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Protect plants from myrtle rust
Myrtle rust presents a serious biodiversity threat. It is a recent arrival in New Zealand, so it is hard to predict how damaging it will be.
What is myrtle rust?
Myrtle rust is a plant disease caused by the fungus Austropuccinia psidii. It produces powder-like spores that can be easily spread through direct contact or by the wind.
Once established on a host tree or shrub, it destroys new growth and soft tissues, eventually killing the plant.
At risk plants
Myrtle rust can infect hundreds of species in the plant family Myrtaceae, which in New Zealand includes such species as mānuka, pōhutukawa, rātā and kānuka.
Research shows the genus Lophomyrtus — which includes ramarama and rōhutu — is especially at risk. Based on countries where myrtle rust is more established, severe declines are possible for these plants, and others may prove susceptible in future.
Common exotic plants also at risk include: feijoa, bottlebrush, gum, guava, willow myrtle, lilly pilly (monkey apple) and brush cherry (Syzygium spp).
Reducing the risk of myrtle rust
Look out for myrtle rust when moving, buying, planting, or working with myrtles.
Note the following guidelines:
- Do not transport plants or green waste you suspect to be infected with myrtle rust (or any other pest).
- If you need to treat or remove infected plants or material, follow the advice on
- After working on Myrtaceae, sterilise tools and equipment with methylated spirits or 5-10 per cent bleach. Cover and contain clothes in plastic if moving them between the site and laundry. Wash exposed clothing in hot water.
- Limit pruning of Myrtaceae to autumn and early winter, as this stimulates new growth. Myrtle rust infects soft, young growing tissues of the plant, and is most virulent during warmer months.
- Consider removing susceptible exotic species such as lilly pilly and replacing them with resistant natives such as pittosporum. Susceptible plants form a "reservoir" population in which the fungus can build up.
- Report sightings through the reporter app (available via
Google Play) or contact
Visit myrtlerust.org.nz for identification guides, where it has been found and how to manage infected plants.
Advice on managing myrtle rust in a plant production context is also available from NZ Plant Producers.