Important update on myrtle rust

24 November 2017

HELP CONTROL MYRTLE RUST

There are now 134 confirmed finds of myrtle rust: 4 sites in Northland, 82 sites in Taranaki, 37 in Bay of Plenty, 10 sites in Waikato and 1 in Auckland.

Unfortunately myrtle rust continues to spread, with a new discovery in Auckland this week. Progression of the disease is as expected with the increasing Spring temperatures leading to symptoms appearing in in previously asymptomatic trees or new infections from sporulating plants.

Ramarama (Lophomyrtus bullata) is still showing the highest prevalence of disease, amongst the plants surveyed.

The Project Crimson Trust is seriously concerned for the impact of myrtle rust on our Metrosideros species; there’s no way of predicting how our native plants will cope with this fungal disease. We are asking for your help as New Zealand faces a major biosecurity threat to native plants with the discovery of myrtle rust.

Myrtle rust

Identifying myrtle rust

Myrtle rust only affects plants in the myrtle family.  It generally attacks soft, new growth, including leaf surfaces, shoots, buds, flowers, and fruit. Symptoms to look out for on myrtle plants are:

  • 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) on older lesions.
  • Some leaves may become buckled or twisted and die off.

    Yellow bumps and brown patches typical of myrtle rust

The threat

The disease could be on any plants from an infected area taken to a revegetation site. It can also be carried on clothing or vehicles. Myrtle rust spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery.

If it becomes widespread it will impact all of New Zealand’s Myrtaceae to some degree and we are likely to lose some native species in their natural state. Ecological integrity will be compromised in places where myrtles are a dominant species. It is also likely to affect commercial activities (e.g. manuka honey industry), tourism, recreation and landscape values.

It is very important community planting groups, volunteers and all those who go into the forest follow certain hygiene protocols to restrict the spread of the wind-borne disease. Revegetation work is a potential vector for spreading myrtle rust. People doing voluntary conservation work of any type, could inadvertently spread the disease.  The latest information and advice is on MPI’s website here.

If you find anything suspicious

1. Do not move the plants from the site or your truck.

2. Take photos of the suspected myrtle rust and the whole plant.

3. Do not attempt to touch or collect samples as this may increase the spread of this disease.

4. If possible, isolate the plants with an igloo-hoop-like plastic cover.

5. Call MPI’s exotic pests and diseases hotline on 0800 80 99 66.

More information