28 Nov 2017

Fears myrtle rust could spread

10:47 am on 28 November 2017

A plant disease which could kill off native plants, like pōhutukawa, is expected to spread over the summer months.

Myrtle Rust has been found in a plant nursery in Taranaki.

Myrtle rust Photo: Supplied

The plant disease attacks myrtle species, including pōhutukawa, ramarama and mānuka. The disease was first discovered in Northland in May, and several cases have since been confirmed in Taranaki, Waikato and Bay of Plenty.

More than 2000 potential sightings of myrtle rust have been reported to the Ministry of Primary Industries since May this year.

Of those, two cases have been confirmed in Auckland.

The first case was confirmed at a commercial property in Kumeu. On Monday, MPI confirmed a second discovery on a private property in St Lukes.

MPI response controller Dr Catherine Duthie said the disease poses a real risk to the plants.

"I think that it's entirely possible that there is a real threat, particularly to pōhutukawa and ramarama," she said.

"In Australia there have been plants that are critically endangered because of myrtle rust, so if we see the same sort of thing in New Zealand then we have great cause for concern."

About 90 per cent of the 136 locations known to be infected involve ramarama or pōhutukawa.

Dr Duthie said the disease thrives in a humid and warm environment, so while it was unlikely to affect plants across the whole country, MPI expected more cases to be confirmed over summer.

What to do if you spot what looks like myrtle rust: (source: MPI)

  • Don't touch it or try to collect samples as this may increase the spread of the disease.
  • Call the MPI Exotic Pest and Disease Hotline immediately on 0800 80 99 66
  • If you have a camera or phone camera, take clear photos, including the whole plant, the whole affected leaf, and a close-up of the spores or affected area of the plant.
  • Do not attempt to self-treat trees and plants with fungicide; MPI says this could prevent it "making the best management decisions for the country".

Read more here

Get the RNZ app

for ad-free news and current affairs