Phytophthora species. Based on phylogenetic comparisons using the ITS and beta-tubulin gene regions, these species were shown to be distinct from known species. These differences were also supported by robust morphological characteristics. The names, Phytophthora frigida sp. nov. and Phytophthora alticola sp. nov. are thus provided for these taxa, which are phylogenetically closely related to species within the ITS clade 2 (P. citricola, P. tropicali and P.multivesiculata) and 4 (P. arecae and P. megakarya), respectively. Phytophthora frigida is heterothallic, and produces stellate to rosaceous growth patterns on growth medium, corraloid hyphae, sporangia with a variety of distorted shapes and has the ability to grow at low temperatures. Phytophthora alticola is homothallic and has a slower growth rate in culture. Both P. frigida and P. alticola are pathogenic to Eucalyptus dunnii. In pathogenicity tests, they were, however, less pathogenic than P. cinnamomi, which is a well-known pathogen of Eucalyptus in South Africa.

Species of Phaeophleospora are anamorphs of Mycosphaerella and they include some of the most serious foliar pathogens of Eucalyptus spp. grown in plantations worldwide. Pathogens assigned to this genus and occurring on Eucalyptus spp. were previously treated in Kirramyces and they are also phylogenetically closely related to other anamorphs of Mycosphaerella residing in the genus Colletogloeopsis. The primary aim of this study was to consider the appropriate taxonomic placement of these species. To achieve this goal, morphological characteristics and DNA sequence data from the ITS and translation EF1-alpha gene regions were used to compare the type species P. eugeniae, Phaeophleospora spp. and Colletogloeopsis spp. occurring on eucalypts, using ex-type cultures and herbarium specimens. Phylogenetic data and morphological comparisons supported the separation of P. eugeniae from Phaeophleospora species occurring on eucalypts. The name Phaeophleospora is retained for P. eugeniae and the name Kirramyces is resurrected for the species occurring on eucalypts (genera Eucalyptus, Corymbia, and Angophora). Sequence data from the type specimens of two previously described species of Kirramyces, K. lilianiae and K. delegatensis, show they reside in a clade with other Kirramyces spp. Morphological and DNA sequence comparisons also showed that there is considerable overlap between species of Phaeophleospora and Colletogloeopsis from eucalypts. Based on these findings, Colletogloeopsis is reduced to synonymy with the older Kirramyces and the description of Kirramyces is emended to include species with aseptate, as well as multiseptate, conidia produced in acervuli or pycnidia. Two new species of Kirramyces, K. angophorae and K. corymbiae, are also described.

The majority of Eucalyptus species are native to Australia, but worldwide there are over 3 million ha of exotic plantations, especially in the tropics and subtropics. Of the numerous known leaf diseases, three species of Phaeophleospora can cause severe defoliation of young Eucalyptus; Phaeophleospora destructans, Phaeophleospora eucalypti and Phaeophleospora epicoccoides. Phaeophleospora destructans has a major impact on seedling survival in Asia and has not, as yet, been found in Australia where it is considered a serious threat to the biosecurity of native eucalypts. It can be difficult to distinguish Phaeophleospora species based on symptoms and micromorphology and an unequivocal diagnostic tool for quarantine purposes would be useful. In this study, a multiple gene genealogy of these Phaeophleospora species and designed specific primers has been constructed to detect their presence from leaf samples. The phylogenetic position of these Phaeophleospora species within Mycosphaerella was established. They are closely related to each other and to other important Eucalyptus pathogens, Mycosphaerella nubilosa, Mycosphaerella cryptica and Colletogloeopsis zuluensis. The specific primers developed can now be used for diagnostic and screening purposes within Australia.

Botryosphaeria rhodina (anamorph Lasiodiplodia theobromae) is a common endophyte and opportunistic pathogen on more than 500 tree species in the tropics and subtropics. During routine disease surveys of plantations in Australia and Venezuela several isolates differing from L. theobromae were identified and subsequently characterized based upon morphology and ITS and EF1-alpha nucleotide sequences. These isolates grouped into three strongly supported clades related to but different from the known taxa, B. rhodina and L. gonubiensis, These have been described here as three new species L. venezuelensis sp. nov., L. crassispora sp. nov. and L. rubropurpurea sp. nov. The three could be distinguished easily from each other and the two described species of Lasiodiplodia, thus confirming phylogenetic separations. Furthermore all five Lasiodiplodia spp. now recognized separated from Diplodia spp. and Dothiorella spp. with 100% bootstrap support.