Myrtle Rust Alert!

Austropuccinia psidii

28 June 2017

If you think you have seen this fungus call MPI’s exotic pests and diseases hotline on 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 was confirmed in New Zealand in 2017:

03 May Kerikeri plant nursery
17 May New Plymouth
21 May Te Kuiti
12 June Te Puke in the Bay of Plenty

The Ministry for Primary Industries (MPI) and Department of Conservation (DOC) have already put precautions in place to help stop any further spread. They are working with iwi, industry and local authorities to learn more about how this detection can be managed.

Myrtle rust is a serious fungal disease, readily spread by wind, that attacks plants of the Myrtaceae family. It can also 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.

Host plants

Many New Zealand natives are members of the Myrtaceae family, including Pohutukawa and Rata (Metrosideros), Kanuka (Kunzea), Manuka (Leoptospermum), Ramarama (Lophomyrtus), Rohutu (Neomyrtus), Swamp maire (Syzygium). There are 29 species in these genera.

Many exotic species grown in New Zealand are also members of the Myrtaceae family. Eighty percent of Australia’s native flora are members of the Myrtaceae family, notably species in the genera Agonis, Angophora, Callistemon, Chamelaucium, Corymbia, Eucalyptus, Eugenia, Kunzea, Lophomyrtus, Leoptospermum, Metrosideros, Myrciaria, Myrtus, Pimenta, Psidium, Syncarpia and Syzygium. All these feature in New Zealand landscapes.

The popular feijoa (Acca sellowiana) is also a member of the Myrtaceae family.

All members of the Myrtaceae family must be considered potential hosts of myrtle rust because the fungus has demonstrated in both Australia and Hawaii that it finds new myrtaceous host species which were not known hosts previously.

NZPPI is part of the response leadership team (response governance) and Malcolm Woolmore is a member of the Technical Advisory Group. We are actively working with MPI to raise awareness among plant producers to give us the best chance of early detection should the rust spread further.

How you can help

Myrtle rust spores are highly mobile. Like many rusts, they are easily spread across large distances by wind. They can also be transported by infected plant material, on clothing, equipment and vehicles, by insects and in rain splashes. Early detection gives us the best chance of containing an incursion.

Industry has an essential part to play in being on the lookout for symptoms and early reporting to MPI.

Plant producers, nurseries and garden centres are strongly urged to immediately inspect all their stock and nearby vegetation, especially varieties in the Myrtaceae family. Those in the Northland region should not ship or sell plants until they have undertaken an inspection.

If you find anything suspicious, call MPI’s exotic pests and diseases hotline on 0800 80 99 66.

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.
Look for:

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.

What to do if you find it

If you think you may have found myrtle rust on any of your plants:

Do not move any plants from your site
Take a photo - do not attempt to touch or collect samples as this may increase the spread of this disease
Immediately phone the MPI exotic pest and disease hotline on 0800 80 99 66

NZPPI’s here to help

NZPPI, on behalf of all members, is working closely with MPI and will do all we can to help manage this serious threat.

We’ll update our myrtle rust web page and let people know as things come to hand.

In the meantime, if you need help, please contact John Liddle at john@nzppi.co.nz or phone 021 370 168.

More information is available at:

NZ Government Myrtle Rust media release
MPI's website
NZPPI's Myrtle Rust webpage
New Zealand Myrtaceae - extract from Risk analysis of the Puccinia psidii / Guava Rust fungal complex (including Uredo rangelii / Myrtle Rust) on nursery stock - MPI 201l
Myrtaceae genera in Australia - extract from Australian Nursery Industry Myrtle Rust Management Plan (Version 3) – 2013
List of native and exotic myrtle family plants in New Zealand
Source: New Zealand Plant Conservation Network
Genera in the Myrtaceae family - Wikipedia