Gearing up to fight myrtle rust

ON THE LOOKOUT: The Ministry for Primary Industries held a hui this week at Muriwai Marae to share information about myrtle rust. From left are kaumatua Temple Isaacs, MPI director John Walsh, Rangiwahia trustee Mihi Harrington, DoC ranger Jamie Quirk, MPI response manager Lorin Lima and Ngati Porou botanist Waipaina Awarau. Picture by Liam Clayton

SURVEILLANCE teams are scouring all corners of the region for signs of myrtle rust and collecting seeds of precious native trees for storage.

Myrtle rust is a serious fungal disease that affects plants in the myrtle family, which include pohutukawa, rata, ramarama and manuka.

It was found in plants at a nursery in Northland in early May, and has since been found in Taranaki, Waikato, the Bay of Plenty, Auckland and Wellington.

It has devastated ecosystems in Hawaii and the east coast of Australia, and the Ministry for Primary Industries has identified it in the top three biosecurity threats to New Zealand.

The spores are thought to be capable of crossing the Tasman Sea from Australia to New Zealand on wind currents. Experts say that is probably how it arrived on New Zealand shores.

The whole Gisborne district falls into the high-risk category, with vast numbers of myrtle species and a hot and humid climate, particularly up the East Coast.

MPI is leading the Government response to the threat and has been conducting hui around the North Island, sharing information about the fungus and what communities can do to assist.

“The main thing people can do is to keep an eye out for it,” MPI director John Walsh said at a hui at Muriwai Marae this week.

“If you spot it, don’t touch it, as that can help it spread. Take a photo and phone MPI on 0800 80 99 66.

“If we are going to fight myrtle rust it is really important we know where it exists.”

Approaches to manage disease

MPI is working to identify approaches to managing this disease, but it says rust diseases are difficult to control.

It has not been found here yet, but it has been found as close as Te Puke.

“The likelihood of it getting here is hard to say, but since late spring we have seen a steadily increasing number of infections,” Mr Walsh said.

There are now about 190 infected sites around country. The biggest source is in Taranaki.

MPI has teams out monitoring in the bush all around the North Island, and the Department of Conservation is working with community, iwi and hapu groups on the Coast to collect seed of the different myrtle species.

There have been no detections in the bush yet, only in nurseries and private properties. But just because it is not seen does not mean it is not there.

“For most of its life it is invisible, until it sporulates, a fungus version of seeding, and gets bright golden yellow. It's very distinctive then,” Mr Walsh said.

Myrtle rust generally attacks soft, new growth, including leaf surfaces, shoots, buds, flowers and fruit.

The spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery.

Severe infestations can kill affected plants and have long-term impacts on the regeneration of young plants and seedlings.

It is not yet known how this disease will affect New Zealand species.

“It has slowly spread its way around the southern hemisphere, particularly since the 1930s, and it behaves differently everywhere it goes.

“It is hard to say exactly what it will do. On Raoul Island it is having quite a severe impact on some specimens of pohutukawa.”

Communities around the North Island were responding well to MPI’s awareness-raising campaign.

“The response we have been getting is fantastic,” Mr Walsh said.

“People know it has a serious effect, and could put our native species under threat, potentially lead to extinction, if it gets really bad.”

Ngati Porou botanist Waipaina Awarau is part of Te Poho o Huturangi o Taiao, a Ruatoria community organisation that surveys for myrtle rust and collects seed.

“These trees are our taonga species. The country’s largest pohutukawa is in Te Araroa. Imagine driving down the coast and seeing no pohutukawa.”

A Myrtle rust reporter app has been designed to help people take part in a nationwide move to monitor myrtle rust. It allows users to record a dozen potential host plants and easily report anything they find suspicious.

The app is freely available in the iPhone and Android app stores.


SURVEILLANCE teams are scouring all corners of the region for signs of myrtle rust and collecting seeds of precious native trees for storage.

Myrtle rust is a serious fungal disease that affects plants in the myrtle family, which include pohutukawa, rata, ramarama and manuka.

It was found in plants at a nursery in Northland in early May, and has since been found in Taranaki, Waikato, the Bay of Plenty, Auckland and Wellington.

It has devastated ecosystems in Hawaii and the east coast of Australia, and the Ministry for Primary Industries has identified it in the top three biosecurity threats to New Zealand.

The spores are thought to be capable of crossing the Tasman Sea from Australia to New Zealand on wind currents. Experts say that is probably how it arrived on New Zealand shores.

The whole Gisborne district falls into the high-risk category, with vast numbers of myrtle species and a hot and humid climate, particularly up the East Coast.

MPI is leading the Government response to the threat and has been conducting hui around the North Island, sharing information about the fungus and what communities can do to assist.

“The main thing people can do is to keep an eye out for it,” MPI director John Walsh said at a hui at Muriwai Marae this week.

“If you spot it, don’t touch it, as that can help it spread. Take a photo and phone MPI on 0800 80 99 66.

“If we are going to fight myrtle rust it is really important we know where it exists.”

Approaches to manage disease

MPI is working to identify approaches to managing this disease, but it says rust diseases are difficult to control.

It has not been found here yet, but it has been found as close as Te Puke.

“The likelihood of it getting here is hard to say, but since late spring we have seen a steadily increasing number of infections,” Mr Walsh said.

There are now about 190 infected sites around country. The biggest source is in Taranaki.

MPI has teams out monitoring in the bush all around the North Island, and the Department of Conservation is working with community, iwi and hapu groups on the Coast to collect seed of the different myrtle species.

There have been no detections in the bush yet, only in nurseries and private properties. But just because it is not seen does not mean it is not there.

“For most of its life it is invisible, until it sporulates, a fungus version of seeding, and gets bright golden yellow. It's very distinctive then,” Mr Walsh said.

Myrtle rust generally attacks soft, new growth, including leaf surfaces, shoots, buds, flowers and fruit.

The spores are microscopic and can easily spread across large distances by wind, or via insects, birds, people, or machinery.

Severe infestations can kill affected plants and have long-term impacts on the regeneration of young plants and seedlings.

It is not yet known how this disease will affect New Zealand species.

“It has slowly spread its way around the southern hemisphere, particularly since the 1930s, and it behaves differently everywhere it goes.

“It is hard to say exactly what it will do. On Raoul Island it is having quite a severe impact on some specimens of pohutukawa.”

Communities around the North Island were responding well to MPI’s awareness-raising campaign.

“The response we have been getting is fantastic,” Mr Walsh said.

“People know it has a serious effect, and could put our native species under threat, potentially lead to extinction, if it gets really bad.”

Ngati Porou botanist Waipaina Awarau is part of Te Poho o Huturangi o Taiao, a Ruatoria community organisation that surveys for myrtle rust and collects seed.

“These trees are our taonga species. The country’s largest pohutukawa is in Te Araroa. Imagine driving down the coast and seeing no pohutukawa.”

A Myrtle rust reporter app has been designed to help people take part in a nationwide move to monitor myrtle rust. It allows users to record a dozen potential host plants and easily report anything they find suspicious.

The app is freely available in the iPhone and Android app stores.


Symptoms on myrtle plants

  • The first signs of myrtle rust infection are tiny raised spots that are brown to grey, often with red-purple halos. Up to 14 days after infection, the spots produce masses of distinctive yellow spores.
  • 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.

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