Potential susceptibility of Australian native plant species to branch dieback and bole canker diseases caused by Phytophthora ramorum

Authors

  • K. B. Ireland,

    Corresponding author
    1. Cooperative Research Centre for National Plant Biosecurity, PO Box 5012, Bruce 2617, ACT
    2. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, South St, Murdoch 6150, WA
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  • D. Hüberli,

    1. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, South St, Murdoch 6150, WA
    2. Crop Protection, Department of Agriculture and Food, Western Australia, 3 Baron-Hay Court, South Perth 6151, WA
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  • B. Dell,

    1. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, South St, Murdoch 6150, WA
    2. Sustainable Ecosystems Research Institute, Murdoch University, Murdoch 6150, WA
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  • I. W. Smith,

    1. Department of Forest and Ecosystem Science, University of Melbourne, 500 Yarra Boulevard, Richmond 3121, Vic., Australia
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  • D. M. Rizzo,

    1. Department of Plant Pathology, University of California, 1 Shields Avenue, Davis 95616, CA, USA
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  • G. E. St. J. Hardy

    1. Cooperative Research Centre for National Plant Biosecurity, PO Box 5012, Bruce 2617, ACT
    2. Centre for Phytophthora Science and Management, School of Biological Sciences and Biotechnology, Murdoch University, South St, Murdoch 6150, WA
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E-mail: k.b.ireland@gmail.com

Abstract

Susceptibility to branch dieback caused by Phytophthora ramorum was tested using a detached branch assay for 66 Australian native plant species sourced from established gardens and arboreta in California. Six of these species were further tested for their susceptibility to bole cankers caused by P. ramorum using a sealed log assay. Isopogon formosus and Eucalyptus denticulata were identified as potentially highly susceptible Australian branch dieback hosts. Thirteen potentially tolerant Australian host species included Banksia attenuata, B. marginata, E. haemastoma, E. regnans, Pittosporum undulatum and Billardiera heterophylla. Eucalyptus regnans was identified as a potentially highly susceptible bole canker host, while E. diversicolor and E. viminalis were considered potentially tolerant species to bole cankers caused by P. ramorum. Phytophthora ramorum was able to infect all 66 species, as confirmed by reisolation. These results extend the known potential host range for P. ramorum, confirm it as a possible threat to Australian plant industries and ecosystems and highlight additional associated hosts that are important in the global horticultural trade, native forests and plantation forestry.

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