Myrtle rust is a serious fungal disease, readily spread by wind, that attacks plants of the myrtaceae family. This plant family includes many New Zealand natives - including pohutukawa, rata, kanuka, manuka and ramarama!
Myrtle rust has not yet been detected on mainland New Zealand, but it can spread long distances on the wind and the Raoul Island incident is an important and timely reminder that it could readily reach here.
Myrtle rust established aggressively through Australia’s eastern seaboard (and further) after being first discovered in a foliage production nursery in New South Wales in 2010. Wind dispersal modeling has shown that, at times, wind dispersal patterns are suitable for it to be carried across the Tasman to New Zealand.
NZPPI is part of the response leadership team (response governance) and we are active in working with MPI to raise awareness among plant producers to give us the best chance of early detection should the rust reach mainland New Zealand. Early detection is essential if we are to have any chance of successful eradication.
What to look out for
Myrtle rust attacks young, soft, actively growing leaves, shoots and young stems, and sometimes flowers and fruit. 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 and plant death if the infection is severe and the species highly susceptible.
- bright yellow powdery eruptions appearing on the underside of the leaf (young infection)
- bright yellow powdery eruptions on both sides of the leaf (mature infection)
- brown/grey rust pustules (older spores) can appear on older lesions
- leaves may become buckled or twisted and die off
Rusts of this type are rare on many native species - any sighting should raise suspicion.
If you think you have seen this fungus:
Call MPI’s Exotic Pests and Diseases hotline - 0800 80 99 66
Take a photo - do not attempt to touch or collect samples as this may increase the spread of this disease.
Myrtle rust can be transported on clothing and equipment. If you think you’ve come into contact with myrtle rust spores in New Zealand or overseas, please wash your clothes and clean your equipment such as boots and tools thoroughly.
More detail at: