Myrtle rust is a serious fungal disease that affects plants in the myrtle family. Plants in this family include the iconic pōhutukawa, mānuka and rātā as well as some common garden plants such as ramarama and lilly pilly.
On this page:
- Risk to New Zealand
- What you can do
- Symptoms to look out for
- Advice for specific groups
- What MPI is doing
- Find out more
UPDATE – 1 May 2018
New approach being taken to manage myrtle rust
If you think you've seen myrtle rust, don't touch it, take a photo, and call 0800 80 99 66.
Myrtle rust (Austropuccinia psidii) has been found in 11 North Island regions – Auckland, Thames-Coromandel, Waikato, Bay of Plenty, Taranaki, Taupo, Gisborne, Manawatu, Wellington and Tasman.
It is also widespread on Raoul Island in the Kermadec group north-east of Northland.
The fungus attacks plants belonging to the Myrtaceae family, also known as the myrtle family.
It is found in many parts of the world including New Caledonia and all along Australia's eastern seaboard.
Spores can spread easily
Myrtle rust spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery.
Evidence suggests the fungus arrived in New Zealand carried by strong winds from Australia where it is well established all down the eastern coast.
The Ministry for Primary Industries (MPI) and the Department of Conservation (DOC), with the help of local iwi, the nursery industry, and local authorities ran a year-long operation to attempt to contain and control myrtle rust and determine the extent of its spread.
Myrtle rust could affect iconic New Zealand plants including pōhutukawa, mānuka, rātā, kānuka, swamp maire and ramarama, as well as commercially-grown species such as eucalyptus.
Severe infestations can kill affected plants and have long-term impacts on the regeneration of young plants and seedlings.
List of plants in the myrtle family [PDF, 477 KB]
What you can do
Report suspected myrtle rust
It is important to understand where the rust has spread to and where it is active. Look out for signs of myrtle rust. If you think you see the symptoms of myrtle rust:
- don't touch it
- call the MPI Exotic Pest and Disease Hotline immediately on 0800 80 99 66
- if you have a camera or phone camera, take clear photos, including the whole plant, the whole affected leaf, and a close-up of the spores or affected area of the plant.
Remember, don't touch it or try to collect samples as this may increase the spread of the disease.
Do not attempt to self-treat trees and plants with a fungicide, either for a cure or to try to prevent myrtle rust infection. We are still building a picture of whereabouts the disease is present nationally, and if people use preventative sprays, it could suppress symptoms, and prevent us from making the best management decisions for the country.
Arrive clean, leave clean
The forest you visit could be infected with myrtle rust without you knowing it. Before entering such areas for work or recreation, you should minimise the risk of spreading the rust by ensuring your equipment, clothing, and tools arrive clean and leave the area clean.
Buy healthy plants and prune in cool weather
Make sure myrtle plants bought for your garden are free from the symptoms of myrtle rust. Inspect the leaves and stems of plants before you buy them, and avoid buying plants that have signs of disease. Keeping your plants in the best condition and health possible is likely to improve their resilience and ability to cope with pests and diseases including myrtle rust.
We recommend avoiding heavy pruning during warm weather as this will encourage susceptible new growth. Instead, prune myrtles only in late autumn and early winter to avoid encouraging new growth during warm weather when myrtle rust spores are more likely to form. When pruning, use good hygiene practice, sterilise, and disinfect tools and equipment with pure alcohol or methylated spirits.
Monitor your plants
We recommend regular monitoring of myrtle plants for any sign of myrtle rust, particularly new, young growth, shoots, and seedlings. Early detection in your garden will give you time to consider options for myrtle rust control on your property. If myrtle rust does establish on your property, note which plants become the most severely affected.
It generally attacks soft, new growth, including:
- leaf surfaces
- shoots and buds
- flowers, and fruit.
Symptoms to look out for on myrtle plants are:
- bright yellow powdery eruptions appearing on the underside of the leaf (young infection)
- bright yellow powdery eruptions on both sides of the leaf (mature infection)
- brown/grey rust pustules (older spores) on older lesions.
- grey, 'fuzzy' spore growth on undersides of leaves.
Some leaves may become buckled or twisted and die off.
A guide to identifying myrtle rust [PDF, 5.4 MB]
Pictures of some types of trees that may be affected
We send out a monthly email newsletter on all myrtle rust activities, including research updates. It is sent on the last Wednesday of the month.
All myrtle species in New Zealand are at some risk from myrtle rust infection, but there are actions you can take to give your myrtle plants the best chance over the long term.
Read our specific advice for:
Myrtle rust has now spread to many parts of New Zealand that have a suitable climate. We also have limited tools available to manage the disease. From 1 May 2018, we have adopted a new approach which involves:
- scaling back our operations and stopping surveillance in areas that are known to be infected
- conducting surveillance only in new areas where myrtle rust has not yet become established
- treating new infections only at sites with isolated low-level infections where we can quickly suppress symptoms and attempt local elimination in the short term
- lifting movement restrictions in known infected areas
- allowing landowners with myrtle rust infection on their property to decide how to manage their plants
- issuing permissions to landowners in known infected areas allowing them to dispose of infected myrtle plant material in local landfills as general waste
- working with DOC, iwi, the nursery industry, scientists, and local authorities to explore options for future management.
Why are we changing our approach?
It is clear that eradication of myrtle rust from New Zealand is not feasible using the tools we have available. Restricting human activity at this time will not make a significant contribution to slowing the spread of the disease. Focusing our efforts on surveillance in areas where myrtle rust has not been found and undertaking spray and tree removal only at sites with isolated low-level infections will allow us to quickly suppress symptoms and attempt local elimination in these areas in the short term.
At the same time, we are investing significantly in scientific research to develop new tools, build an understanding of myrtle rust and explore possible treatment and management options. Regardless of where you live, myrtle rust continues to be considered an unwanted organism throughout New Zealand. We continue to encourage landowners to regularly check the health of their myrtle plants.
Our approach in areas where myrtle rust hasn't been found
We encourage residents in these areas who see signs of myrtle rust to call our Biosecurity Hotline (0800 80 99 66).
Our surveillance effort will target areas where myrtle rust has not become established.
Restrictions may still be used where infection levels are extremely low.
Our approach in known infected areas
We’ll be contacting affected owners and giving them self-management packs. The packs will:
- set out their responsibilities under the Biosecurity Act
- give advice about maintaining their property to minimise the spread of disease.
Other long-term planning activities
We are engaging with iwi and councils in affected regions to look at ways that MPI can support communities who wish to conduct their own biosecurity activities. We are also developing a programme to provide training to support community-based surveillance for interested groups in their regions. A long-term strategy will be developed over the next 2 years, with input sought from groups including iwi, councils, industry and DOC.
Research is vital to help us understand myrtle rust and limit its impact on our myrtle plants. MPI has commissioned a comprehensive research programme made up of more than 20 projects and valued at over $4.5 million.
- Media releases for myrtle rust from 2017 and 2018
- Myrtle rust A4 Poster [PDF, 724 KB]
- Read more about myrtle rust
- Download the myrtle rust fact sheet [PDF, 1.5 MB]
- Myrtle rust – DOC website
Watch videos on YouTube featuring 'Bug Man' Ruud Kleinpaste
Who to contact
If you have questions about myrtle rust, email firstname.lastname@example.org
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