Department of Conservation | Te Papa Atawhai
https://www.doc.govt.nz/
https://www.doc.govt.nz/
Introduction
Myrtle rust is a wind-borne fungal disease that can infect taonga species including pōhutukawa, mānuka, and rātā.Myrtle rust is an unwanted organism that has spread throughout the North Island, to parts of the South Island and Chatham Island.
Symptoms of myrtle rust are bright yellow-orange powdery pustules on young leaves, shoots, fruits and flowers of plants in the Myrtaceae family.
Myrtle rust cannot be eradicated from Aotearoa, but there are things you can do to help us track the spread and protect the ngahere/forest.
What it looks like
Myrtle rust attacks soft new growth including leaves, stems, buds, flowers and fruit.
Symptoms to look out for are:
- bright yellow-orange powdery eruptions on leaves (usually first appearing on the underside of the leaf) for new infections
- pale yellow brown-grey pustules (old spores) for older infections
- leaves and stems that are brown, buckled or twisted and dying off.
What to do if you see myrtle rust
Avoid contact with highly infected plants and do not collect samples as this might spread the disease.
If you identify myrtle rust on your property, find out what to do.
Make sure you wash your clothing, bag and shoes/boots when you get home.
To report a sighting of myrtle rust:
- take a photo of the rust and the plant it is on
- report to the iNaturalist website or iNaturalist app labelling your find as myrtle rust (Austropuccinia psidii).
Your reports of myrtle rust are vital in helping understand where myrtle rust is in New Zealand, how far it has spread and what species it is infecting.
If you find myrtle rust on public conservation land, contact your local DOC office.
Why myrtle rust is a threat
Myrtle rust affects New Zealand plants such as pōhutukawa, mānuka, rātā, swamp maire and ramarama. It affects exotic species including bottlebrush and lilly pilly. It also affects commercially grown species such as eucalyptus.
The conservation status of all native Myrtaceae was raised to ‘Threatened’ in 2018 after the arrival of myrtle rust.
Myrtle rust (Austropuccinia psidii) is also known as guava rust and eucalyptus rust.
Myrtle rust can:
- cause deformation and dieback of new leaves and shoots
- prevent flowers and fruit developing, preventing regeneration.
Seedlings and young plants are especially vulnerable and severe and repeated infection can result in plant death.
Myrtle rust poses a major threat to New Zealand’s native biodiversity as it affects entire plant families including climbers, trees and shrubs. These plants provide essential ecosystem services. For example, pōhutukawa is a coloniser of bare coastal rock and is an important species for coastal stability.
How it can spread
Myrtle rust spores are microscopic and can easily spread across large distances by wind. Myrtle rust was probably carried by wind to New Zealand from Australia. Spores can also be transported on contaminated clothing, insects, rain splashes and equipment.
Managing the threat
DOC has been working closely with the Ministry of Primary Industries to support research and initiatives that ensure Myrtaceae species remain for generations to come.
New Zealand has stringent biosecurity measures to protect against myrtle rust introduction. These include a complete ban on imports of cut flowers and foliage from myrtle species in New South Wales, Queensland and Victoria.
There are strict biosecurity procedures for DOC staff travelling between Raoul Island and the New Zealand mainland to prevent any people-assisted spread. Entry to the island is by permit only.
Beehive restrictions on public conservation land
DOC put immediate restrictions on beehive movements on specific areas of conservation land in a bid to reduce the spread of myrtle rust. The decision was made after research from Plant and Food Research Ltd indicated bees may be a vector for the spread of myrtle rust.