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Australian native plant susceptibility to Phytophthora ramorum

Ireland, K., Hüberli, D., Dell, B., Smith, I., Rizzo, D., Kriticos, D. and Hardy, G.E.St.J. (2010) Australian native plant susceptibility to Phytophthora ramorum. In: Plant Health & Protection Research Symposium, 29 October, Perth, Western Australia.


Phytophthora ramorum causes considerable and widespread damage in nurseries, gardens and natural woodland ecosystems of the USA and Europe, and is classified as a Category 1 plant pest in Australia. It is of particular interest to Australian plant biosecurity as, like P. cinnamomi, it has the potential to become a major economic and ecological threat in areas with susceptible hosts and conducive climates. Research was undertaken in California to assess the pathogenicity of P. ramorum on Australian native plants. Sixty-nine plant species within 24 families were sourced from established gardens and arboretums, and selected based upon provenance from areas of climatic suitability for P. ramorum as well as ecological and economical importance. Foliar, branch and log susceptibility were tested using detached leaf, branch and log inoculations. Sporulation potential and chlamydospore production was also tested on detached foliage of a select mid to upper storey species. Potentially highly susceptible foliar Australian host species included Eucalyptus regnans, Isopogon cuneatus, I. formosus, Leptospermum scoparium, L. lanigerum, and Melaleuca squamea, while potentially resistant hosts included Hedycarya angustifolia, Olearia argophylla, Phyllocladus aspleniifolius, Pittosporum undulatum, and Podocarpus lawrencei. Disease incidence and severity were greater during the summer, and when the leaves were wounded. Putative sporulating hosts included Agonis flexuosa, C. ficifolia, Eucalyptus delegatensis, and E. viminalis. Highly susceptible branch hosts included E. nitens, E. sideroxylon, E. viminalis, Hardenbergia violaceae, I. formosus and N. cunninghamii, and potential bole canker hosts included E. delegatensis and E. regnans. A simulation model developed using CLIMEX suggests a high likelihood of potential distribution in Australia along coastal NSW, and in cooler, wetter regions of Victoria and Tasmania. These results extend the known potential host range for P. ramorum, confirming it as a potential threat to Australian plant industries and ecosystems, and highlighting additional potential hosts prevalent in global horticultural trade. Results of the studies will be discussed in relation to their implications for disease entry, spread and development of an epiphytotic within an Australian biosecurity framework.

Item Type: Conference Item
Murdoch Affiliation(s): Centre for Phytophthora Science and Management
School of Biological Sciences and Biotechnology
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