Myrtle leaf rust is a serious fungal disease that attacks members of the myrtle family.

It could affect our native pohutukawa, manuka and rata as well as feijoa and eucalypts, damaging or even killing highly susceptible plants.

Where do you find it?

“The disease was detected on Kermadec pohutukawa trees on Raoul Island in the Kermadecs at the end of March. It’s a good reminder to be aware of the threat and keep your eyes out for it,” says Dr Nick Waipara, Principal Advisor, Auckland Council Biosecurity.

“As well as Raoul Island, the rust is present in Australia and New Caledonia and has hit Australia particularly hard with more than 200 species affected.

“It could arrive here any day on the wind or on clothing or equipment. We want people to know what to look for, as a quick response is vital if it arrives,” he says.

“It could have a cultural, ecological and economic impact on New Zealand and could expand its host range here, as it has done in other countries.”

What to look for

Myrtle rust attacks young, soft, actively growing leaves, shoot tips and young stems, as well as flowers and fruit.

Initial symptoms are powdery, bright yellow or orange-yellow spots on the new growth, flower buds or even the fruit of some plants. The rust can appear red when the sexual types of spore are being produced.

What to do if you spot it

Report it immediately to the Ministry for Primary Industries (MPI) on 0800 80 99 66. Do not touch it or try and take samples as this increases the risk of spread. Note its location and take photos if possible.

What is being done?

“At the moment, responding quickly to any detection is key so we are raising awareness and carrying out passive surveillance of susceptible species on our land, including our active surveillance programme at the Auckland Botanic Gardens,” says Bec Stanley, Curator at the Auckland Botanic Gardens.

“The Auckland Botanic Gardens are also seed banking native threatened plants in this family to ensure at risk plants are collected and propagated as back-up plantings in case wild populations become infected in the future,” says Bec.

“Auckland Council is also participating in new research funded by the Biological Heritage National Science Challenge, which is a multidisciplinary project aimed at boosting the preparedness of New Zealand’s biosecurity system for an incursion of this plant pathogen. Scientists in the Biological Heritage National Science Challenge will work closely with Te Turi Whakamātaki (the Māori Biosecurity Network), the Department of Conservation and MPI to make every effort to prevent the spread of this disease to the mainland of Aotearoa New Zealand,” says Nick Waipara.

Visit the Ministry of Primary Industries (MPI) for more information.