Potentially deadly disease to pohutukawa and manuka arrives in Northland

Pohutukawa could be at threat from myrtle rust.
MARION VAN DIJK/FAIRFAX NZ

Pohutukawa could be at threat from myrtle rust.

Some of New Zealand's most important native plant species are under threat after a potentially deadly myrtle rust disease has been found on pohutukawa plants in a Kerikeri nursery.

"It's a huge concern both environmentally and economically. There needs to be a swift response from the Government," Forest and Bird conservation advocate Kevin Hackwell said.

Conservation Minister Maggie Barry said there was no known method of controlling the disease in the wild, apart from application of fungicide in very small areas as a last resort. Even if it was eradicated, it could always arrive again from Australia.

Myrtle rust has been found at a tree nursery in Northland.
SUPPLIED

Myrtle rust has been found at a tree nursery in Northland.

The Ministry for Primary Industries has issued a biosecurity alert following the find. 

READ MORE: Deadly myrtle rust endangers manuka and pohutukawa

Labour Primary Ministries spokesman Damien O'Connor called for a "massive" injection of funding to protect some of the country's most iconic species. 

He also questioned whether there was a Government Industry Agreement to fight the disease. 

Myrtle rust can seriously damage various species of native and introduced plants in the myrtle family, including pohutukawa, rata, manuka, gum, bottlebrush and feijoa.

It is too soon to say whether it could have an impact on the multi-million dollar manuka honey industry. 

The fungal disease was discovered in a tree nursery in Kerikeri among five pohutukawa seedlings, Primary Industries Minister Nathan Guy said.

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"MPI has moved quickly and initiated a restricted place notice to restrict the movement of any plants and people at the site, and is treating nursery stock with fungicide spray as a precaution. Work is also underway to trace any stock that has left the nursery and all other nurseries in Kerikeri are being inspected today.

"The disease is prevalent in eastern Australia and Tasmania, and was discovered on Raoul Island in late March this year."

It is thought the disease arrived on the wind from Australia. While it is not known how long it has been on the mainland, it is possible it arrived as recently as when Cyclone Debbie hit in April.  

"Myrtle rust spores are microscopic and can easily spread across large distances by wind. Officials believe that wind was the likely pathway of incursion into Raoul Island, and it's likely that wind has carried spores to mainland New Zealand from Australia."

The rust rapidly spread from South America across to Queensland where it was first detected in 2010.

Funding to deal with the issue is initially to come out of the Department of Conservation operating budget.

Hackwell said he was disappointed that a contingency fund had not been set up that could be used by both MPI and the Department of Conservation.

"Just as they did with the response to the recent fruit fly incursion, the Government established a special fund to fight the problem." 

Project Crimson Project Crimson director Gordon Hosking has recently said New Zealand should have prepared for the arrival of the rust by growing New Zealand plants in Australia to see if they were susceptible. 

"It wouldn't take too long to find out but the issue is what do you do if they are susceptible. These rusts are notoriously difficult to eradicate. It's a matter of time before we get it. I'd hate to see some of our key species suffer, but if you raised some varieties that had some resistance, you are further down the track in preparing for its arrival." 

Conservation Minister Maggie Barry said that in Australia the fungus had different levels of impact on myrtle species, with some more seriously affected than others.

"Myrtle rust has long been expected to arrive in New Zealand, and since the Australian outbreak began in 2010, the Government has worked on a range of measures to help manage and adapt to the fungus in the long term if necessary," says Ms Barry.

"This includes accelerating work already underway to collect and store germplasm from affected species, searching for signs of resistant myrtle strains which could be incorporated into a breeding programme and monitoring at 800 locations across the country."

"DOC will also be conducting inspections of our myrtle species on public conservation land in Northland for any early signs of the fungus."

The public should call MPI on 0800 80 99 66 if they think they have seen the rust.

MPI said it was very important not to touch the plants or attempt to collect samples as it would spread the disease.

In particular, anyone who has purchased any plants from the myrtle family in the last month should check for physical signs and contact MPI if any are seen.

 - Stuff

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