Myrtle rust
Sphaerophragmiaceae - Austropuccinia psidii
BioSecurity

What does it look like?

Myrtle rust attacks young, soft, actively growing leaves, shoot tips and young stems. Initial symptoms are powdery, bright yellow or orange-yellow pustules on leaves, tips and stems. The developing lesions may cause a deformation of the leaves and shoots, and twig dieback if the infection is severe. Symptoms also sometimes affect flowers and fruit. Infection of highly susceptible plants may result in plant death.

Myrtle rust spores can be readily dispersed by wind or on clothing, equipment etc. Both modes of dispersal can transport spores very long distances.

Why is it a problem?

Myrtle rust (Austropuccinia psidii) is a serious fungal disease that affects plants in the myrtle family (family Myrtaceae). The myrtle family consists of trees and shrubs originating in both tropical and temperate regions. Well known members of the myrtle family include eucalypts, feijoa, guava, bottlebrushes (Callisternon spp.) and New Zealand native species such as pōhutukawa, rata, mānuka and kānuka.

Myrtle rust has been identified as a threat to New Zealand. The impact of myrtle rust has been particularly severe in Australia where it affects over 200 plant species. New Zealand has a number of species in the myrtle family considered to be at risk, among them iconic natives such as pōhutukawa, ramarama, rata and mānuka, but also feijoa, plantation and amenity eucalypts and numerous ornamental plants.

This fungus has continued to expand the recorded range of susceptible species as it has spread from country to country. It seems likely that myrtle rust will continue to find new susceptible species, or even new susceptible genera, now it has reached New Zealand.

More Information

Report sightings

This fungus has been detected on plants in a Northland nursery (May 2017) and in Kermadec pōhutukawa trees on Raoul Island (in late March 2017).

If you believe you have seen myrtle rust:

  • Do not touch the plant or the rust
  • Call MPI's Exotic Pest and Disease Hotline on 0800 80 99 66.
  • Note the location and if possible, take photos, including the type of plant the suspected rust is on.
  • Do not attempt to touch or collect samples as this may increase the spread of this disease.
  • If you accidently come in contact with the affected plant or the rust, make sure you bag your clothing and wash clothes, bags and shoes/boots when you get home.

Related Links

BioSecurity