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1
Moore, Nicole, Sarah Barrett, Kay Howard, Michael D. Craig, Barbara Bowen, Bryan Shearer e Giles Hardy. "Time since fire and average fire interval are the best predictors of Phytophthora cinnamomi activity in heathlands of south-western Australia". Australian Journal of Botany 62, n. 7 (2014): 587. http://dx.doi.org/10.1071/bt14188.
Testo completoAbstract (sommario):
Fires are features of ecological communities in much of Australia; however, very little is still known about the potential impact of fire on plant diseases in the natural environment. Phytophthora cinnamomi is an introduced soil-borne plant pathogen with a wide host range, affecting a large proportion of native plant species in Australia and other regions of the world, but its interaction with fire is poorly understood. An investigation of the effects of fire on P. cinnamomi activity was undertaken in the Stirling Range National Park of south-western Australia, where fire is used as a management tool to reduce the negative impact of wildfires and more than 60% of the park is infested with, and 48% of woody plant species are known to be susceptible to, P. cinnamomi. At eight sites confirmed to be infested with P. cinnamomi, the proportion of dead and dying susceptible species was used as a proxy for P. cinnamomi activity. Subset modelling was used to determine the interactive effects of latest fire interval, average fire interval, soil water-holding capacity and pH on P. cinnamomi activity. It was found that the latest and average fire interval were the variables that best explained the variation in the percentage of dead and dying susceptible species among sites, indicating that fire in P. cinnamomi-infested communities has the potential to increase both the severity and extent of disease in native plant communities.
2
Shearer, BL, e M. Dillon. "Impact and Disease Centre Characteristics of Phytophthora cinnamomi Infestations of Banksia Woodlands on the Swan Coastal Plain, Western Australia". Australian Journal of Botany 44, n. 1 (1996): 79. http://dx.doi.org/10.1071/bt9960079.
Testo completoAbstract (sommario):
Phytophthora cinnamomi Rands was isolated from either dead plants or soil at 46 disease centres in Banksia woodland at national parks and reserves on the Swan Coastal Plain. Phytophthora cryptogea Pethybridge & Lafferty was also isolated from roots of dead Acacia pulchella R.Br. in one disease centre infected with P. cinnamomi. Dead plants were infected with Armillaria luteobubalina Watling & Kile in four disease centres on the Spearwood Dune System, and these centres were excluded from further analysis. Phytophthora cinnamomi diseased areas ranged from 0.01 to 30 ha in size (mean 1.6 ± s.e. 0.7 ha). The total area infested for the 46 disease centres was 71.5 ha. Impact of P. cinnamomi was high in 17% of disease centres and low in 11% of disease centres. Age of plant death was a mixture of old and recent in 85% of disease centres. Mainly old deaths occurred in only 4% of disease centres. The proportion of species dying in infested areas varied between 10-64% (mean 28 ± s.e. 2%) and was positively correlated with impact type. It was found that infestation decreased species number; on average, there were seven fewer species in infested compared to non-infested areas. Four plant species associated with moist sandy sites tended to occur more frequently in centres of high impact than by chance alone. Occurrence of P. cinnamomi was related to soil association with soils of 60% of the disease centres belonging to the Bassendean or Southern River associations of the Bassendean Dune System. Sixteen percent of disease centres occurred in the Cannington, Guildford and Serpentine River associations of the Pinjarra Plain. No disease centres of P. cinnamomi were found on soils of the Speanvood and Quindalup Dune Systems. A water table was found within 3 m of the soil surface in 48% of the centres. Disturbance was associated with all disease centres. Firebreaks were associated with 72% of disease centres. Banksia woodland remnants on the Bassendean Dune System and the Pinjarra Plain are highly vulnerable to infection by P. cinnamomi and their conservation requires control of existing infestatinns and protection from introduction af the pathogen.
3
Wilson, Barbara A., Katherine Zdunic, Janine Kinloch e Graeme Behn. "Use of remote sensing to map occurrence and spread of Phytophthora cinnamomi in Banksia woodlands on the Gnangara Groundwater System, Western Australia". Australian Journal of Botany 60, n. 6 (2012): 495. http://dx.doi.org/10.1071/bt11305.
Testo completoAbstract (sommario):
The soilborne plant pathogen Phytophthora cinnamomi is listed as one of the world’s 100 worst invasive alien species by the International Union for Conservation of Nature (IUCN). The impacts on native flora and fauna habitats have been identified as a key threatening process in Australia. Identifying and mapping diseased vegetation and the rate of spread of the disease is required for management; however, this is often difficult and costly. This study investigated the ability of using a time series of orthophotos (1953–2008) in combination with Landsat satellite imagery, including trend analysis, and GIS to identify the presence of vegetation impacted by P. cinnamomi at four sites in Banksia woodlands in Western Australia. Further, the historical extent and rate of spread of P. cinnamomi was assessed at one site between 1953 and 2008. Our assessment identified that three of the four sites were affected by P. cinnamomi, results that are consistent with on-ground surveys. Investigation of disease progression at one site found a large increase in the area impacted between 1974 and 1988 and the rate of spread was highest between 1953 and 1963 (1.286 m year−1) and lowest between 1997 and 2008 (0.526 m year−1). The techniques presented provide a cost-effective tool to monitor broad-scale vegetation dynamics over time for management of this plant pathogen.
4
Jung, T., e G. Dobler. "First Report of Littleleaf Disease Caused by Phytophthora cinnamomi on Pinus occidentalis in the Dominican Republic". Plant Disease 86, n. 11 (novembre 2002): 1275. http://dx.doi.org/10.1094/pdis.2002.86.11.1275c.
Testo completoAbstract (sommario):
Pinus occidentalis Sw. is an endemic species of the Caribbean island of Hispaniola (Dominican Republic and Haiti). It shows an extreme ecological plasticity and grows on a wide range of soil types from 0 to 3,175 m in elevation with annual mean temperatures ranging from 6 to 25°C and annual precipitation of 800 to 2,300 mm. P. occidentalis is a major component of forests above 800 m in elevation and forms pure climax forests above 2,000 m (4). For more than 10 years, stands of P. occidentalis in the Sierra (Cordillera Central) growing on a wide range of site conditions have suffered from a serious widespread disease. Symptoms include yellowing and dwarfing of needles, a progressive defoliation and dieback of the crown, and finally, death of weakened trees often caused by attacks by secondary bark beetles. Mature stands are mainly affected, but the disease is also present in plantations and natural regeneration that is older than 10 years. Disease spread is rapid, and occurs mainly along roads and from diseased trees downslope following the path of water runoff. Initially, Leptographium serpens was isolated from necrotic roots and was thought to be the causal agent (1). However, the symptoms of the disease more closely resemble those of littleleaf disease of P. echinata and P. taeda in the southeastern United States, which is caused by the aggressive fine-root pathogen Phytophthora cinnamomi Rands (3). Moreover, spread and dynamics of the disease are similar to the diebacks of Chamaecyparis lawsoniana in Oregon and Eucalyptus spp. in western Australia, which are caused by the introduced soilborne pathogens Phytophthora lateralis and Phytophthora cinnamomi, respectively. Soil samples containing the rhizosphere and fine roots of diseased P. occidentalis trees were collected in February 2002 at five sites near Celestina and Los Montones (Dominican Republic) and transported to the Bavarian State Institute of Forestry. The pathogen was baited from the soil by floating 3- to 7-dayold leaves of Quercus robur seedlings over flooded soil and placing the leaves on selective PARPNH agar (2). Phytophthora cinnamomi was isolated from the soil of all five sites. Crossing with A1 and A2 tester strains of Phytophthora cinnamomi confirmed that all isolates belong to the A2 mating type. In cross sections of necrotic fine roots, characteristic structures of Phytophthora cinnamomi such as nonseptate hyphae and chlamydospores could be observed. Our results indicate that the disease of P. occidentalis is caused by the introduced pathogen Phytophthora cinnamomi. Because of the ecological and economical importance of P. occidentalis, the disease poses a major threat to forestry in the Dominican Republic. Future research should include the mapping of the disease, pathogenicity tests on P. occidentalis and alternative pine species, in particular P. caribaea, screening for resistance in the field, and testing of systemic fungicides such as potassium phosphonate, which is known to be effective against Phytophthora cinnamomi. References: (1) G. Dobler. Manejo y Tablas de Rendimiento de Pinus occidentalis. Plan Sierra, San José de las Matas, Dominican Republic, 1999. (2) T. Jung et al. Plant Pathol. 49:706, 2000. (3) S. W. Oak and F. H. Tainter. How to identify and control littleleaf disease. Protection Rep. R8-PR12, USDA Forest Service Southern Region, Atlanta, Georgia, 1988. (4) L. Sprich. Allg. Forst. Jagdztg. 168:67, 1997.
5
McDougall, K. L., G. E. St J. Hardy e R. J. Hobbs. "Additions to the host range of Phytophthora cinnamomi in the jarrah (Eucalyptus marginata) forest of Western Australia". Australian Journal of Botany 49, n. 2 (2001): 193. http://dx.doi.org/10.1071/bt99028.
Testo completoAbstract (sommario):
Pathogenicity tests with Phytophthora cinnamomi were conducted on 25 perennial species from the jarrah (Eucalyptus marginata) forest of Western Australia. Most species tested had been found in a separate study to be scarce on sites affected by Phytophthora cinnamomi but frequently found in unaffected vegetation. Some species that were known to be field-tolerant of P. cinnamomi and some that were highly susceptible to infection were included in the study for comparison. Phytophthora cinnamomi was recorded from 13 of 17 species not previously known to be susceptible. Phytophthora cinnamomi was subsequently isolated from dead plants of two of these 13 species in the field. The interpretation of results from the glasshouse trials was difficult for some species because of inconsistent patterns of death and P. cinnamomi isolation in the glasshouse trials. Phytophthora cinnamomi probably causes decline in wild populations of Stylidium amoenum, based on the ease of field and glasshouse isolation of P. cinnamomi and the scarcity of this forb on dieback sites. It may also contribute to decline in populations of Boronia fastigiata, Hybanthus floribundus, Labichea punctata, Scaevola calliptera and Stylidium junceum, although further field sampling is required to confirm this.
6
Hart, R. M., D. Keast e G. Smythe. "Metabolic stability of Phytophthora cinnamomi Rands in Western Australia". Canadian Journal of Microbiology 32, n. 10 (1 ottobre 1986): 820–22. http://dx.doi.org/10.1139/m86-150.
Testo completoAbstract (sommario):
Ten isolates of Phytophthora cinnamomi Rands from Western Australia were tested for metabolic variation using a commercial miniaturized biochemical system developed for bacteriology. The isolates included the two mating strains, and had been maintained in the laboratory for various times. The isolates were tested before and after repeated passaging on solid media. Statistical analysis of the biochemical results showed no major differences between the isolates, and for the most part they appear to be stable in cultivation. However, there were small passage effects on some of the media, particularly with glucose utilization.
7
McDougall, K. L., R. J. Hobbs e G. E. St J. Hardy. "Distribution of understorey species in forest affected by Phytophthora cinnamomi in south-western Western Australia". Australian Journal of Botany 53, n. 8 (2005): 813. http://dx.doi.org/10.1071/bt04203.
Testo completoAbstract (sommario):
The introduced soil-borne pathogen Phytophthora cinnamomi Rands infects and kills a large number of species in the jarrah (Eucalyptus marginata Donn. ex Smith) forest of Western Australia, causing great floristic and structural change. Many of the floristic changes can be explained simply by the known susceptibility of species to infection. Some common species, however, are rarely found at infested sites but are thought to be resistant to infection. It has been postulated that such species may be affected by the change in habitat caused by the death of trees, and not by P. cinnamomi directly. If this were the case, such species should cluster around surviving trees at infested sites. The occurrence of a susceptible species in the vicinity of trees surviving at infested sites has also been reported. To investigate the spatial relationship between trees and understorey species, the positions of trees and selected perennial understorey species were mapped at two sites in jarrah forest long-affected by P. cinnamomi. Random sets of plants and trees were generated and used in simulations to test whether understorey species grew closer to trees than expected. Many understorey species, both resistant and susceptible to infection by P. cinnamomi, were found to grow closer than expected to trees currently growing at the sites and closer to the trees that would have been present at the time of infestation. This suggests that not only do these trees enable some resistant species to persist at infested sites but that they also offer protection to some susceptible species against damage by P. cinnamomi. The proximity of many understorey species to trees that are likely to have appeared at the study sites since the first infestation indicates that the maintenance and enhancement of tree cover at infested sites in the jarrah forest may limit the damage caused by P. cinnamomi and assist in the protection of biodiversity.
8
Shearer, B. L., C. E. Crane e A. Cochrane. "Quantification of the susceptibility of the native flora of the South-West Botanical Province, Western Australia, to Phytophthora cinnamomi". Australian Journal of Botany 52, n. 4 (2004): 435. http://dx.doi.org/10.1071/bt03131.
Testo completoAbstract (sommario):
This study compares, for the first time, variation in estimates of susceptibility of native flora to Phytophthora cinnamomi Rands among four databases and proposes an estimate of the proportion of the flora of the South-West Botanical Province of Western Australia that is susceptible to the pathogen. Estimates of the susceptibility of south-western native flora to P. cinnamomi infection were obtained from databases for Banksia woodland of the Swan Coastal Plain, jarrah (Eucalyptus marginata Donn. ex Smith) forest, the Stirling Range National Park and Rare and Threatened Flora of Western Australia. For the woodland, forest and national park databases, hosts were naturally infected in uncontrolled diverse natural environments. In contrast, threatened flora were artificially inoculated in a shadehouse environment. Considerable variation occurred within taxonomic units, making occurrence within family and genus poor predictors of species susceptibility. Identification of intra-specific resistance suggests that P. cinnamomi could be having a strong selection pressure on some threatened flora at infested sites and the populations could shift to more resistant types. Similar estimates of the proportion of species susceptible to P. cinnamomi among the databases from the wide range of environments suggests that a realistic estimate of species susceptibility to P. cinnamomi infection in the south-western region has been obtained. The mean of 40% susceptible and 14% highly susceptible equates to 2284 and 800 species of the 5710 described plant species in the South-West Botanical Province susceptible and highly susceptible to P. cinnamomi, respectively. Such estimates are important for determining the cost of disease to conservation values and for prioritising disease importance and research priorities. P. cinnamomi in south-western Australia is an unparalleled example of an introduced pathogen with a wide host range causing immense irreversible damage to unique, diverse but mainly susceptible plant communities.
9
Boersma, J. G., D. E. L. Cooke e K. Sivasithamparam. "A survey of wildflower farms in the south-west of Western Australia for Phytophthora spp. associated with root rots". Australian Journal of Experimental Agriculture 40, n. 7 (2000): 1011. http://dx.doi.org/10.1071/ea00013.
Testo completoAbstract (sommario):
A survey of wildflower farms in the south west of Western Australia, was conducted during spring of 1997 and autumn 1998 to determine the prevalence of Phytophthora infestations. Thirty-seven randomly selected farms ranging in size from 0.5 to =30 ha were visited. The main crop plants grown included species of Banksia, Boronia, Chamelaucium, Conospermum, Eucalyptus, Protea, and Leucadendron. Eighteen sites were found to have infestations of Phytophthora. Of these, 14 sites had P. cinnamomi, and 2 sites had P. cryptogea. P. cactorum, P. citricola and P. nicotianae were each found at only single locations. One site was found to have both P. cinnamomi and P. cryptogea. Species of Phytophthora were identified morphologically, isozymically, and using species-specific PCR primers. Not every species could be identified by all 3 methods. There was no apparent association between geographical location and the occurrence of Phytophthora spp.
10
Tynan, K. M., C. J. Wilkinson, J. M. Holmes, B. Dell, I. J. Colquhoun, J. A. McComb e G. E. St J. Hardy. "The long-term ability of phosphite to control Phytophthora cinnamomi in two native plant communities of Western Australia". Australian Journal of Botany 49, n. 6 (2001): 761. http://dx.doi.org/10.1071/bt00062.
Testo completoAbstract (sommario):
This study examined the ability of foliar applications of the fungicide phosphite to contain colonisation of Phytophthora cinnamomi in a range of plant species growing in natural plant communities in the northern sandplain and jarrah (Eucalyptus marginata) forest of south-western Australia. Wound inoculation of plant stems with P. cinnamomi was used to determine the efficacy of phosphite over time after application. Colonisation by P. cinnamomi was reduced for 5–24 months after phosphite was applied, depending on the concentration of phosphite used, plant species treated and the time of phosphite application. Plant species within and between plant communities varied considerably in their ability to take up and retain phosphite in inoculated stems and in the in planta concentrations of phosphite required to contain P. cinnamomi. As spray application rates of phosphite increased from 5 to 20 g L–1, stem tissue concentrations increased, as did the ability of a plant species to contain P. cinnamomi. However, at application rates of phosphite above 5 g L–1 phytotoxicity symptoms were obvious in most species, with some plants being killed. So, despite 10 and 20 g L–1 of phosphite being more effective and persistent in controlling P. cinnamomi, these rates are not recommended for application to the plant species studied. The results of this study indicate that foliar application of phosphite has considerable potential in reducing the impact of P. cinnamomi in native plant communities in the short-term. However, in order to maintain adequate control, phosphite should be sprayed every 6–12 months, depending on the species and/or plant community.
11
D'Souza, Nola K., Ian J. Colquhoun, Bryan L. Shearer e Giles E. St J. Hardy. "The potential of five Western Australian native Acacia species for biological control of Phytophthora cinnamomi". Australian Journal of Botany 52, n. 2 (2004): 267. http://dx.doi.org/10.1071/bt03089.
Testo completoAbstract (sommario):
Five Acacia species native to Western Australia were assessed for their potential to protect the highly susceptible species Banksia grandis Wield from infection by the plant pathogen Phytophthora cinnamomi Rands. In a rehabilitated bauxite pit at Jarrahdale 55 km south-east of Perth and in a glasshouse trial, B. grandis planted either alone or with A. pulchella R.Br., A. urophylla Benth., A. extensa Lindl., A. lateriticola Maslin or A. drummondii Lindl., was soil inoculated with P. cinnamomi. It could only be shown that A. pulchella significantly protected B. grandis from P. cinnamomi infection in the rehabilitated bauxite pit trial up to 1 year after inoculation. This confirms the potential of this species for biological control of the pathogen in infested plant communities. The observed protection was not the result of a decrease in soil temperature or moisture. Protection was not emulated in a glasshouse trial where optimum environmental conditions favoured P. cinnamomi. Despite a delay in infection of B. grandis planted with Acacia spp., none of the five species definitively protected B. grandis from P. cinnamomi. However, in the glasshouse trial, A. pulchella, A. extensa, A. lateriticola and A. drummondii did significantly reduce the soil inoculum of P. cinnamomi, indicating a possible biological control effect on the pathogen. The mechanisms of biological control are discussed and the implications for management of rehabilitated bauxite mined areas and forests severely affected by P. cinnamomi are considered.
12
Shearer, BL, e M. Dillon. "Susceptibility of Plant Species in Banksia Woodlands on the Swan Coastal Plain, Western Australia, to Infection by Phytophthora cinnamomi". Australian Journal of Botany 44, n. 4 (1996): 433. http://dx.doi.org/10.1071/bt9960433.
Testo completoAbstract (sommario):
Estimates of the susceptibility of plant species in Banksia woodland to Phytophthora cinnamomi Rands were obtained by determining the incidence of plant death and frequency of isolation of the pathogen, among species occurring in 46 disease centres on the Swan Coastal Plain south of Perth, Western Australia. In the disease centres, dicotyledons outnumbered monocotyledons. About half of all species occurring in the disease centres were from four families of dicotyledons, with the largest number of species from the Myrtaceae, Proteaceae and Papilionaceae. The greatest number of species of monocotyledons were from the Anthericaceae and Cyperaceae. No deaths were recorded for 47% of species found in three or more disease centres. These species were mainly from the Cyperaceae, Haemodoraceae, Myrtaceae and Papilionaceae. The species that tended to die frequently in disease centres were mainly from the Papilionaceae, Proteaceae, Epacridaceae, Xanthorrhoeaceae and the Zamiaceae. Phytophthora cinnamomi was isolated from 26 of the 95 species occurring in three or more disease centres. For most species, the frequency of isolation of P. cinnamomi from recently dead plants was much less than the frequency of dead plants sampled. Isolation from plants was less frequent than from adjacent soil. The pathogen was isolated from recently dead plants or soil mainly for species of the Proteaceae, Myrtaceae, Papilionaceae, Dasypogonaceae, Iridaceae and Xanthorrhoeaceae. Cross-tabulation of species by incidence of plant death and isolation of P. cinnamomi from plant and soil, provided the opportunity to classify the response of plant species to infection by P. cinnamomi.
13
McDougall, K. L., R. J. Hobbs e G. E. St Hardy. "Vegetation of Phytophthora cinnamomi-infested and adjoining uninfested sites in the northern jarrah (Eucalyptus marginata) forest of Western Australia". Australian Journal of Botany 50, n. 3 (2002): 277. http://dx.doi.org/10.1071/bt01096.
Testo completoAbstract (sommario):
The vegetation of seven sites in the northern jarrah forest of Western Australia infested with Phytophthora cinnamomi was recorded and compared with adjoining vegetation. The number of species per quadrat was found to be the same in vegetation affected by P. cinnamomi as in healthy vegetation, although there were more species overall in affected vegetation. Vegetation of uninfested sites had a higher cover and more species per quadrat of trees and shrubs and lower cover and fewer species per quadrat of annual plants than vegetation of infested sites. Although many species that are known to be highly susceptible to infection by P. cinnamomi were rare at infested sites, only two (Banksia grandis and Tetratheca hirsuta) were absent from all of the 50-year-old infested parts of sites. Several species that are known to be highly susceptible to infection by P. cinnamomi were as common at infested as at healthy sites. The presence of such species at infested sites and the capacity of P. cinnamomi to infect species it does not kill suggest that this pathogen will persist and continue to influence future vegetation in the jarrah forest.
14
El-Tarabily, Khaled A., Melissa L. Sykes, Ipek D. Kurtböke, Giles E. St J. Hardy, Aneli M. Barbosa e Robert F. H. Dekker. "Synergistic effects of a cellulase-producing Micromonospora carbonacea and an antibiotic-producing Streptomyces violascens on the suppression of Phytophthora cinnamomi root rot of Banksia grandis". Canadian Journal of Botany 74, n. 4 (1 aprile 1996): 618–24. http://dx.doi.org/10.1139/b96-078.
Testo completoAbstract (sommario):
Three polyvalent Streptomyces phages were used to isolate four Micromonospora species (M. carbonacea, M. chalcea, M. purpureochromogenes, and M. inositola) from mine-site rhizosphere soils in Western Australia. Streptomyces violascens was isolated using selective isolation techniques from the same soils. The Micromonspora spp. were examined for their ability to produce cellulases. Micromonospora carbonacea, M. chalcea, and M. purpureochromogenes, which were found to produce the enzyme, caused lysis of Phytophthora cinnamomi hyphae. Glasshouse trials showed that the use of the cellulase-producing M. carbonacea isolate, in conjunction with the antibiotic-producing S. violascens isolate, had a synergistic effect on the suppression of the Phytophthora root rot and in promoting growth of Banksia grandis. The importance of using a number of antagonists with different antagonistic abilities to control plant pathogenic fungi is discussed. Keywords: biological control, Micromonospora carbonacea, Streptomyces violascens, cellulases, Phytophthora cinnamomi.
15
Shearer, B. L., C. E. Crane, S. Barrett e A. Cochrane. "Phytophthora cinnamomi invasion, a major threatening process to conservation of flora diversity in the South-west Botanical Province of Western Australia". Australian Journal of Botany 55, n. 3 (2007): 225. http://dx.doi.org/10.1071/bt06019.
Testo completoAbstract (sommario):
The invasive soilborne plant pathogen Phytophthora cinnamomi Rands is a major threatening process in the South-west Botanical Province of Western Australia, an internationally recognised biodiversity hotspot. Comparatively recent introduction of P. cinnamomi into native plant communities of the South-west Botanical Province of Western Australia since the early 1900s has caused great irreversible damage and altered successional change to a wide range of unique, diverse and mainly susceptible plant communities. The cost of P. cinnamomi infestation to community values is illustrated by examination of direct (mortality curves, changes in vegetation cover) and indirect impacts on biodiversity and ecosystem dynamics, the proportion of Threatened Ecological Communities infested, Declared Rare Flora either directly or indirectly threatened by infestation and estimates of the proportion of the native flora of the South-west Botanical Province susceptible to the pathogen. While direct impacts of P. cinnamomi have been poorly documented in the South-west Botanical Province, even less attention has been given to indirect impact where destruction of the habitat by the pathogen affects taxa not directly affected by infection. Current poor understanding and quantification of indirect impacts of P. cinnamomi through habitat destruction results in an underestimation of the true impact of the pathogen on the flora of the South-west Botanical Province. Considerable variation of susceptibility to P. cinnamomi among and within families of threatened flora and responses of taxa within the genus Lambertia show how classification within family and genus are poor predictors of species susceptibility. Within apparently susceptible plant species, individuals are resistant to P. cinnamomi infection. Intra-specific variation in susceptibility can be utilised in the long-term management of threatened flora populations and needs to be a high research priority. Current control strategies for conservation of flora threatened by P. cinnamomi integrate hygiene and ex situ conservation with disease control using fungicide. Application of the fungicide phosphite has proven effective in slowing progress of P. cinnamomi in infested, threatened communities. However, variation in plant species responses to phosphite application is a major factor influencing effective control of P. cinnamomi in native communities. A greater understanding of the mechanisms of action of phosphite in plant species showing different responses to the fungicide may provide options for prescription modification to increase phosphite effectiveness in a range of plant species. The range of responses to P. cinnamomi infection and phosphite application described for Lambertia taxa suggests that the genus would make an ideal model system to elucidate the mechanisms of resistance to P. cinnamomi and the effectiveness of phosphite against the pathogen.
16
McDougall, K. L., G. E. St J. Hardy e R. J. Hobbs. "Distribution of Phytophthora cinnamomi in the northern jarrah (Eucalyptus marginata) forest of Western Australia in relation to dieback age and topography". Australian Journal of Botany 50, n. 1 (2002): 107. http://dx.doi.org/10.1071/bt01040.
Testo completoAbstract (sommario):
The spatial distribution of Phytophthora cinnamomi Rands at seven dieback sites in the jarrah (Eucalyptus marginata Donn. ex Smith) forest of Western Australia was determined by the following two baiting techniques: in situ baiting with live Banksia grandis Willd. seedlings and ex situ baiting of sampled soil and root material. Four areas within each site were sampled, reflecting dieback age and position in the landscape. Approximate dieback ages of 50, 20 and 5 years were determined by aerial photography. The 50-year-old age class was divided into wet valley floor and dry gravelly slope. Phytophthora cinnamomi was recovered most frequently from the 5-year-old (dieback fronts) and wet 50-year-old areas by both baiting techniques. It was recovered from more than twice as many areas and about five times as many samples when in situ B. grandis baits were used compared with ex situ soil and root baiting. Almost all recoveries from in situ baits were made between October and December. From both methods, it appears that P. cinnamomi has a patchy distribution within dieback sites in the northern jarrah forest. It is easily detected only on dieback fronts and wet valley floors. On dry gravelly sites affected 20 years or more ago, P. cinnamomi is rare and may even be absent at some sites. This makes confident detection of the pathogen difficult. In situ baiting at least allows a temporal component to the sampling and will be a useful method of detection in areas where P. cinnamomi is rare or transient.
17
Barrett, S., B. L. Shearer, C. E. Crane e A. Cochrane. "An extinction-risk assessment tool for flora threatened by Phytophthora cinnamomi". Australian Journal of Botany 56, n. 6 (2008): 477. http://dx.doi.org/10.1071/bt07213.
Testo completoAbstract (sommario):
A risk-assessment tool was used to investigate the risk of extinction from disease caused by Phytophthora cinnamomi to 33 taxa from the Stirling Range National Park, Western Australia. Criteria used to score risk of extinction were the direct impact of P. cinnamomi on taxa, number of extant or extinct populations, percentage of populations infested by P. cinnamomi, proximity and topographical relationship of populations to P. cinnamomi, proximity of populations to tracks and the number of additional threatening processes. Direct impact scores were derived from mortality curves determined from the survival of taxa after soil inoculation with P. cinnamomi in a shade-house environment. On the basis of the total extinction risk score, nine taxa had a ‘very high’, five had a ‘high’, six a ‘moderate’, eight a ‘low’, four a ‘very low’ and one ‘no’ risk of extinction. Whereas the methodology confirmed the current threatened status of nine taxa, it also identified five taxa, not currently listed, to be at ‘high’ risk of extinction. Other threatening processes identified included fire, herbivory, aerial canker disease and climate change. These combine with P. cinnamomi to push taxa further towards extinction. Quantification of risk of extinction identifies taxa at risk and allows for prioritisation of management actions for currently threatened flora. This risk-assessment methodology combined glasshouse inoculation with habitat and ecological data, current in situ disease impact and proximity to disease and vectors, to enable a more comprehensive assessment of extinction risk and may be used in other areas with endemic flora threatened by P. cinnamomi.
18
WILLS, R. T. "The ecological impact of Phytophthora cinnamomi in the Stirling Range National Park, Western Australia". Austral Ecology 18, n. 2 (giugno 1993): 145–59. http://dx.doi.org/10.1111/j.1442-9993.1993.tb00439.x.
Testo completo
19
Hüberli, Daniel, Inez C. Tommerup, Mark P. Dobrowolski, Michael C. Calver e Giles E. Hardy. "Phenotypic variation in a clonal lineage of two Phytophthora cinnamomi populations from Western Australia". Mycological Research 105, n. 9 (settembre 2001): 1053–64. http://dx.doi.org/10.1016/s0953-7562(08)61967-x.
Testo completo
20
Burgess, T. I., J. Edwards, A. Drenth, T. Massenbauer, J. Cunnington, R. Mostowfizadeh-Ghalamfarsa, Q. Dinh et al. "Current status of Phytophthora in Australia". Persoonia - Molecular Phylogeny and Evolution of Fungi 47, n. 1 (31 dicembre 2021): 151–77. http://dx.doi.org/10.3767/persoonia.2021.47.05.
Testo completoAbstract (sommario):
Among the most economically relevant and environmentally devastating diseases globally are those caused by Phytophthora species. In Australia, production losses in agriculture and forestry results from several well-known cosmopolitan Phytophthora species and infestation of natural ecosystems by Phytophthora cinnamomi have caused irretrievable loss to biodiversity, especially in proteaceous dominated heathlands. For this review, all available records of Phytophthora in Australia were collated and curated, resulting in a database of 7869 records, of which 2957 have associated molecular data. Australian databases hold records for 99 species, of which 20 are undescribed. Eight species have no records linked to molecular data, and their presence in Australia is considered doubtful. The 99 species reside in 10 of the 12 clades recognised within the complete phylogeny of Phytophthora. The review includes discussion on each of these species? status and additional information provided for another 29 species of concern. The first species reported in Australia in 1900 was Phytophthora infestans. By 2000, 27 species were known, predominantly from agriculture. The significant increase in species reported in the subsequent 20 years has coincided with extensive surveys in natural ecosystems coupled with molecular taxonomy and the recognition of numerous new phylogenetically distinct but morphologically similar species. Routine and targeted surveys within Australian natural ecosystems have resulted in the description of 27 species since 2009. Due to the new species descriptions over the last 20 years, many older records have been reclassified based on molecular identification. The distribution of records is skewed toward regions with considerable activity in high productivity agriculture, horticulture and forestry, and native vegetation at risk from P. cinnamomi. Native and exotic hosts of different Phytophthora species are found throughout the phylogeny; however, species from clades 1, 7 and 8 are more likely to be associated with exotic hosts. One of the most difficult challenges to overcome when establishing a pest status is a lack of reliable data on the current state of a species in any given country or location. The database compiled here for Australia and the information provided for each species overcomes this challenge. This review will aid federal and state governments in risk assessments and trade negotiations by providing a comprehensive resource on the current status of Phytophthora species in Australia.
21
Khdiar, Mohammed Y., Paul A. Barber, Giles E. StJ Hardy, Chris Shaw, Emma J. Steel, Cameron McMains e Treena I. Burgess. "Association of Phytophthora with Declining Vegetation in an Urban Forest Environment". Microorganisms 8, n. 7 (29 giugno 2020): 973. http://dx.doi.org/10.3390/microorganisms8070973.
Testo completoAbstract (sommario):
Urban forests consist of various environments from intensely managed spaces to conservation areas and are often reservoirs of a diverse range of invasive pathogens due to their introduction through the nursery trade. Pathogens are likely to persist because the urban forest contains a mixture of native and exotic plant species, and the environmental conditions are often less than ideal for the trees. To test the impact of different land management approaches on the Phytophthora community, 236 discrete soil and root samples were collected from declining trees in 91 parks and nature reserves in Joondalup, Western Australia (WA). Sampling targeted an extensive variety of declining native trees and shrubs, from families known to be susceptible to Phytophthora. A sub-sample was set aside and DNA extracted for metabarcoding using Phytophthora-specific primers; the remaining soil and root sample was baited for the isolation of Phytophthora. We considered the effect on the Phytophthora community of park class and area, soil family, and the change in canopy cover or health as determined through sequential measurements using remote sensing. Of the 236 samples, baiting techniques detected Phytophthora species from 24 samples (18 parks), while metabarcoding detected Phytophthora from 168 samples (64 parks). Overall, forty-four Phytophthora phylotypes were detected. Considering only sampling sites where Phytophthora was detected, species richness averaged 5.82 (range 1–21) for samples and 9.23 (range 2–24) for parks. Phytophthora multivora was the most frequently found species followed by P. arenaria, P. amnicola and P. cinnamomi. While park area and canopy cover had a significant effect on Phytophthora community the R2 values were very low, indicating they have had little effect in shaping the community. Phytophthora cinnamomi and P. multivora, the two most invasive species, often co-occurring (61% of samples); however, the communities with P. multivora were more common than those with P. cinnamomi, reflecting observations over the past decade of the increasing importance of P. multivora as a pathogen in the urban environment.
22
Howard, Kay, Ian J. Colquhoun e Giles Hardy. "The potential of copper sulphate to control Phytophthora cinnamomi during bauxite mining in Western Australia". Australasian Plant Pathology 27, n. 1 (1998): 51. http://dx.doi.org/10.1071/ap98006.
Testo completo
23
Murray, DIL. "Rhizosphere Microorganisms From the Jarrah Forest of Western Australia and Their Effects on Vegetative Growth and Sporulation in Phytophthora cinnamomi Rands". Australian Journal of Botany 35, n. 5 (1987): 567. http://dx.doi.org/10.1071/bt9870567.
Testo completoAbstract (sommario):
Soil dilution plate techniques were used to compare the numbers of bacteria, actinomycetes and fungi in the rhizospheres of Acacia pulchella, Banksia grandis and Eucalyptus marginata (jarrah). The most frequently isolated microorganisms and those detected in significantly different numbers in the rhizospheres of the three species were tested for their effects on sporangium production, zoospore discharge, zoospore germination and mycelial growth of the jarrah dieback pathogen Phytophthora cinnamomi. The total population of fungi in rhizosphere soil from B. grandis was much greater than that found in the rhizospheres of the other two species while the convesse was true for bacteria and actinomycetes, of which the largest populations were associated with A. pulchella. Penicillium spinulosum outnum- bered the combined population of other fungi in the Banksia rhizosphere but formed a much smaller proportion of the jarrah and Acacia rhizosphere microfloras, particularly the latter. P. spinulosum had no effect on mycelial growth or zoospore discharge in P. cinnamomi; it had some ability to stimulete sporangium production and, although it partly suppressed spore germination, the inhibitory effect was less pronounced than that noted for most other microorganisms. In contrast, microorganisms which strongly inhibited mycelial growth, zoospore discharge and germination represented a greater proportion of the Acacia rhizosphere microflora compared with the other microfloras, especially that of B. grandis. While some actinornycetes and fungi produced antibiotics that inhibited vegetative growth of P. cinnamomi in dual cultures, mycelial inhibition was often attributable to nutrient depletion of agar media by the test microorganisms. Similarly, nutrient deprivation resulting from microbial competition for substrates was also considered to be the stimulus for sporangium production in liquid media. The results are discussed in relation to previously reported suppression of P. cinnamomi in forest soils beneath stands of A. pulchella and the associated implications of this for biological control of jarrah dieback.
24
Gerritse, RG, JA Adeney, G. Baird e I. Colquhoun. "The reaction of copper ions and hypochlorite with minesite soils in relation to fungicidal activity". Soil Research 30, n. 5 (1992): 723. http://dx.doi.org/10.1071/sr9920723.
Testo completoAbstract (sommario):
Phytophthora cinnamomi is a soil-borne pathogenic fungus and is the primary cause of dieback disease in the jarrah forests of south-west Western Australia. Treatments are needed to eliminate the fungus from infected soils. Compounds containing cupric ions (Cu2+) or hypochlorite (ClO-) have a known fungicidal activity against P. cinnamomi, but their efficacy is affected by soil factors. This study explores the possibility of containing P. cinnamomi by treatment of surface materials for haul roads at minesites in infected areas with these compounds. Solution concentrations of Cu2+ between 50 and 100 mg/L are considered to be fungicidally effective against P. cinnamomi. In samples from the lateritic regolith at the Huntly minesite of Alcoa in Western Australia, concentrations in this range are obtained after adding about 0-5 g (range = 0.3-1 g) of Cu2+ per kg of regolith material. Soil materials from mineral sand areas on the Swan Coastal Plain in Western Australia adsorb Cu2+ less strongly than the regolith materials from the Huntly minesite. Addition of about 0.1-0.2 g Cu2+ per kg is sufficient to reach a fungicidal concentration in solution in these soil materials. Movement of Cu2+ from treated surfaces of haul roads to groundwater and surface water can present a problem. For a single application, travel times of Cu2+ in both lateritic regolith and sandy soils were calculated to be = 200 years per metre. A single treatment of materials from the lateritic regolith would be effective for a period of 2-10 years, depending on the selected material. Sandy soils would have to be treated once or twice a year. Colloidal particles in both surface runoff and throughflow can contribute significantly to the spread of copper in the lateritic regolith, but much less in sandy soils. Hypochlorite is rapidly reduced to chloride by organic matter in soils. At additions of about 0.5 g ClO- per gram of organic carbon, however, hypochlorite can be an effective fungicide against P. cinnamomi.
25
Burgess, Treena I., Janet L. Webster, Juanita A. Ciampini, Diane White, Giles E. StJ Hardy e Michael J. C. Stukely. "Re-evaluation of Phytophthora Species Isolated During 30 Years of Vegetation Health Surveys in Western Australia Using Molecular Techniques". Plant Disease 93, n. 3 (marzo 2009): 215–23. http://dx.doi.org/10.1094/pdis-93-3-0215.
Testo completoAbstract (sommario):
For 30 years, large-scale aerial photography has been used to map the extent of Phytophthora dieback disease in native forests in the southwest of Western Australia, with validation of the observations involving routine testing of soil and root samples for the presence of Phytophthora cinnamomi. In addition to P. cinnamomi, six morpho-species have been identified using this technique: P. citricola, P. megasperma, P. cryptogea, P. drechsleri, P. nicotianae, and P. boehmeriae. In recent years, many new Phytophthora species have been described worldwide, often with similar morphology to existing species; thus, as many of the isolates collected in Western Australia have been difficult to identify based on morphology, molecular identification of the morpho-species is required. Based on amplification of the internal transcribed spacer (ITS) region of the rDNA gene, sequence data of more than 230 isolates were compared with those of existing species and undescribed taxa. P. inundata, P. asparagi, P. taxon PgChlamydo, P. taxon personii, and P. taxon niederhauserii were identified based on sequence data. Phylogenetic analysis revealed that nine potentially new and undescribed taxa can be distinguished. Several of the new taxa are morphologically indistinguishable from species such as P. citricola, P. drechsleri, and P. megasperma. In some cases, the new taxa are closely related to species with similar morphology (e.g., P.sp.4 and P. citricola). However, the DNA sequences of other new taxa such as P.sp.3 and P.sp.9 show that they are not closely related to morphologically similar species P. drechsleri and P. megasperma, respectively. Most of the new taxa have been associated with dying Banksia spp., while P.sp.2 and P.sp.4 have also been isolated from dying Eucalyptus marginata (jarrah). Some taxa (P.sp.3, 6, and 7) appear to have limited distribution, while others like P.sp.4 are widespread.
26
Jeff-Ego, Olumide, Juliane Henderson, Bruce Topp, Andre Drenth e Olufemi Akinsanmi. "Variations in macadamia varietal susceptibility to Phytophthora multivora and P. cinnamomi". Proceedings 36, n. 1 (21 febbraio 2020): 109. http://dx.doi.org/10.3390/proceedings2019036109.
Testo completoAbstract (sommario):
Incidence of diseases caused by various Phytophthora spp. in macadamia is increasing worldwide, often resulting in severe yield loss and death of both juvenile and old macadamia trees. In Australia, P. cinnamomi and P. multivora has been identified to cause severe stem canker in macadamia orchards. Currently, various varietal improvement research programs on macadamia are underway, not only to obtain high-yielding and precocious macadamia germplasm but to develop macadamia genotypes with acceptable levels of tolerance/resistance to pests and diseases. In this study, we selected macadamia genotypes for their acceptable levels of tolerance/resistance to Phytophthora infection, after screening about 360 macadamia genotypes against to P. cinnamomi and P. multivora, using a rapid detached leaf and plant inoculation assays. These macadamia plant materials were collected from a major macadamia arboretum in Queensland. Our results revealed segregation of macadamia genotypes into two spectrum of susceptible and tolerant macadamia genotypes. Hence, strong representatives within the tolerant and susceptible spectrum were further investigated in order to understand if the basis of the differential response is driven by a variation in structural, physiological or genetic markers, following a challenge with Phytophthora spp. Our result revealed a marked variation in structural response during the infection process, between the selected susceptible, ‘HAES816’ and tolerant germplasm and ‘HAES344’. This information will provide evidence to support potential preferential selection of tolerant macadamia genotypes potentially useful for breeding against Phytophthora diseases. Further studies will characterize tolerant macadamia progenies to develop marker-assisted selection protocols for resistance, and explore defense mechanisms response.
27
Hill, TCJ, JT Tippett e BL Shearer. "Invasion of Bassendean Dune Banksia Woodland by Phytophthora cinnamomi". Australian Journal of Botany 42, n. 6 (1994): 725. http://dx.doi.org/10.1071/bt9940725.
Testo completoAbstract (sommario):
The rate and mechanism of the spread of Phytophthora cinnamomi in Banksia woodland of the Bassendean Dune system north of Perth, Western Australia was studied. Aerial photographs were used to measure the spread of disease in fronts longer than 5 km over 35 years. Fronts in upper slope positions moved downhill and uphill at 1.01 and 1.13 m year-1, respectively, while fronts in low-lying positions moved downgrade and upgrade (with and against the direction of water table flow) at 1.30 and 1.20 m year-1, respectively. Fronts in low-lying areas spread significantly faster than those on upper slopes. Excavations to 2 m depth of the root systems of 21 dying plants of Banksia attenuata R.Br., an overstorey co-dominant, revealed that 28% (3.9 roots/tree) of all first-order roots were infected. Assessment of the proportion of roots infected revealed a significant (P < 0.01) departure from uniform distribution of disease down the profile in both upper slope and drained flat sites. In 14 trees on dune slopes, 6-40 m above the aquifer, infection rate was higher than expected in roots lying at 21-40 cm depth, but lower than expected in roots below 1 m. Seventy three percent of infected roots lay in the top 40 cm of soil. In seven trees on a drained flat, 2-3 m above the aquifer, infection rate was high in the 21-60 cm horizon and also in roots below 1 m. Even though Phytophthora cinnamomi was active in the vicinity of the water table in trees on drained flats, the slow, steady spread of the disease in all landscape positions suggested that the primary mode of fungal invasion was through roots of susceptible vegetation. No evidence was found of accelerated spread of disease caused by the dispersal of zoospores.
28
Kennedy, J., e G. Weste. "Vegetation Changes Associated With Invasion by Phytophthora cinnamomi on Monitored Sites in the Grampians, Western Australia". Australian Journal of Botany 34, n. 3 (1986): 251. http://dx.doi.org/10.1071/bt9860251.
Testo completoAbstract (sommario):
The effects of invasion by Phytophthora cinnamomi were measured on sites representing the larger forest regions of the Grampians. Changes were obvious at first, with the death of more than 50% of the species including large plants such as Xanthorrhoea australis, but soon became dificult to detect as susceptible species were replaced by field-resistant graminoids. Reductions were assessed in species heterogeneity and plant density during 1976, at the onset of disease and from 1977 to 1984. Susceptible species disappeared from infested forest and no re-emergence was observed. Less-susceptible plants such as some Euca/yptus spp. declined in number, regeneration and size, due to deaths or dieback of the branches. Reductions in tree canopy and the loss of structural dominants of the understorey caused changes in the flora which are likely to persist. The survival of rare, susceptible endemic species may be endangered. On dry, steep slopes the dead plants were not replaced and the amount of bare ground increased causing erosion of the soil surface. Some graminoid species increased in abundance on level, infested sites, resulting in a different species composition but with both species heterogeneity and plant density numerically similar to the previous flora.
29
Olde, Peter. "Grevillea pieroniae Olde (Proteaceae: Grevilleoideae: Hakeinae), a rare new species in the Triloba Group from the Stirling Range, Western Australia, and a short history of the group." Telopea 23 (2020): 227–35. http://dx.doi.org/10.7751/telopea14783.
Testo completoAbstract (sommario):
Twenty-one Grevillea species currently comprise the Triloba Group sensu Flora of Australia, or Group 1 sensu The Grevillea Book. All species except the transcontinental species G. anethifolia R.Br. are distributed in southwest Western Australia. Grevillea pieroniae Olde, herein described, is currently treated as Grevillea sp. Stirling Range (D.J. McGillivray 3488 & A.S. George) by the Western Australian Herbarium. It has some affinity with Grevillea anethifolia through shared possession of similar truncate-conical to cylindrical pollen-presenters. Grevillea pieroniae is a rare species that is potentially threatened by Phytophthora cinnamomi, fire frequency, a drying climate, as well as grazing by feral and native herbivores, so requires careful assessment and ongoing monitoring. A short history of the Triloba Group is provided to give context to Grevillea pieroniae and as precursor to other related species soon to be recognised.
30
Dundas, Shannon J., Patricia A. Fleming e Giles E. St J. Hardy. "Flower visitation by honey possums (Tarsipes rostratus) in a coastal banksia heathland infested with the plant pathogen Phytophthora cinnamomi". Australian Mammalogy 35, n. 2 (2013): 166. http://dx.doi.org/10.1071/am12044.
Testo completoAbstract (sommario):
The honey possum (Tarsipes rostratus) is a tiny (7–10 g) obligate nectarivore endemic to south-west Western Australia that relies on high floristic diversity for year-round nectar and pollen resources. We investigated flower visitation by honey possums at a site in the presence of the plant pathogen Phytophthora cinnamomi by sampling pollen on the head of captured and radio-tracked individuals. The aim of the study was to identify plant species that were visited and to compare these with known susceptibility to Phytophthora to assess the potential impact of further spread of the pathogen on honey possums. Nine plant taxa were regularly identified from pollen on honey possums, including four Banksia species. Six of the nine plant taxa identified (Banksia plumosa, Adenanthos cuneatus, Calothamnus gracilis, B. brunnea, B. nutans, B. tenuis) were most frequently visited by honey possums, each making up >20% of pollen grains for at least one season. Five of the nine plant taxa are known to be susceptible to Phytophthora, which substantially changes vegetation composition in its wake. The inevitable spread of Phytophthora is postulated to result in the localised loss of resources for honey possums and is a concern for on-going conservation management.
31
Bradshaw, S. D., R. D. Phillips, S. Tomlinson, R. J. Holley, S. Jennings e F. J. Bradshaw. "Ecology of the Honey possum, Tarsipes rostratus, in Scott National Park, Western Australia". Australian Mammalogy 29, n. 1 (2007): 25. http://dx.doi.org/10.1071/am07003.
Testo completoAbstract (sommario):
The Honey possum, Tarsipes rostratus, is an obligate nectarivore, known to feed on plant species from only three Families in south-western Western Australia: Myrtaceae, Proteaceae and Epacridaceae. These plants can be adversely affected by fire, decreased rainfall or groundwater levels and the pathogen Phytophthora cinnamomi. We investigated the ecology of T. rostratus in terms of: (i) how the population fluctuated in response to rainfall and fire over a 20-year period and (ii) changes in diet and movements during a period of decreased food availability in late summer. Mean capture rates were significantly positively correlated with mean flowering rates of Banksia ilicifolia over a 20-year period. Winter capture rates were also significantly positively correlated with both annual and winter rainfall two years prior to trapping in recently burnt areas, but not in long unburnt� areas. Capture rates were significantly higher in unburnt Banksia woodland during winter but densities there have declined since 1996, associated with the death of many Banksia ilicifolia trees from persistent Phytophthora infection. Notwithstanding this decline, winter capture rates in the unburnt areas were still approximately double those in the burnt areas 6 years after the last fire. Short-term capture rates were negatively correlated with barometric pressure, showing that movement and foraging is stimulated by the passage of low pressure frontal weather systems. Despite the paucity of known food sources flowering in late summer and autumn, there was no evidence of T. rostratus using plant species from other than the three above-noted Families. Utilisation areas in summer were also no larger than those previously recorded across all seasons in Scott National Park. Some individuals, however, moved extensive distances to locate spatially restricted food sources. The conservatism of their diet and the sensitivity of the population to changes in rainfall and fire history indicate that T. rostratus populations are particularly vulnerable to some of the environmental changes now occurring in south-western Australia.
32
Podger, FD. "Comparative Pathogenicity of Fourteen Australian Isolates of Phytophthora cinnamomi Determined on Transplants of Tasmanian Temperate Heathland". Australian Journal of Botany 37, n. 6 (1989): 491. http://dx.doi.org/10.1071/bt9890491.
Testo completoAbstract (sommario):
Peat cores containing mature plants of 21 native species were transplanted from heathland in south- western Tasmania to a greenhouse and inoculated individually with 14 Australian isolates of Phytophthora cinnamomi. The isolates, which had been obtained from 10 different species of host plants and from 14 localities widely distributed across the continent, included three of the four isotypes of the fungus known to occur in Australia. Abnormal coloration, root-rot and death occurred in 9 of the 11 species of dicotyledons present; in a single plant of one species of the 11 monocotyledons but in neither of the two ferns. Of the nine species of dicotyledons in which disease occurred, five species were highly susceptible. Comparisons of the relative pathogenicity of isolates, based on the response of the five highly susceptible species, showed no evidence of strong differences in pathogenicity between groups of isolates, whether these groups were based on isotype of the fungus, climate at the source of the isolates or taxonomic affinity of the host plants from which they were originally isolated.
33
Smith, K. J., P. A. Fleming, T. L. Kreplins e B. A. Wilson. "Population monitoring and habitat utilisation of the ash-grey mouse (Pseudomys albocinereus) in Western Australia". Australian Mammalogy 41, n. 2 (2019): 170. http://dx.doi.org/10.1071/am17061.
Testo completoAbstract (sommario):
Although Australia has a diverse native rodent fauna, the population dynamics and habitat requirements of most species have not yet been identified. Effective management for conservation of these species is therefore hindered. The aim of the present study was to investigate the habitat use and population dynamics of the ash-grey mouse (Pseudomys albocinereus) through trapping and radio-tracking in Boonanarring Nature Reserve, Western Australia. Although there was no relationship between capture rate and time since fire, ash-grey mice selected dense understorey vegetation. Burrows (47% of 19 unique daytime locations), Xanthorrhoea spp. (26%), tree hollows (11%), shrubs (11%), and logs were selected as daytime refuges. Mean (±s.e.) short-term home-range size was 1.70±0.97ha (n=9) (maximum=9.15ha). There was some evidence that ash-grey mice may be excluded from favourable habitat by a high abundance of house mice (Mus musculus). Management to prevent declines of ash-grey mice should minimise threats to significant habitat features – areas with dense understorey vegetation, soils suitable for burrowing, grasstrees, hollow logs, and tree hollows. Suitable management strategies include: retention or rehabilitation of remnant vegetation; exclusion of livestock; low-intensity, small-area burns; and control of weeds, introduced predators and Phytophthora cinnamomi.
34
Wilkinson, C. J., J. M. Holmes, K. M. Tynan, I. J. Colquhoun, J. A. McComb, G. E. St J. Hardy e B. Dell. "Ability of phosphite applied in a glasshouse trial to control Phytophthora cinnamomi in five plant species native to Western Australia". Australasian Plant Pathology 30, n. 4 (2001): 343. http://dx.doi.org/10.1071/ap01055.
Testo completo
35
Anderson, Prue, Mark Brundrett, Pauline Grierson e Richard Robinson. "Impact of severe forest dieback caused by Phytophthora cinnamomi on macrofungal diversity in the northern jarrah forest of Western Australia". Forest Ecology and Management 259, n. 5 (febbraio 2010): 1033–40. http://dx.doi.org/10.1016/j.foreco.2009.12.015.
Testo completo
36
Shearer, BL, e M. Dillon. "Corrigendum - Susceptibility of Plant Species in Banksia Woodlands on the Swan Coastal Plain, Western Australia, to Infection by Phytophthora cinnamomi". Australian Journal of Botany 44, n. 4 (1996): 433. http://dx.doi.org/10.1071/bt9960433c.
Testo completo
37
Pilbeam, Roslyn A., Kay Howard, Bryan L. Shearer e Giles E. St J. Hardy. "Phosphite does not stimulate a wounding response in Eucalyptus marginata seedlings". Australian Journal of Botany 59, n. 4 (2011): 393. http://dx.doi.org/10.1071/bt10252.
Testo completoAbstract (sommario):
Phosphite is used to protect plants from the soilborne plant pathogen, Phytophthora cinnamomi. While several studies have reported a stimulation of defence mechanisms in response to the infection of plants treated with phosphite, the effect of phosphite on abiotic wound repair is unknown. The aim of this histological study was to detail the effects of phosphite on previously undescribed wound repair in Eucalyptus marginata, an important forest tree of south-western Australia, which responds to phosphite treatment. Clonal lines of young plants of E. marginata without a periderm, considered resistant and susceptible to P. cinnamomi, were sprayed with phosphite and the green stems were wounded with liquid nitrogen, where a small area of the vascular cambium was damaged. Transverse hand sections showed phosphite had no effect and there was no genotypic difference on wound responses in E. marginata. Wound periderm and a ligno-suberised boundary zone formed within 7 days. The generation of new phellogen derivatives occurred and by 14 days the vascular cambium was almost fully restored with wound wood formed by 21 days. In the absence of a pathogen, phosphite did not interfere with the quality and speed of wound repair in the E. marginata clones suggesting that wound repair will not be affected when phosphite is used as a prophylactic treatment.
38
Abbott, I. "Recruitment and Mortality in Populations of Banksia grandis Willd. In Western Australian Forest". Australian Journal of Botany 33, n. 3 (1985): 261. http://dx.doi.org/10.1071/bt9850261.
Testo completoAbstract (sommario):
This paper examines seed release and seed dispersal; recruitment in relation to fire and logging; mortality of seedlings in relation to their age; and the dynamics of one population from November 1979 to March 1983. Dehiscence of follicles is caused by wetting and drying of the infructescence, so that most seeds fall to the ground during autumn in the Mediterranean climate of south-western Australia. Seeds are wind- dispersed, settling downward from the parent tree: 90% of seed falls within the first year. There is large variation in annual recruitment of seedlings, reflecting large annual differences in the number of infructescences produced. Fires of various intensities or logging do not enhance recruitment. Seedling mortality is greatest during the first summer after germination; this may be related to the rudimentary development of the lignotuber. A population of 1890 individually marked plants was studied for 3.5 years. Over twice as many deaths took place in summer and autumn as in winter and spring, and 90% of deaths were of plants less than 20 cm tall. At the conclusion of the study, total population size, through recruitment of three cohorts of seedlings, had increased by 7%. This indicates how important control of reproduction would be in achieving long-term reduction in the abundance of B. grandis, which harbours the pathogenic fungus Phytophthora cinnamomi.
39
Bradshaw, S. D., e F. J. Bradshaw. "Long-term recovery from fire by a population of honey possums (Tarsipes rostratus) in the extreme south-west of Western Australia". Australian Journal of Zoology 65, n. 1 (2017): 1. http://dx.doi.org/10.1071/zo16068.
Testo completoAbstract (sommario):
The impact of two fires, six years apart, on the long-term recovery of a population of honey possums (Tarsipes rostratus) in the extreme south-west of Western Australia was documented over a 23-year period. Recovery was relatively rapid after the first fire, with catch rates reaching 78% of precatch levels within six years, but was much slower following the second fire in April 1999. Regression analysis estimates that full recovery to prefire catch rates and densities would take 25.6 years. The spread of Phytophthora cinnamomi (dieback) throughout the study area has severely impacted Banksia ilicifolia trees, which are the honey possums’ primary food source, and the impact has been greater in the burnt than unburnt areas. Analysis of catch-per-unit-effort and density of individual honey possums over the whole 29-year period of the study shows that numbers have not declined in the long-unburnt southern area of the study site, despite the spread of dieback and loss of banksia trees. The data are discussed in relation to the impact of fire on other vertebrate species that have specific habitat requirements. Given predictions of increasing fire frequencies due to climate change and an increased utilisation of prescribed burning to protect human life and property, it is imperative that management of areas harbouring honey possums be protected from too-frequent fire if this iconic species is to persist.
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Howard, Kay, Bernie Dell e Giles E. Hardy. "Phosphite and mycorrhizal formation in seedlings of three Australian Myrtaceae". Australian Journal of Botany 48, n. 6 (2000): 725. http://dx.doi.org/10.1071/bt00007.
Testo completoAbstract (sommario):
Currently in Western Australia, phosphite is being used to contain the root and collar rot pathogen, Phytophthora cinnamomi, in native plant communities. There have been reports of negative effects of phosphite on arbuscular mycorrhiza (AM), so there are concerns that it may have a deleterious effect on other mycorrhizal fungi. Two glasshouse experiments were undertaken to determine the impact of phosphite on eucalypt-associated ectomycorrhizal fungi. In the first experiment, non-mycorrhizal seedlings of Eucalyptus marginata, Eucalyptus globulus and Agonis flexuosa were sprayed to runoff with several concentrations of phosphite, and then planted into soil naturally infested with early colonising mycorrhizal species. Assessments were made of percentage of roots infected with mycorrhizal fungi. There was no significant effect on ectomycorrhizal formation but there was a four-fold increase in AM colonisation of A. flexuosa roots with phosphite application. In the second experiment, E. globulus seedlings mycorrhizal with Pisolithus, Scleroderma and Descolea were treated with different levels of phosphite and infection of new roots by ectomycorrhizal fungi was assessed. There was no significant effect on ectomycorrhizal formation when phosphite was applied at the recommended rate (5 g L–1), while at 10 g L–1 phosphite significantly decreased infection by Descolea.
41
Park, Ja-On, Krishnapillai Sivasithamparam, Emile Ghisalberti, Jaih Hargreaves, Walter Gams e Anthony L. J. Cole. "Cuticular disruption and mortality of Caenorhabditis elegans exposed to culture filtrate of Byssochlamys nivea Westling". Nematology 3, n. 4 (2001): 355–63. http://dx.doi.org/10.1163/156854101317020277.
Testo completoAbstract (sommario):
AbstractA strain of a Byssochlamys nivea, isolated from saline mud in Western Australia as a part of statewide survey of soil fungi for nematophagous activity, was evaluated for its effect on nematodes. Culture filtrate of the fungus grown on potato dextrose broth for 7 days caused structural changes in the cuticle, aggregation of individuals, and mortality of Caenorhabditis elegans. In addition, the culture filtrate completely inhibited hatching of C. elegans eggs. Exudates from agar colonies also caused cuticular disruption and mortality of C. elegans. The cuticular disruption observed, not reported in nematodes before, was initiated in the labial region and spread towards the posterior region of the nematode within 10 min of application. This reaction occurred only in live nematodes. Cuticular disruption and mortality caused by the culture filtrate varied according to growth conditions. The active compound(s) in the culture filtrate were thermostable (100°C for 1 h); however freezing the culture filtrate (-20°C for 2 days) eliminated the activities, as did dialysis (<14 000 molecular weight). Cuticular disruption and mortality were also observed when the nematode was exposed to culture filtrates of two other strains of B. nivea supplied by CBS, The Netherlands. The culture filtrate also inhibited in vitro growth of the plant-pathogenic fungi Fusarium oxysporum, Gaeumannomyces graminis var. tritici, Phytophthora cinnamomi, Pythium irregulare and Rhizoctonia solani.
42
O'Rourke, Tiernan A., Tim T. Scanlon, Megan H. Ryan, Len J. Wade, Alan C. McKay, Ian T. Riley, Hua Li, Krishnapillai Sivasithamparam e Martin J. Barbetti. "Severity of root rot in mature subterranean clover and associated fungal pathogens in the wheatbelt of Western Australia". Crop and Pasture Science 60, n. 1 (2009): 43. http://dx.doi.org/10.1071/cp08187.
Testo completoAbstract (sommario):
Pasture decline is considered to be a serious challenge to agricultural productivity of subterranean clover across southern Australia. Root disease is a significant contributing factor to pasture decline. However, root disease assessments are generally carried out in the early part of the growing season and in areas predominantly sown to permanent pastures. For this reason, in spring 2004, a survey was undertaken to determine the severity of root disease in mature subterranean clover plants in pastures located in the wheatbelt of Western Australia. DNA-based soil assays were used to estimate population density in the soil of a variety of soil-borne pathogens known to commonly occur in the Mediterranean-type environments of southern Australia. The relationships between severity of disease on tap and lateral roots and root diameter, root length, nodulation, and total rainfall were determined. The survey showed, for the first time, that severe root disease is widespread in spring across the wheatbelt of Western Australia. There was a positive correlation between rainfall and tap root disease, and between tap root disease and average root diameter of the entire root system. Despite the high levels of root disease present across the sites, the DNA of most root disease pathogens assayed was detected in trace concentrations. Only Pythium Clade F showed high DNA concentrations in the soil. DNA concentrations in the soil, in particular for Phytophthora clandestina and Rhizoctonia solani AG 2.1 and AG 2.2, were higher in the smaller autumn sampling in 2006. This study suggests that the productivity of subterranean clover-based pastures is severely compromised by root rot diseases throughout the growing season in the wheatbelt of Western Australia.
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Bakonyi, J., Z. Á. Nagy e T. Érsek. "First Report of Phytophthora citricola on False Cypress in Hungary". Plant Disease 90, n. 10 (ottobre 2006): 1358. http://dx.doi.org/10.1094/pd-90-1358c.
Testo completoAbstract (sommario):
In May 2005, an estimated 10 to 15% mortality of various cultivars of false cypress (also named Lawson cypress or Port-Orford-cedar [Chamaecyparis lawsoniana]) with severe wilt was observed in field stands of an ornamental nursery in western Hungary. Wilted plants had rot-associated reduction of their root system. Root discoloration and occasional chlorosis of lower leaves commenced on potted 3-year-old plants that were held in the open air for 10 to 12 months before planting. Four species of Phytophthora (P. lateralis, P. eriugena, P. hibernalis, and P. cinnamomi) have been reported on this host (2). Direct plating of discolored roots from the most susceptible cultivar (Silver Globus) onto a selective potato dextrose agar or carrot agar medium yielded pure cultures that developed white, stellate colonies with sparse aerial mycelia. The hyphal growth was optimal at 25°C, but the growth above 32°C and below 4°C was completely inhibited. Single, terminal sporangia on simple (occasionally sympodial) sporangiophores formed abundantly in nonsterile soil filtrate but not in agar. Sporangia, 31 to 67 μm (59.1 ± 9.3 μm) long and 25 to 39 μm (31.5 ± 4.0 μm) wide, were noncaducous and semipapillate, variable in shape, mostly obpyriform, rarely obovoid, ovoid-ellipsoid and spherical or bifurcated and distorted, and the exit pore was narrow (7.2 ± 0.8 μm). No external or internal proliferation and no hyphal swellings or chlamydospores were observed. The isolates were homothallic with smooth-walled oogonia (27.3 ± 3.4 μm in diameter) and paragynous antheridia. The oospores (24.7 ± 2.1 μm in diameter) were plerotic. The morpho-physiological features suggested that our isolates belonged to Waterhouse's Group III, and in particular, represented P. citricola. This was confirmed by cellulose acetate electrophoresis of malate dehydrogenase; the isozyme pattern of false cypress isolate was identical to that of the ITS-sequenced (NCBI Accession No. AY366193) P. citricola isolate from a Hungarian alder forest (1). Pathogenicity tests on four 3-year-old potted false cypress (cv. Silver Globus) plants in the greenhouse resulted in rapidly developing (within 2 weeks) sunken, necrotic lesions at the stem base around the site of wound inoculation with a 5-mm-diameter mycelial agar plug. After 12 weeks, each inoculated plant wilted and died. The causal agent was consistently reisolated from necrotic tissues. In Hungary, P. citricola was first isolated and identified from alder forest soil (1). Nonetheless that false cypress has been listed as the host of P. citricola in Norway and Poland (3,4), to our knowledge, this report is the first definitive description of this Phytophthora sp. on this host. References: (1) J. Bakonyi et al. Plant Pathol. 52:807, 2003. (2) D. C. Erwin and O. K. Ribeiro. Pages 282–287 in: Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (3) V. Talgø V. and A. Stensvand. Grønn kunnskap e 7(101G):1, 2003. (4) K. Wiejacha et al. Page 45 in: Improvement and Unification of Plant Disease Diagnostics. Abstracts of International Workshop, Skierniewice, Poland, 2004.
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O'Rourke, Tiernan A., Megan H. Ryan, Hua Li, Xuanli Ma, Krishnapillai Sivasithamparam, Jamshid Fatehi e Martin J. Barbetti. "Taxonomic and pathogenic characteristics of a new species Aphanomyces trifolii causing root rot of subterranean clover (Trifolium subterraneum) in Western Australia". Crop and Pasture Science 61, n. 9 (2010): 708. http://dx.doi.org/10.1071/cp10040.
Testo completoAbstract (sommario):
Subterranean clover (Trifolium subterraneum) is grown extensively as a pasture legume in agronomic regions with Mediterranean-type climates in parts of Africa, Asia, Australia, Europe, North America and South America. Root diseases of subterranean clover, especially those caused by oomycete pathogens including Aphanomyces, Phytophthora and Pythium, greatly reduce productivity by significantly decreasing germination, seedling establishment, plant survival and seed set. For this reason, experiments were conducted to determine the species of Aphanomyces causing root disease on subterranean clover in the high-rainfall areas of south-west Western Australia. The effects of flooding, temperature and inoculum concentration on the development of root disease on subterranean clover caused by this Aphanomyces sp. were also investigated as was its host range. Morphological and molecular characteristics were used to identify the pathogen as a new species Aphanomyces trifolii sp. nov. (O’Rourke et al.), which forms a distinct clade with its nearest relative being A. cladogamus. A. trifolii caused significant lateral root pruning as well as hypocotyl collapse and tap root disease of subterranean clover. The level of disease was greater in treatments where soil was flooded for 24 h rather than for 6 h or in unflooded treatments. The pathogen caused more disease at 18/13oC than at lower (10/5oC) or higher (25/20oC) temperatures. The pathogen caused more disease at 1% inoculum than at 0.5 or 0.2% (% inoculum : dry weight of soil). In greenhouse trials, A. trifolii also caused root disease on annual medic (M. polymorpha and M. truncatula), dwarf beans (Phaseolus vulgaris) and tomatoes (Solanum lycopersicum). However, the pathogen did not cause disease on peas (Pisum sativum), chickpea (Cicer arietinum), wheat (Triticum aestivum), annual ryegrass (Lolium rigidium) or capsicum (Capsicum annuum). A. trifolii is a serious pathogen in the high-rainfall areas of south-west Western Australia and is likely a significant cause of root disease and subsequent decline in subterranean clover pastures across southern Australia.
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Lamont, Byron B., Neal J. Enright, E. T. F. Witkowski e J. Groeneveld. "Conservation biology of banksias: insights from natural history to simulation modelling". Australian Journal of Botany 55, n. 3 (2007): 280. http://dx.doi.org/10.1071/bt06024.
Testo completoAbstract (sommario):
We have studied the ecology and conservation requirements of Banksia species in the species-rich sandplains of south-western Australia for 25 years. Loss of habitat through land-clearing has had the greatest impact on their conservation status over the last 50 years. Ascertaining optimal conditions for conservation management in bushland requires detailed knowledge of the species under consideration, including demographic attributes, fire regime, growing conditions and interactions with other species. Where populations have been fragmented, seed production per plant has also fallen. The group most vulnerable to the vagaries of fire, disease, pests, weeds and climate change are the non-sprouters, rather than the resprouters, with population extinction so far confined to non-sprouting species. Recent short-interval fires (<8 years) appear to have had little impact at the landscape scale, possibly because they are rare and patchy. Fire intervals exceeding 25–50 years can also lead to local extinction. Up to 200 viable seeds are required for parent replacement in Banksia hookeriana when growing conditions are poor (low post-fire rainfall, commercial flower harvesting) and seed banks of this size can take up to 12 years to be reached. Seed production is rarely limited by pollinators, but interannual seasonal effects and resource availability are important. Genetic diversity of the seed store is quickly restored to the level of the parents in B. hookeriana. Florivores and granivores generally reduce seed stores, although this varies markedly among species. In Banksia tricuspis, black cockatoos actually increase seed set by selectively destroying borers. Potential loss of populations through the root pathogen Phytophthora cinnamomi also challenges management, especially in the southern sandplains. Prefire dead plants are a poor source of seeds for the next generation when fire does occur. Harvesting seeds and sowing post-fire have much to commend them for critically endangered species. Bare areas caused by humans can result in ideal conditions for plant growth and seed set. However, in the case of B. hookeriana/B. prionotes, disturbance by humans has fostered hybridisation, threatening the genetic integrity of both species, whereas fine-textured soils are unsuitable for colonisation or rehabilitation. Few viable seeds become seedlings after fire, owing to post-release granivory and herbivory and unsuitable germination conditions. Seedling-competitive effects ensure that season/intensity of fire is not critical to recruitment levels, except in the presence of weeds. Water availability during summer–autumn is critical and poses a problem for conservation management if the trend for declining rainfall in the region continues. Our simulation modelling for three banksias shows that the probability of co-occurrence is maximal when fire is stochastic around a mean of 13 years, and where fire-proneness and post-fire recruitment success vary in the landscape. Modelling results suggest that non-sprouting banksias could not survive the pre-European frequent-fire scenario suggested by the new grasstree technique for south-western Australia. However, we have yet to fully explore the conservation significance of long-distance dispersal of seeds, recently shown to exceed 2.5 km in B. hookeriana.
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Mcnab, W. Henry. "Evidence that Castanea Dentata Persists on Xeric, Mid-Elevation Sites in the Southern Appalachians". Journal of North Carolina Academy of Science 133, n. 1-2 (1 marzo 2017): 23–31. http://dx.doi.org/10.7572/jncas-d-16-00004.1.
Testo completoAbstract (sommario):
Abstract: Castanea dentata (American chestnut) persists today in the southern Appalachian forests of North Carolina as sparsely occurring sprouting root systems. The introduction of two exotic fungal diseases into North America, root rot (Phytophthora cinnamomi) in the early 1800s and chestnut blight (Cryphonectria parasitica) in the early 1900s, eliminated C. dentata as a dominant canopy species. Identifying and understanding the characteristics of sites where C. dentata persists could offer insights for management and restoration. Using a regional forest inventory and analysis (FIA) database, I studied the ecology of C. dentata on 831 forested sample plots in 21 mountainous counties of western North Carolina. The purpose of my study was to determine if the presence of C. dentata was associated with common topographic variables and the co-occurrence of other tree species that could be used in a regression model for evaluation of sites for potential management activities. I found that C. dentata occurred on only 3.5% of the sample plots. Its presence was directly associated with elevation >900 m, positively related to the co-occurring species Quercus prinus (chestnut oak) and Q. rubra (northern red oak), and negatively related to Liriodendron tulipifera (yellow-poplar). Logistic regression revealed poor performance of formulations with multiple significant biological variables (i.e., tree species) because of multicollinearity effects with elevation. Good model performance was achieved with a two-variable formulation using elevation and a weighted averages score derived from direct gradient analysis and ordination of moisture affinities of the 30 tree species in the study plots. An explanation for the effect of elevation on occurrence of C. dentata on sites >900 m is unknown, but the arborescent species scores suggest probable xeric to subxeric plot moisture regimes. Limitations of the FIA data for my study were many including few plots with C. dentata, lack of plot soil characteristics and history of disturbance from fire. Results from my study may have application to rank forest sites for investigation of biological control of C. parasitica through hypovirulence and for identifying stands for application of silvicultural practices to reduce environmental stress and increase survival of existing root systems.
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Nichols, P. G. H., R. A. C. Jones, T. J. Ridsdill-Smith e M. J. Barbetti. "Genetic improvement of subterranean clover (Trifolium subterraneum L.). 2. Breeding for disease and pest resistance". Crop and Pasture Science 65, n. 11 (2014): 1207. http://dx.doi.org/10.1071/cp14031.
Testo completoAbstract (sommario):
Subterranean clover (Trifolium subterraneum L.) is the most widely sown pasture legume in southern Australia and resistance to important diseases and pests has been a major plant-breeding objective. Kabatiella caulivora, the cause of clover scorch, is the most important foliar fungal pathogen, and several cultivars have been developed with resistance to both known races. Screening of advanced breeding lines has been conducted to prevent release of cultivars with high susceptibility to other important fungal foliar disease pathogens, including rust (Uromyces trifolii-repentis), powdery mildew (Oidium sp.), cercospora (Cercospora zebrina) and common leaf spot (Pseudopeziza trifolii). Several oomycete and fungal species cause root rots of subterranean clover, including Phytophthora clandestina, Pythium irregulare, Aphanomyces trifolii, Fusarium avenaceum and Rhizoctonia solani. Most breeding efforts have been devoted to resistance to P. clandestina, but the existence of different races has confounded selection. The most economically important virus diseases in subterranean clover pastures are Subterranean clover mottle virus and Bean yellow mosaic virus, while Subterranean clover stunt virus, Subterranean clover red leaf virus (local synonym for Soybean dwarf virus), Cucumber mosaic virus, Alfalfa mosaic virus, Clover yellow vein virus, Beet western yellows virus and Bean leaf roll virus also cause losses. Genotypic differences for resistance have been found to several of these fungal, oomycete and viral pathogens, highlighting the potential to develop cultivars with improved resistance. The most important pests of subterranean clover are redlegged earth mite (RLEM) (Halotydeus destructor), blue oat mite (Penthaleus major), blue-green aphid (Acyrthosiphon kondoi) and lucerne flea (Sminthurus viridis). New cultivars have been bred with increased RLEM cotyledon resistance, but limited selection has been conducted for resistance to other pests. Screening for disease and pest resistance has largely ceased, but recent molecular biology advances in subterranean clover provide a new platform for development of future cultivars with multiple resistances to important diseases and pests. However, this can only be realised if skills in pasture plant pathology, entomology, pre-breeding and plant breeding are maintained and adequately resourced. In particular, supporting phenotypic disease and pest resistance studies and understanding their significance is critical to enable molecular technology investments achieve practical outcomes and deliver subterranean clover cultivars with sufficient pathogen and pest resistance to ensure productive pastures across southern Australia.
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Lamont, Byron B., Roy Wittkuhn e Dylan Korczynskyj. "Ecology and ecophysiology of grasstrees". Australian Journal of Botany 52, n. 5 (2004): 561. http://dx.doi.org/10.1071/bt03127.
Testo completoAbstract (sommario):
‘Xanthorrhoea…is in habit one of the most remarkable genera of Terra Australis, and gives a peculiar character to the vegetation of that part of the country where it abounds’ Robert Brown (1814). Grasstrees (arborescent Xanthorrhoea, Dasypogon, Kingia), with their crown of long narrow leaves and blackened leafbase-covered trunk (caudex), are a characteristic growth form in the Australian flora. Xanthorrhoea is the most widespread genus, with 28 species that are prominent from heathlands to sclerophyll forests. While leaf production for X. preissii reaches a peak in spring–summer, growth never stops even in the cool winter or dry autumn seasons. Summer rain, accompanied by a rapid rise in leaf water potential, may be sufficient to stimulate leaf production, whereas root growth is confined to the usual wet season. Grasstrees are highly flammable yet rarely succumb to fire: while retained dead leaves may reach >1000°C during fire, the temperature 100 mm above the stem apex remains <60°C and the roots are insulated completely. Immediately following fire, leaf production from the intact apical meristem is up to six times greater than that at unburnt sites. For X. preissii, pre-fire biomass is restored within 40 weeks; the mass of live leaves remains uniform from thereon, whereas the mass of dead leaves increases steadily. Leaves usually survive for >2 years. In X. preissii, the post-fire growth flush corresponds to a reduction in starch storage by desmium in the caudex. Minerals, especially P, are remobilised from the caudex to the crown following a spring fire, but accumulate there following an autumn fire. At least 80% of P is withdrawn from senescing leaves, while >95% K and Na are leached from dead leaves. Most stored N and S are volatilised by fire, with 1–85% of all minerals returned as ash. Despite monthly clipping for 16 months, X. preissii plants recover, although starch reserves are depleted by 90%, indicating considerable resilience to herbivory. Analysis of colour band patterns in the leafbases of X. preissii shows that elongation of the caudex may vary more than 5–50 mm per annum, with 10–20 mm being typical. Exceptionally tall plants (>3 m) may reach an age of 250 years, with a record at 450 years (6 m). Fires, recorded as black bands on the leafbases, in south-western Australia have been decreasing in frequency but increasing in variability since 1750–1850. Some grasstrees have survived a mean fire interval of 3–4 years over the last two centuries. In more recent times, some grasstrees have not been burnt for >50 years. The band-analysis technique has been used to show a downward trend in plant δ13C of 2–5.5‰ from 1935 to the present. Grasstrees are most likely to flower in the first spring after fire. A single inflorescence is initiated from the apical meristem, elongating at up to 100 mm day–1 and reaching a length up to 3 m, with one recorded at 5.5 m. This rapid rate of elongation is achieved through leaf (and inflorescence) photosynthesis and desmium starch mobilisation. The developing spike and seeds are vulnerable to a moth larva. Leaf production recommences from axillary buds and the trade-off with reproduction is equivalent to 240 leaves in X. preissii. Flowering and seed production are affected by time of fire. Grasstrees are mainly insect-pollinated. Up to 8000 seeds per spike are produced, although pre-dispersal granivory is common. Seeds are released in autumn and persist in the soil for <2 years. Most fresh seeds germinate in the laboratory but germination is inhibited by light. At any time, seedlings and juveniles may account for most plants in the population, although there may be up to an 80% reduction within 1 year of seedling emergence, often due to kangaroo herbivory. In the absence of fire, mortality of adults may be 4% per annum. Although few grasstree species are considered rare or threatened, their conservation requirements, especially in regard to a suitable fire regime, remain unknown. Grasstrees are particularly susceptible to the exotic root pathogen, Phytophthora cinnamomi, although recruitment among some species has been observed 20–30 years after pathogen invasion. Much remains to be known about the biology of this icon of the Australian bush.
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"Phytophthora cinnamomi. [Distribution map]." Distribution Maps of Plant Diseases, n. 6) (1 agosto 1991). http://dx.doi.org/10.1079/dmpd/20046500302.
Testo completoAbstract (sommario):
Abstract A new distribution map is provided for Phytophthora cinnamomi Rands. Hosts: Ananas, Cinchona, Cinnamomum, Castanea, Persea, Pinus, Rhododendron and others. Information is given on the geographical distribution in Africa, Burundi, Cameroon, Congo, Gabon, Guinea, Ivory Coast, Kenya, Morocco, South Africa, Uganda, Zambia, Zimbabwe, Asia, China, Jiangsu, India, Madras, Andhra, Pradesh, West Bengal, Indonesia, Java, Sumatra, Israel, Japan, Malaysia, Peninsular, Sabah, Philippines, Taiwan, Turkey, Vietnam, USSR, Georgia, Australasia & Oceania, Australia, New South Wales, Queensland, Victoria, Western Australia, South Australia, Tasmania, Northern Territory, Cook Island, Fiji, Hawaii, New Zealand, Okinawa, Papua New Guinea, Sumatra, Europe, Azores, Belgium, France, Corsica, Germany, Irish Republic, Italy, Netherlands, Portugal, Spain, Switzerland, UK, USSR, Black Sea Region, Yugoslavia, North America, Canada, British Columbia, Mexico, USA, Central America & West Indies, Barbados, Belize, Costa Rica, Cuba, Dominican Republic, Guatemala, Honduras, Jamaica, Panama, Puerto Rico, Salvador, St Lucia, St Vincent, Trinidad, South America, Argentina, Bolivia, Brazil, Sao Paulo, Brasilia, Chile, Colombia, Guyana, Peru, Venezuela.
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Hunter, Shannon, Rebecca McDougal, Nari Williams e Peter Scott. "Variability in phosphite sensitivity observed within and between seven Phytophthora species". Australasian Plant Pathology, 11 gennaio 2022. http://dx.doi.org/10.1007/s13313-021-00846-5.
Testo completoAbstract (sommario):
AbstractPhosphite is used to control and manage many phytophthora diseases in horticultural systems worldwide and natural ecosystems in Australia, Africa, New Zealand and parts of Northern America and Europe. Phosphite does not kill Phytophthora species, but inhibits growth while also stimulating host defence responses. Phytophthora species differ in their underlying tolerance to phosphite and isolates have been shown to acquire tolerance after prolonged exposure. Intra- and inter-specific variability in phosphite sensitivity is of interest to determine the efficacy and sustainability of phosphite for the treatment of phytophthora diseases, which continue to spread globally. Seven Phytophthora species were tested for their sensitivity to phosphite in vitro in a mycelial growth experiment. Phytophthora agathidicida was the species most sensitive to phosphite, being inhibited by 98.7% on average at the lowest phosphite treatment (15 µg/mL phosphite), followed by P. aleatoria, P. cinnamomi, P. pluvialis, P. multivora, P. kernoviae and P. citricola. Huge intraspecific variability was observed with P. kernoviae, which raises the question of whether diseases caused by P. kernoviae such as phytophthora needle blight of Pinus radiata could be managed effectively with phosphite. Further work is required to determine the phosphite sensitivity of different introduced and native Phytophthora species growing in key hosts and whether tolerance observed in vitro is also expressed in vivo.