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Keep an eye out for myrtle rust this summer

As spring leads to summer, our native trees start to bloom. Pōhutukawa and rātā are bursting with red flowers – but another bloom will also be taking place. You may notice yellow pustules erupting on the young leaves and stems of our iconic Myrtaceae. This is the disease myrtle rust, caused by the airborne fungal pathogen Austropuccinia psidii.


Myrtle rust arrived in New Zealand via the wind in 2017. You can read more about its arrival and the research being done on this disease here. There’s one key way the public can get involved this summer: report myrtle rust on iNaturalist.

What to look for

Myrtle rust looks like pustules of rust-colored pollen. The disease is most commonly found on new growth (i.e., young leaves, stems, buds and flowers). When the leaf or plant material starts to die, the bright color of the pustules fade. When the infected areas have died, the plant looks singed around the edges.

Other plant diseases can look a little like myrtle rust, so the best indicators that what you’re seeing really is myrtle rust is 1) the yellow pustules and 2) the host plant - myrtle rust only infects plants from the Myrtaceae family. For more information on native and exotic myrtles found in New Zealand, check out the NZ Myrtaceae Key.

How to report myrtle rust

To report a suspected case of myrtle rust, you can download the iNaturalist app onto your phone or make an account on a laptop or desktop. Then, follow these steps:

  1. Take a photo of the plant – but don’t touch the diseased area!
  2. Create a new observation and upload photos of the infected plant.
  3. In the “what did you see?” section, type in “myrtle rust”.
  4. Depending on your phone’s privacy settings, you may need to add the location manually. Otherwise, the location field (which is very important!) should fill in automatically.

While that will be sufficient to make a record of the find, it is very helpful for researchers to know what the host plant is. Unfortunately, iNaturalist only allows one species to be recorded at a time. If you think you know what the host is or would like to make a guess, please add this to the “Notes” section. If you want to provide even more details, you can add your observation using the Myrtle Rust Reporter.

What happens next?

Researchers in the myrtle rust community will help confirm the record and the host plant. This will then be compiled on the iNaturalist platform to give researchers, land managers and the public a clearer idea of where the disease is spreading. If your record is in a new area or on a new host, you may even see action by local government to confirm the sighting


For more information about what you can do about myrtle rust, check out the Beyond Myrtle Rust FAQ.

If you’d like to learn more about myrtle rust research, you can follow Beyond Myrtle Rust on Facebook, Twitter @byondMyrtleRust and Instagram @beyond_myrtle_rust.