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Australia

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Scott P.M.,Murdoch University | Scott P.M.,New Zealand Forest Research Institute | Dell B.,Murdoch University | Shearer B.L.,Murdoch University | And 4 more authors.
Australasian Plant Pathology | Year: 2013

Tree declines are increasingly being reported around the world. Since the 1990's Eucalyptus gomphocephala (tuart) has suffered a significant decline in the Yalgorup region, approximately 100 km south of Perth Western Australia. The complexity of many tree declines makes diagnosis difficult. Robust tools are needed to help identify factors contributing to tree declines. Two experiments tested the effect of trunk applied phosphite, nutrients and combined phosphite and nutrient treatments on wild declining E. gomphocephala. Treatment efficacy was tested as a management option to mitigate crown decline and as an explorative tool to help determine disease causality. Experiment 1 assessed the efficacy of combined treatments of trunk injections of different phosphite concentrations, trunk nutrient implants of different compositions and combined phosphite and nutrient treatments. Experiment 2 assessed the efficacy of different phosphite concentrations. In Experiment 1, phosphite, together with nutrient treatments, increased the average crown condition by 21 %, as measured using a crown health score (CHS) averaged over 4 years, with the greatest improvements evident 6 months after application. Injection of 25 g phosphite/L combined with 0.3 g zinc sulphide gave the greatest increase. In Experiment 2, application of 75 to 375 g phosphite/L increased the CHS compared to the control treatment, with the greatest improvements in trees injected with 150 g phosphite/L. Foliar analysis for Experiment 2 confirmed a significant uptake of phosphite for all phosphite treatments. The increase in the CHS and significant flushes in new growth resulting from phosphite and nutrient treatments highlight the possible involvement of Phytophthora species in the decline, as Phytophthora species are known to be controlled by phosphite application. Further work on combined phosphite and nutrient applications, with a particular emphasis on zinc, is required to help understand and potentially mitigate the E. gomphocephala decline. © 2013 Australasian Plant Pathology Society Inc.


Scott P.M.,Murdoch University | Jung T.,Murdoch University | Shearer B.L.,Murdoch University | Shearer B.L.,Department of Environment and Conservation Perth | And 4 more authors.
Forest Pathology | Year: 2012

Phytophthora multivora is associated with the rhizosphere of declining Eucalyptus gomphocephala, Eucalyptus marginata and Agonis flexuosa. Two pathogenicity experiments were conducted. The first experiment examined the pathogenicity of five P. multivora isolates and one Phytophthora cinnamomi isolate on the root systems of E. gomphocephala and one P. multivora isolate on the root system of E. marginata. In the second experiment, the pathogenicity of P. multivora to E. gomphocephala and E. marginata saplings was measured using under-bark stem inoculation. In Experiment 1, the P. cinnamomi isolate was more aggressive than all P. multivora isolates causing significant loss of fine roots and plant death. Two P. multivora isolates and the P. cinnamomi isolate caused significant losses of E. gomphocephala fine roots 0-2mm in diameter and significantly reduced the surface area of roots 0-1mm in diameter. One P. multivora and the P. cinnamomi isolate significantly reduced the surface area of roots 1-2mm in diameter. Two of the P. multivora isolates significantly reduced the number of E. gomphocephala root tips. In E. marginata, the length and surface area of roots 0-1mm in diameter and number of root tips were significantly reduced by P. multivora infestation. Rhizosphere infestation with the P. multivora isolates and P. cinnamomi isolate on E. gomphocephala, and one P. multivora isolate on E. marginata, did not significantly influence the foliar nutrient concentrations. In Experiment 2, under-bark inoculation with P. multivora caused significant lesion extension in E. gomphocephala and E. marginata saplings, compared to the control. We propose that P. multivora is inciting E. gomphocephala and E. marginata decline by causing fine root loss and subsequently interfering with nutrient cycling throughout the plant. The impact of fine root loss on the physiology of plants in sites infested with P. multivora requires further research. © 2011 Blackwell Verlag GmbH.


Scott P.M.,Murdoch University | Scott P.M.,New Zealand Forest Research Institute | Barber P.A.,Murdoch University | Barber P.A.,Arbor Carbon Pty Ltd | Hardy G.E.S.J.,Murdoch University
Australasian Plant Pathology | Year: 2015

Systemic treatment of stems with injections of phosphite liquid and novel soluble capsule implants of phosphite, PHOSCAP® (phosphorous, potassium, iron, manganese, zinc, boron, copper, magnesium and molybdenum) and MEDICAP MD® (nitrogen, phosphorous, potassium, iron, manganese, and zinc), were applied to Banksia grandis and Eucalyptus marginata trees to control Phytophthora cinnamomi. Four weeks after treatment application, excised branches were under-bark inoculated with P. cinnamomi. In B. grandis, phosphite implants and liquid injections significantly reduced lesion length compared to the control, and MEDICAP MD® implants; however, there was no significant difference in lesion length between trees treated with phosphite implants and liquid injections and PHOSCAP implants. In E. marginata, phosphite implants and liquid injections significantly reduced lesion length compared to the control, PHOSCAP® and MEDICAP MD® implants. In B. grandis and E. marginata, PHOSCAP® and MEDICAP MD® implants reduced the average lesion length compared to the control; however, the interactions were not significant. Results show that both liquid phosphite injections and novel phosphite implants are effective at controlling lesion extension in B. grandis and E. marginata, caused by P. cinnamomi. Further work is required to determine if nutrient application reduces Phytophthora disease through improving plant health. © 2015, Australasian Plant Pathology Society Inc.


Yulia E.,Murdoch University | Yulia E.,Padjadjaran University | Hardy G.E.S.J.,Murdoch University | Barber P.,Murdoch University | And 2 more authors.
Forest Pathology | Year: 2014

A serious canker disease is affecting the health of Corymbia ficifolia in urban areas of Perth, Western Australia. Quambalaria coyrecup was frequently associated with diseased trees and its presence confirmed by morphological characters and DNA sequencing. A number of Quambalaria species have previously been identified as causal agents of canker and shoot blight diseases on a range of Eucalyptus and Corymbia species. It was therefore the aim, using glasshouse studies, to determine whether Q. coyrecup was the primary causal agent of the cankers on C. ficifolia and whether other Quambalaria species could also be associated with the disease. All seedlings inoculated with Q. coyrecup produced canker symptoms within 1 month after inoculation. Canker lesions typical of those observed in the field also occurred in the four subsequent months, after which time the trial was terminated. Inoculation with Q. cyanescens and Q. pitereka (isolated from C. ficifolia shoots) did not result in lesion development. This study establishes that Q. coyrecup is a serious pathogen of C. ficifolia and that wounding is required for canker development to occur. The management of Quambalaria canker must therefore include the minimization of artificial wounding of trees in the nursery and field. © 2014 Blackwell Verlag GmbH.


Barber P.A.,Arbor Carbon Pty Ltd | Barber P.A.,Murdoch University | Crous P.W.,Fungal Biodiversity Center | Crous P.W.,University Utrecht | And 3 more authors.
Persoonia: Molecular Phylogeny and Evolution of Fungi | Year: 2011

The genus Vermisporium presently accommodates 13 species, 11 of which are associated with leaf spots of eucalypts in the Southern Hemisphere. Vermisporium is chiefly distinguished from Seimatosporium (Amphisphaeriaceae) on the basis of a short exogenous basal appendage, and the absence of a recognisable apical appendage. Due to the increasing importance of these species in native forests, and confusion pertaining to their taxonomy, a revision of the genus was undertaken based on fresh collections and dried herbarium specimens. Results from DNA sequence data analyses of the nrDNA-ITS and 28S nrRNA genes for species of Vermisporium indicated the genus to be a synonym of Seimatosporium. New combinations are introduced in Seimatosporium for several species: S. acutum, S. biseptatum, S. brevicentrum, S. obtusum, S. orbiculare, S. verrucisporum and S. walkeri. An updated key to all species occurring on eucalypts is also provided.


Barber P.A.,ArborCarbon Pty. Ltd. | Barber P.A.,Murdoch University | Paap T.,Murdoch University | Burgess T.I.,Murdoch University | And 2 more authors.
Urban Forestry and Urban Greening | Year: 2013

Surveys of dying vegetation within remnant bushland, parks and gardens, and streetscapes throughout the urban forest of Perth and the South-west of Western Australia revealed symptoms typical of those produced by Phytophthora species. A total of nine Phytophthora species, including P. alticola, P. multivora, P. litoralis, P. inundata, P. nicotianae and P. palmivora were isolated. In addition, three previously undescribed species, Phytophthora aff. arenaria, Phytophthora aff. humicola and Phytophthora sp. ohioensis were isolated. Isolates were recovered from a wide range of native and non-native host genera, including Agonis, Allocasuarina, Brachychiton, Calothamnus, Casuarina, Corymbia, Dracaena, Eucalyptus, Ficus, Pyrus and Xanthorrhoea. Phytophthora multivora was the most commonly isolated species. Out of 230 samples collected 69 were found to be infected with Phytophthora. Of those 69, 54% were located within parks and gardens, 36% within remnant bushland, and 10% within streetscapes. These pathogens may play a key role in the premature decline in health of the urban forest throughout Perth, and should be managed according to the precautionary principle and given high priority when considering future sustainable management strategies. © 2013.


Ishaq L.,Murdoch University | Barber P.A.,Murdoch University | Barber P.A.,Arbor Carbon Pty Ltd | Hardy G.E.S.J.,Murdoch University | And 2 more authors.
Mycorrhiza | Year: 2013

The health of Eucalyptus gomphocephala is declining within its natural range in south-western Australia. In a pilot study to assess whether changes in mycorrhizal fungi and soil chemistry might be associated with E. gomphocephala decline, we set up a containerized bioassay experiment with E. gomphocephala as the trap plant using intact soil cores collected from 12 sites with E. gomphocephala canopy condition ranging from healthy to declining. Adjacent soil samples were collected for chemical analysis. The type of mycorrhiza (arbuscular or ectomycorrhizal) formed in containerized seedlings predicted the canopy condition of E. gomphocephala at the sites where the cores were taken. Ectomycorrhizal fungi colonization was higher in seedling roots in soil taken from sites with healthy canopies, whereas colonization by arbuscular mycorrhizal fungi dominated in roots in soil taken from sites with declining canopies. Furthermore, several soil chemical properties predicted canopy condition and the type of mycorrhizal fungi colonizing roots. These preliminary findings suggest that large-scale studies should be undertaken in the field to quantify those ectomycorrhiza (ECM) fungi sensitive to E. gomphocephala canopy decline and whether particular ECM fungi are bioindicators of ecosystem health. © 2013 Springer-Verlag Berlin Heidelberg.


PubMed | Arbor Carbon Pty Ltd.
Type: | Journal: Persoonia | Year: 2012

The genus Vermisporium presently accommodates 13 species, 11 of which are associated with leaf spots of eucalypts in the Southern Hemisphere. Vermisporium is chiefly distinguished from Seimatosporium (Amphisphaeriaceae) on the basis of a short exogenous basal appendage, and the absence of a recognisable apical appendage. Due to the increasing importance of these species in native forests, and confusion pertaining to their taxonomy, a revision of the genus was undertaken based on fresh collections and dried herbarium specimens. Results from DNA sequence data analyses of the nrDNA-ITS and 28S nrRNA genes for species of Vermisporium indicated the genus to be a synonym of Seimatosporium. New combinations are introduced in Seimatosporium for several species: S. acutum, S. biseptatum, S. brevicentrum, S. obtusum, S. orbiculare, S. verrucisporum and S. walkeri. An updated key to all species occurring on eucalypts is also provided.

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