Invasive pests and pathogens can have devastating and unpredicted impacts on native ecosystems. The threat that Puccinia psidii (myrtle/eucalyptus/guava rust) posed to Australian industries was well recognised, but until its introduction in 2010, there was scant consideration of the impacts this disease may have on endemic Myrtaceous plant species and associated communities in native environments. Since its detection in Australia, the distribution and host range of P. psidii has rapidly expanded and entire species and plant communities are now under threat. The research being undertaken into myrtle rust has enabled improved species selection for production and retail nurseries, and for urban tree planting.

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Managing myrtle rust in Australia
Dr Geoff Pegg
Forest Health Team Leader
Forestry Science
DAF Queensland
Plant Biosecurity Cooperative Research Centre

2. New South
Wales
Queensland
South Australia
Western Australia
Northern
Territory
Tasmania
Spread in Australia
Lord Howe Island
October 2016

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 Screening methodologies for:
- Selecting resistance to Puccinia psidii
 within genera and species
 within breeding populations
- Examining resistance patterns, heritability and resistance
mechanisms
 Field assessment methodologies for:
- Rating susceptibility of Myrtaceae to Puccinia psidii
- Studying impact of Puccinia psidii on species and plant
communities
Myrtle rust research outputs

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 Interstate trade restrictions
- loss of markets or increased treatment requirements
 Species removed from production
 Forestry – minimal direct impact
- Restrictions on movement of germplasm for commercial development (e.g.
Eucalyptus globulus)
 Native foods
- Significant reduction in productivity
- Loss of organic status and related markets
- Relocation of industry
Impact on plant industries

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 Host list and susceptibility rating identifying:
- Resistant/tolerant species for future commercial development
- Highly/extremely susceptible species from an environmental perspective
 Full host list on-line and susceptibility ratings published
- >350 species from 57 genera
 Giblin FR & Carnegie AJ (2014) Puccinia psidii (myrtle rust) - Australian host list.
http://www.anpc.asn.au/myrtle-rust
 Pegg GS, Giblin FR, McTaggart AR, Guymer GP, Taylor H, Ireland KB, Shivas RG, Perry S (2014) Puccinia
psidii in Queensland, Australia: disease symptoms, distribution and impact. Plant Pathology 63, 1005–
102
- Proposed industry publications
 Publication in Horticulture journal and industry magazine articles - April 2017
Myrtle rust research outcomes – Plant industries

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 Simple field rating system
- 180 species assessed
 50 Species HS/ES
 Variability in some species
 Predicting impact
- All trees rated as HS/ES are in
severe decline
 Assessment system to be
adopted for all new host
species reports
Tolerant Moderate
Susceptibility
High
Susceptibility
Extreme
Susceptibility

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 Identification of resistance for implementation into current and
future breeding programs
- Eucalypt species
 Pegg, G. S., Brawner, J. T., and Lee, D. J. 2014. Screening Corymbia populations for resistance to Puccinia psidii Plant Pathology 63: 425-
436.
 Lee, David, Brawner, Jeremy, and Pegg, Geoff 2014. Screening Eucalyptus cloeziana and E. argophloia populations for resistance to
Puccinia psidii. Plant Disease 99, 71-79.
 Butler J. B., Freeman J. S., Vaillancourt R. E., Potts B. M., Glen M., Lee D. J., Pegg G. S. 2016. Evidence for different QTL underlying the
immune and hypersensitive responses of Eucalyptus globulus to the rust pathogen Puccinia psidii Tree Genetics & Genomes 12(3).
- Lemon myrtle
 RIRDC project – 392 clones screened
- D. Lee, J. Doran, G. Pegg, D. Lea, P. Macdonell and F. Giblin 2015. Myrtle Rust Screening in Lemon Myrtle Provenance
Plantings. RIRDC Publication
 PhD student (Emily Lancaster - QAFFI) Examining disease epidemiology, field tolerance and management
options
- Broad leaved Melaleuca species
Myrtle rust research outcomes – plant industries

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Melaleuca quinquenervia provenance
susceptibility

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Melaleuca leucadendra provenance
susceptibility

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Melaleuca viridiflora provenance
susceptibility

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 Susceptibility and impact levels recorded for 180 species
 Detailed assessments on impact for 21 species
- Impact across host natural distribution
- Impact on regeneration
- Impact on plant communities
Myrtle rust research outcomes - Environment

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Impact on widespread species
• Myrtle rust impact
• Most populations consist entirely of
dead or dying trees
• Regenerating seedlings/suckers also
infected & killed
• Rhodomyrtus psidioides
• Native guava
• Conservation status
• Least Concern
• Fast growing
• Important successional role in
rainforest regeneration
Carnegie AJ, Kathuria A, Pegg GS, Entwistle P, Nagel M, Giblin
FR, 2015. Environmental impact of the invasive rust Puccinia
psidii on Australian native Myrtaceae. Biological Invasions DOI
10.1007/s10530-015-0996-y

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Rhodomyrtus psidioides 2014

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Rhodomyrtus psidioides 2016

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Widespread species – Rhodamnia rubescens
2014
2016

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Impact on plant communities – Wet sclerophyll with rainforest understory
Tree species % tree canopy healthy
Acmena smithii 78.5 ±13.124 a
Archirhodomyrtus beckleri 7.66 ±3.063 b
Decaspermum humile 0 ± 0 b
Gossia hillii 4.348 ±4.348 b
Impact of Puccinia psidii infection
– mid-storey
66%
13%
12%
6%
3%
Regenerating seedlings - species composition
Acmena smithii
Archirhodomyrtus beckleri
Rhodamnia maideniana
Decaspermum humile
Gossia hillii
41%
25%
15%
11%
2%
2% 2%
1% 1%
Midstorey species and composition
Archirhodomyrtus beckleri
Gossia hillii
Decaspermum humile
Acmena smithii
Rhodamnia rubescens
Rhodomyrtus psidioides
Syzygium hodgkinsonii
Pilidiostigma glabrum
Syzygium oleosum

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Tallebudgera Valley 2014
Decaspermum humile
Syzygium
corynanthum
Acmena smithii

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Tallebudgera Valley 2016
Decaspermum humile
Syzygium corynanthum
Acmena smithii

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Impact on plant communities
Acmena smithiiAcmena smithii
Decaspermum humile
Acmena smithii
Rhodamnia rubescens

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Impact on plant communities

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 Publication:
- Angus J. Carnegie, Amrit Kathuria, Geoff S. Pegg, Peter Entwistle, Matthew Nagel, Fiona Giblin, 2015.
Environmental impact of the invasive rust Puccinia psidii on Australian native Myrtaceae. Biological
Invasions DOI 10.1007/s10530-015-0996-y –
 Proposed publications - 2017
- Impact of Puccinia psidii on regeneration of Melaleuca quinquenervia and interaction with native
insect pests
- Impact of Puccinia psidii on Myrtaceous rich plant communities in wet sclerophyll environments
in south-east Queensland
- Impact of Puccinia psidii on regeneration of Myrtaceae in coastal heath following wildfires
 Workshop Brisbane April 2016
- Aimed at raising the awareness of myrtle rust within the various environment departments
 Federal and State Environment Departments, PHA, PBCRC etc.
 NZ and USA representatives
 National Environmental Science Program (NESP)
Myrtle rust research outcomes - Environment

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 Legislative outcomes
- Myrtle rust declared as a Threatening Process in NSW and applications submitted for national listing
- Application for Rhodomyrtus psidioides and Rhodamnia rubescens to be listed as Critically Endangered submitted
 Myrtle Rust Environmental Impacts Working Group
 Briefing of Federal Department of Environment Division Heads and Head of
Australian Environment Agencies
- Recommended that issue be taken to a future COAG meeting
 Project development
- Prioritising species for conservation based on susceptibility/impact data and risk modelling – NSW Department of
Environment
- Myrtle rust identified as a priority for National Environmental Science Program
 PhD project funding looking at conservation of species identified from this project as being under threat
Myrtle rust research impacts

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 Thankyou
- Dr Angus Carnegie, Dr Suzy Perry
- Dr Fiona Giblin, Dr David Lee, John Huth, Peter Entwistle, Dr Kylie Ireland
- Dr Gordon Guymer, Bob Makinson
 The PBCRC for the support for this research
 For more information, please email [geoff.pegg@daf.qld.gov.au]