Austropuccinia psidii (myrtle rust) has long been considered a significant threat to Australian plant industries and ecosystems. The rust was first detected in Australia in April 2010 on the central coast of New South Wales and has continued to spread with detections extending from Tasmania in the south, Cape York Peninsula in the north east, and west to Arnhem Land in the Northern Territory. The current host range in Australia includes >350 species from 57 genera. Austropuccinia psidii severely affects key species in natural ecosystems, with localised extinctions recorded (Rhodomyrtus psidioides and Rhodamnia rubescens) and with many species no longer ecologically functional. Our studies have demonstrated severe impacts of myrtle rust on native plant communities. Austropuccinia psidii has caused significant disturbance in lowland subtropical rainforest and wet sclerophyll environments where Myrtaceae dominate the rainforest understorey. Similar impacts have been recorded in coastal heath environments affected by wildfire (Melaleuca nodosa, Leptospermum spp.) with severe decline in once dominant species and little evidence of regeneration potential. Keystone species such as Melaleuca quinquenervia are also being impacted, with tree deaths and reduced flowering rates recorded. Future research programs are required to identify and monitor species and plant communities at greatest risk of decline. The implementation of a disease screening and tree breeding program may be required for some species as without intervention, regaining lost genetic diversity within these populations may not be possible. The rate of decline of some species is alarming and retaining viable germplasm for conservation purposes is essential.

Phytophthora dieback caused by P. cinnamomi has been identified as a key threatening process under the Commonwealth’s Environment Protection and Biodiversity Conservation Act 1999. A new threat abatement plan has been made to help guide mitigation of the impacts of dieback specifically on listed threatened species and ecological communities but on native species and communities more broadly. We present the key elements of the plan including strategies to prevent Phytophthora from spreading into areas that are free of the disease, strategies to reduce the impacts in infested areas, recovery actions for the conservation of biodiversity assets being impacted, and research actions towards mitigating the impacts. The threat abatement plan provides a means for researchers and land managers to understand how their work fits into the identified national actions and through the informal implementation group a means for effective coordination, information exchange and collation of the action by people and groups across Australia.

Prevention is an important strategy in the management of Phytophthora dieback. The key challenge is for everyone to always clean their footwear, equipment and vehicles when entering and / or leaving susceptible areas. This involves changing current human behaviours and encouraging the adoption of new behaviours. Providing information through educational campaigns is an important first step for increasing awareness and shifting attitudes. But contemporary behaviour change literature shows that providing information by itself is seldom enough to change behaviour. A successful behaviour change intervention needs to consider all the factors, not just awareness and knowledge, which promote or impede the required actions. Understanding the capabilities, opportunities and motivations of your target audience is a crucial step in developing more effective interventions.
This talk will examine how to design appropriate interventions, using an integrative framework developed from the behaviour change literature. Examples from current research projects, covering a range of biosecurity issues, will be used to illustrate the process. Our research results emphasise the value of adopting approaches incorporating human behaviour and persuasive communication theory to improve the effectiveness of management interventions.

The dominant keystone species Macquarie cushion (Azorella macquariensis, Apiaceae) has undergone rapid, wide-spread dieback across the alpine plateau of Macquarie Island, potentially signalling the initiation of a regime shift. To date the pathogen/s have not been identified, however, a number of fungal, bacterial and oomycete taxa were found in association with cushion dieback. It was hypothesised that a decadal reduction in plant available water caused by change in regional climate, facilitated the secondary pathogenic infection of weakened cushions. This suggested that dieback would be greatest under high water-stress. While previous topographic modelling demonstrated a negative latitudinal gradient in dieback, terrain variables that influence water availability had no effect on the amount of dieback. Using fine-scale microclimate data we found that dieback was driven by microclimate extremes known to promote (humidity) or suppress (freezing) pathogen activity, in particular fungal or water-mould pathogens. While variables associated with water stress (VPD, wind exposure, and soil gravel content) were unimportant. To improve future monitoring and understanding we developed refined condition classes. The classes revealed a latitudinal progression in dieback, where the healthiest cushions occurred in the south and the most advanced dieback in the north. The south of the island was significantly colder, while relative humidity was similar across regions, suggesting that freezing days drive the latitudinal gradient of dieback. Microclimate and refined condition classes provided valuable insights into the drivers and progression of cushion dieback on Macquarie Island, emphasising their importance for inclusion within future monitoring programs to assess ecosystem change.

The Australian host list for the invasive Myrtle Rust pathogen (Austropuccinia psidii) stands at just under 400 Myrtaceae species. A 2018 review nominates 45 native taxa known or suspected to be undergoing serious decline, or at very high risk. Some keystone species are highly susceptible. Ecosystem declines and species extinctions are to be expected. Many of the most susceptible hosts are exposed to airborne spores over their total range, with no refugia. For some, the rate of decline is likely to outstrip the natural selection and dispersal of any disease-resistant genotypes, and niche closure aggravates the problem. Other species will decline more slowly. Further strains of the pathogen, including strongly eucalypt-associated variants, pose a continuing biosecurity risk.
A conservation response is feasible, but requires a level of coordination and investment rarely seen for environmental threats (although common for agricultural pathogens). Such a response is taking shape in New Zealand but not in Australia. Here, it would involve uncomfortably interventionist approaches for a number of species. Enhancement of natural populations with rust-tolerant natural genotypes or selectively-bred traits is feasible, for those species that have them. Where resistance is altogether lacking, inter-species trait transfer may be the only option. The ecological, social, and technical issues are formidable, but not insoluble. For the most at-risk species, preservation of any options requires urgent field survey, representative germplasm capture, and seed storage enablement research, as first steps. A draft Action Plan released in 2018 provides a framework for a national response.

The development of a State Phytophthora Dieback Management and Investment Framework (Framework), that identifies and ranks the top 100 Priority Protection Areas (PPAs), provides the first true landscape scale strategic/tactical plan for ongoing disease management in Western Australia. The Framework identifies the most significant examples of ecosystems of plant species and communities that are vulnerable to Phytophthora Dieback that should be protected and conserved over the next 50 years.

The Framework was developed through a multi-criteria prioritisation process, utilising GIS modelling, state wide datasets and expert weightings. It has provided a blueprint for collaborative Phytophthora Dieback management across tenure, with a common set of tools and protocols. This has been implemented through a cohesive decision making approach that includes on-ground actions, planning, engagement and behaviour change and structured training.

Three phases define the development of the Framework; identify, prioritise and implementation. South Coast NRM has over the last decade developed, in partnership with land managers and research institutions, a range of practical tools, online resources and process for the practical application of a science based approach to Phytophthora Dieback management across tenure.

The Framework provides a logical process and operational toolkit to plan collaborative, area-specific management actions and investment strategies required to protect PPAs against the adverse impacts of Phytophthora Dieback at a landscape scale. It is also a process that has broader application for managing biosecurity risks in both the environmental and agricultural sectors.

The outstanding universal value for which the Wet Tropics World Heritage Area is recognised lies not just in the number of plant species and high degree of endemicity, but in the evolutionary diversity these species represent. The presence of Phytophthora cinnamomi in the region has been known for some decades, where it is associated with patch death in notophyll vine forests, usually at mid to high altitudes on acid volcanic soils. A monitoring program instituted in the late 1990s mapped patch-death in tropical forests, assessed tree health of hundreds of canopy tree species, and recorded species-specific impacts. Several Phytophthora species were identified from both inside and outside patch-death sites. Monitoring ceased in 2004, however, there has been ongoing reports of patch death within upland forests of the Wet Tropics, including observations by the authors. With the finalisation of the Threat Abatement Plan, the issue of Phytophthora management in the Wet Tropics has once again been brought forward. The authors will discuss the re-establishment of the monitoring program within the Wet Tropics. The program will revisit monitoring sites to assess tree health and will compare impacts on individual species over the fifteen year period. Monitoring outcomes will enable us to assess site recovery, changes in species composition, and consider the question – is the threat posed by Phytophthora cinnamomi to biodiversity in the forests of Wet Tropics as great as that seen in southern Australia?

Due to the amphibian fungal parasite chytridiomycosis, the past half-century have seen the global decline of at least 501 amphibian species including 90 presumed extinctions. With the risk of potential outbreaks in new areas, chytrid fungus (Batrachochytrium dendrobatidis) poses an ongoing threat to amphibians.

While substantial research has focused on mitigating this disease, there are currently no feasible management solutions. Biological interactions can play a key role in mitigating chytrid fungus but have not been adequately assessed. The aquatic crustacean Daphnia, for example, can reduce amphibian infection rates by preying on chytrid fungus zoospores in the water column. Daphnia are also preyed upon by the introduced eastern mosquitofish, Gambusia holbrooki, such that where these invasive fish occur in Australia, Daphnia are often absent. As such, the invasion of the eastern mosquitofish may have indirectly increased chytrid fungus infection rates in amphibians by eliminating Daphnia. Our research investigated this possibility in the presence and absence of vegetation.

We conducted this research in 2L microcosms inoculated with chytrid fungus containing either the eastern mosquitofish, Daphnia carinata, both species, and neither species in the presence and absence of vegetation. These experiments informed us whether Daphnia is an effective biological control of chytrid fungus. Likewise, whether aquatic vegetation can provide refuges for Daphnia in the presence of the eastern mosquitofish. By examining the impacts a species interaction has on chytrid fungus, our research can improve on-ground management methods being employed to mitigate this pathogen.

Phytophthora cinnamomi is an introduced soil-borne plant pathogen to Australia, where in the south-west of Western Australia alone, it can kill over 41% of the 5710 described plant species. This region is one of the world’s 25 original Biodiversity Hotspots. As a consequence of its introduction, it has changed plant species richness and diversity in susceptible plant communities and in turn impacted on vertebrate and invertebrate fauna that depend on plants for food, shelter and refugia. Once impacted, susceptible plant species disappear and as the pathogen can persist on tolerant plant species, it will never disappear from a site. As a result, many plant species can become locally or regionally extinct. These sites cannot be rehabilitated. The capability for Phytophthora dieback to destroy millions of hectares of diverse plant communities is alarming. The 1999 Environment Protection and Biodiversity Conservation Act lists P. cinnamomi as a ‘Key Threatening process to Australia’s Biodiversity’. This talk will cover the ecology and pathology of the pathogen, how it is spread, and its impact on susceptible plant species and communities and the biodiversity assets they support. The strengths and weaknesses of current control methods and the challenges faced by managers to engage with the wider community to prevent its spread and subsequent impact on disease-free plant communities will be covered. Approaches to remediate impacted sites to provide ecological services similar to those prior to the introduction of the pathogen will also be discussed.

The Tasmanian Forest Practices system was set up during the 1980s. It is designed to ensure protection is provided for the natural and cultural values of the forest when forest practices are carried out. The Forest Practices Code is supported by many detailed documents; Flora Technical Note 8 deals specifically with the management of Phytophthora cinnamomi in production forests. It specifies when “clean” gravel must be used, identifies the indicator/host species for P. cinnamomi and therefore the native vegetation communities at risk.
Forestry Tasmania (FT), the government forestry organisation at that time, with > 130 quarries on state-managed forest, was eager to comply with the Code but had a fundamental question… How do we know if our quarries are clean?
The Pathologist with FT developed a field survey to be applied to all active quarries. As well as recognition of P. cinnamomi symptoms, he identified the risk factors for P. cinnamomi spread; substrate, forest type, altitude, overburden management and drainage, and these are addressed in a 2-pager inspection report. A risk matrix determines the expiry date of the information in the report.
Other forest companies are required to comply with the Code, and FT started conducting quarry inspections on a fee-for-service basis. Civil construction companies, windfarms and infrastructure managers also had customers demanding clean gravel. Slowly the “quick and dirty” FT inspection became, by default, the industry standard.
The P. cinnamomi inspection of private quarries is customer driven, and is not required by the State quarry regulators, so it currently occurs in a sporadic and ad hoc manner across Tasmania.