Myrtle rust is in Kaipātiki!
Here is what you need to know.
Myrtle rust is a disease that affects many of our native plant species.
Look out for bright yellow/orange powder on ramarama, rōhutu, swamp maire and other myrtle species - this is a key symptom of the disease.
If you see signs of myrtle rust, report your finding on iNaturalist.
What is myrtle rust?
Myrtle rust is a disease caused by a fungal pathogen (Austropuccinia psidii) which attacks plants in the myrtle (Myrtaceae) family. The pathogen arrived in Aotearoa/New Zealand in 2017. Since its arrival the disease has quickly spread across the North Island and has made its way to some areas of the South Island. Myrtle rust attacks a plant’s new growth, including leaves, stems, flowers and fruit, damaging the plant and in some cases leading to whole plant death.
How do I recognise myrtle rust?
The giveaway symptom of myrtle rust is distinctive yellow/orange powder on new growth. At early stages of infection this powder is found on the underside of the leaves, but will begin to cover all surfaces as the infection progresses. Myrtle rust is typically found in warm conditions, so keep your eyes peeled for symptoms during the warmer months.
Examples of different plants infected with myrtle rust can be found on the Myrtle Rust in New Zealand website.
Why should we care about myrtle rust?
Aotearoa/New Zealand is home to many myrtles, including native and non-native species, and there is real risk of localised extinctions of the more susceptible species. The disease also poses a significant risk to the ecosystems native myrtles are a part of. For instance, some native myrtles are pioneer species which alter conditions to create suitable habitat for other plants and animals, and many produce flowers which support pollinators. Without native myrtles our ecosystems would function very differently.
Myrtles are also culturally significant. Numerous species are present in a number of pūrākau (mythologies) and beliefs within te ao Māori (the Māori worldview); for instance, the belief that spirits travel to the afterlife through an ancient pōhutukawa at Te Rerenga Wairua/Cape Reinga. Pōhutukawa and rātā are also known as Aotearoa/New Zealand’s Christmas trees, a bright symbol of the summer holiday season.
What should I do if I find myrtle rust?
If you think you have found myrtle rust at your own property or within a reserve, the best thing you can do is report your observation using iNaturalist, which will help researchers monitor the disease.
Note: MPI’s pest and disease hotlines are no longer taking myrtle rust reports.
On your own property you are entitled, but not required, to remove infected plants or plant material. If you do wish to remove infected plants or plant material, follow hygiene measures to avoid further spreading the spores:
Cover the infected material before pruning
Landfill removed material in a sealed bag
Do not prune in windy conditions
Wash exposed clothing
Clean exposed equipment/tools
Do not place infected or potentially infected vegetation in green waste bins or community weed bins.
How can I help?
One of the most impactful actions you can take is to learn about myrtle rust and teach your whānau and wider community about it. There are a number of great resources listed below which can help you with this. Another key action you can take is downloading the iNaturalist app and reporting any suspected cases of myrtle rust you find. Encourage your friends and whānau to use it, too!
You might also consider carrying out a survey of your garden for myrtle species, from which you can make decisions about managing any you do have. Find a list of susceptible myrtle species in the ‘some helpful resources’ section below and avoid planting these.
If you choose to prune myrtles, we strongly advise doing this in winter months when regrowth is slower and new sites for myrtle rust on the plant are minimised. You might also decide to remove non-native myrtles and replace them with a different species: if you do this, remember to follow the hygiene measures listed above.
Educate yourself, your whānau, and your community about myrtle rust
Become a citizen scientist and report any sightings of myrtle rust
Survey your garden for myrtle species and make management decisions
Some helpful resources
Thank you to the Beyond Myrtle Rust team for their advice and guidance.