Myrtle Rust reviewed The impacts of the invasive plant pathogen Austropuccinia psidii on the Australian environment R. O. Makinson 2018 DRAFT CRCPLANTbiosecurity CRCPLANTbiosecurity © Plant Biosecurity Cooperative Research Centre, 2018 ‘Myrtle Rust reviewed: the impacts of the invasive pathogen Austropuccinia psidii on the Australian environment’ is licenced by the Plant Biosecurity Cooperative Research Centre for use under a Creative Commons Attribution 4.0 Australia licence. For licence conditions see: https://creativecommons.org/licenses/by/4.0/ This Review provides background for the public consultation document ‘Myrtle Rust in Australia – a draft Action Plan’ available at www.apbsf.org.au Author contact details R.O. Makinson1,2 [email protected] 1Bob Makinson Consulting ABN 67 656 298 911 2The Australian Network for Plant Conservation Inc. Cite this publication as: Makinson RO (2018) Myrtle Rust reviewed: the impacts of the invasive pathogen Austropuccinia psidii on the Australian environment. Plant Biosecurity Cooperative Research Centre, Canberra. Front cover: Top: Spotted Gum (Corymbia maculata) infected with Myrtle Rust in glasshouse screening program, Geoff Pegg. Bottom: Melaleuca quinquenervia infected with Myrtle Rust, north-east NSW, Peter Entwistle This project was jointly funded through the Plant Biosecurity Cooperative Research Centre and the Australian Government’s National Environmental Science Program. The Plant Biosecurity CRC is established and supported under the Australian Government Cooperative Research Centres Program. EXECUTIVE SUMMARY This review of the environmental impacts of Myrtle Rust in Australia is accompanied by an adjunct document, Myrtle Rust in Australia – a draft Action Plan. The Action Plan was developed in 2018 in consultation with experts, stakeholders and the public. The intent of the draft Action Plan is to provide a guiding framework for a specifically environmental dimension to Australia’s response to Myrtle Rust – that is, the conservation of native biodiversity at risk. An environmental response plan has been largely lacking up to now. The proposed actions aim to: • anticipate and minimise decline of native species and ecosystems at risk from this pathogen; • prevent the total extinction of high-risk species; • maximise the options for future recovery for at least some affected species and ecosystems. The intent of this review of impacts is to provide the evidentiary basis for the proposed actions, by: • synthesising information on Myrtle Rust and its effects, much of it previously unpublished or only available in specialist journals, in a form relevant and accessible to all key stakeholders; • describing the risks to Australia’s natural, social and economic assets posed by Myrtle Rust; • describing meaningful conservation actions that can be taken now and in the future; • outlining the technical basis for potential recovery actions for some species and ecosystems; • showing that a coordinated environmental response to Myrtle Rust will serve Australia’s future environmental biosecurity interests. Myrtle Rust is an introduced and highly invasive fungal disease of plants. It is of South American origin. First detected in Australia in 2010, it has established along the entire mainland eastern seaboard, in parts of the Northern Territory, and marginally in parts of Tasmania and Victoria. It is not yet present in South Australia or Western Australia. Myrtle Rust has already proved capable of infecting 358 native species or subspecies, in screening tests and/or in the field. This ‘host range’ will increase as new hosts are detected and as the pathogen spreads to new areas. Only about 3% of species tested have failed to become infected. Myrtle Rust affects only the plant family Myrtaceae, which makes up 10% of Australia’s native flora and includes eucalypts, tea-trees, paperbarks, and lillypillies. Myrtle Rust can be managed in horticultural production systems, but is not amenable to direct management at this time in the wild. The Myrtle Rust pathogen favours moist habitats and is unlikely to be a threat in drier areas. It is not a direct threat to human or animal health. However, loss of species, and resulting ecological change and loss of habitat, are likely to threaten some associated animal and plant species, and human social, cultural and economic values and assets. Myrtle Rust has also arrived in recent years in New Zealand, New Caledonia, and South-east Asia. This pathogen is internationally recognised as a global biosecurity problem for natural environments containing the Myrtaceae family, and for industries dependent on it. Australia and its region so far have only one strain of this pathogen. Other strains are known, which would add to the threat. Their continued exclusion from Australia and its surrounds is a national and regional biosecurity priority. The most serious species declines so far, are in north-eastern New South Wales, south-east Queensland, and the Queensland Wet Tropics. Several World Heritage Areas are affected. Myrtle Rust has an uncertain potential to cause damage to native flora in the monsoon tropics. Myrtle Rust Impacts Review June 2018 3 Myrtle Rust has potential to cause serious damage in the south-west of Western Australia if it arrives there and finds the climate suitable for establishment (as predicted by several research studies). The far south-west of WA contains some 40% of Australia’s myrtaceous species. Continued exclusion of the pathogen from South Australia and Western Australia should be a domestic biosecurity priority. 83 of the 358 known host species were listed as ‘threatened’ or ‘near threatened’ in one or more Australian jurisdictions even before the arrival of Myrtle Rust, but most hosts were not previously listed, and some of those now in steepest decline were formerly widespread. An estimated 45 species are known or suspected to be already in decline. These species are recommended in this review and the draft Action Plan for urgent conservation action – four on an emergency basis, 12 as high priority, and 29 as medium priority (end-2020). Some are likely to become extinct in the wild in the near future. The recommended priority actions are for: • field survey to determine decline, and enable further prioritisation and damage assessment; • identification of potentially resistant populations and genotypes in the field; • capture of the widest possible range of plant ‘germplasm’ (seed banking or tissue banking) to conserve genetic diversity and to allow research directed at the eventual use of resistant genotypes to reinforce declining natural populations. A further six species not yet in decline, from two World Heritage Areas, are recommended for precautionary seed or tissue banking. Native species vary in their vulnerability to Myrtle Rust, although the research base is narrow and there are many unknowns. Rust-resistant eucalypts have been successfully bred in South America. Genotypes resistant to Myrtle Rust are known or suspected in some Australian host species, perhaps many. This provides a basis for research directed at the eventual recovery of many species of environmental and economic importance. Also recommended in this review and the adjunct draft Action Plan are research programs into: • the impact of Myrtle Rust on key ecosystems (rainforests, coastal heathlands, and paperbark wetlands); • seed storage techniques for rainforest species not amenable to normal seed banking; • the genetics and physiology of Myrtle Rust infection, and the potential for resistance trait transfer and selective plant breeding. These research programs will both guide future prioritisation of investment, and allow anticipation of ecological and social, cultural and economic effects of the disease. Further recommended actions relate to coordination of a national response, information assembly, social consultation, Indigenous cultural impacts, and information management. These recommendations are contingent on the first overarching recommendation of the draft Action Plan: to establish momentum, funding and leadership for a coordinated national environmental response to Myrtle Rust. No national plan currently exists. No equivalent to the industry levies that help to fund responses to agricultural pathogens, exist for the environmental management sector. The national response to Myrtle Rust to date has been largely led by primary industry agencies and research bodies. As the pathogen takes hold, a specifically environmental response is now an urgent necessity, for biodiversity conservation and the safeguarding of Australia’s natural heritage assets. A strong environmental response to Myrtle Rust will also leave us better prepared for other broad- spectrum environmental pathogens likely to arrive in Australia in the future. Myrtle Rust Impacts Review June 2018 4 Table of Contents EXECUTIVE SUMMARY ............................................................................................................................ 3 INTRODUCTION ....................................................................................................................................... 9 Myrtle Rust – the ‘third bell’ for broad-spectrum pathogens of native biodiversity ....................... 11 On the plant family Myrtaceae – environmental and economic significance: ................................. 13 2010 – The arrival of Myrtle Rust ..................................................................................................... 13 Species declines due