02169nas a2200253 4500008004100000022001400041245013800055210006900193260002900262300001400291490000700305520136800312653002201680653001301702653002701715653002101742100001701763700001601780700001201796700001501808700001501823700002201838856005501860 2012 eng d a1365-305900aPotential susceptibility of Australian native plant species to branch dieback and bole canker diseases caused by Phytophthora ramorum0 aPotential susceptibility of Australian native plant species to b bBlackwell Publishing Ltd a234–2460 v613 a

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.

10ainvasive organism10aoomycete10aramorum branch dieback10aSudden oak death1 aIreland, K B1 aHüberli, D1 aDell, B1 aSmith, I W1 aRizzo, D M1 aHardy, St., G E J uhttp://dx.doi.org/10.1111/j.1365-3059.2011.02513.x02306nas a2200205 4500008004100000022001400041245012500055210006900180260002900249300001400278490000700292520164900299100001701948700001601965700001201981700001501993700001502008700002202023856005502045 2011 eng d a1439-032900aPotential susceptibility of Australian flora to a NA2 isolate of Phytophthora ramorum and pathogen sporulation potential0 aPotential susceptibility of Australian flora to a NA2 isolate of bBlackwell Publishing Ltd a305–3200 v423 a

Phytophthora ramorum is an invasive plant pathogen and the cause of considerable and widespread damage in nurseries, gardens and natural woodland ecosystems of the USA and Europe. It is considered to be a significant plant disease as it could cause biodiversity loss and severe economic losses in plant industries in areas where it is not yet known to exist, such as Australasia. Foliar susceptibility and sporulation potential were tested using detached-leaf assays for 70 Australian native plant species sourced from established gardens and arboreta in California using a NA2 isolate of P. ramorum. Correa ’Sister Dawn’, Eucalyptus regnans, Isopogon cuneatus, I. formosus, Leptospermum scoparium, L. lanigerum and Melaleuca squamea were identified as potentially highly susceptible host species. Hedycarya angustifolia, Olearia argophylla, Phyllocladus aspleniifolius, Pittosporum undulatum and Podocarpus lawrencei were identified as potentially resistant. All 70 species were able to be infected with P. ramorum, as confirmed by reisolation. Putative sporulating hosts include five members of the Myrtaceae, Agonis flexuosa, Corymbia ficifolia, Eucalyptus haemastoma, E. delegatensis and E. viminalis. As a part of a precautionary strategy, the potentially highly susceptible species found in this study are suitable candidates for targeted surveillance programmes in high-risk incursion areas of Australia and within the global horticultural trade.

1 aIreland, K B1 aHüberli, D1 aDell, B1 aSmith, I W1 aRizzo, D M1 aHardy, St., G E J uhttp://dx.doi.org/10.1111/j.1439-0329.2011.00755.x