The battle to beat the yellow myrtle rust that won't sleep

Friday, 26 May 2017

MPI myrtle rust regional co-ordinator Mark Bateman is leading the battle against the spread of the fungus from New Plymouth's Civil Defence headquarters.

The man heading the fight against the spread of myrtle rust comes from a military background.

Given the potential serious threat to the country's plant heritage and economy Mark Bateman needs every ounce of his previous pest prevention and combat experience he can draw on.

On the search for Myrtle Rust in Taranaki. (Video first published May 2017)

Bateman is the Ministry for Primary Industries regional controller based in Taranaki helping hold back the seemingly inevitable spread of the yellow coloured fungus across the country.

'We're getting finds on a regular basis, it's a moving feast and the battle gets harder everyday,' he says.

**READ MORE:

Connor Whiteley of Ecology New Zealand and Kelsi Bolstad of the Taranaki Regional Council are on the frontline in the battle against myrtle rust.

* Deadly myrtle rust bells rang out for nursery owner as soon as he saw it**

* Myrtle rust now discovered at Te Kuiti tree nursery in Waikato

Brent Rogan of the Ministry for Primary Industries NZ checks leaves for myrtle rust.

* Myrtle rust spread has 'potential to change landscape'

* Highly contagious myrtle rust plant disease found in Taranaki

Myrtle rust fungal spores found on plants such as pohutukawa, rata and manuka.

Bateman is confident myrtle rust can be defeated.

'Confidence is waning at every new positive find but we are confident we can stop it,' he says.

MPI staff search for signs of myrtle rust in a Taranaki garden

'We're not at a stage yet where we have given up.'

'It has potential but at this stage we are taking the view we don't have to live with it.'

MPI myrtle rust control centre at New Plymouth's Civil Defence headquarters.

Bateman says the team of scientists and botanists are unsure how the spores arrived but assume at this stage they were wind-borne.

'The weather is the biggest threat to containing and if the strong winds continue the damage will spread.'

New Zealand has had its fair share of biosecurity breaches from pest incursions - didymo, dutch elm, kauri die back, and fruit fly which Bateman was personally involved in.

A 2011 Ministry of Agriculture and Fisheries report concluded the likelihood of myrtle rust entering NZ was moderate to high if there was no specific risk management in place.

Now myrtle rust has hitchhiked across the Tasman Sea and invaded our shores to add to a myriad of plant diseases already here.

So far the Ministry for Primary Industries focus has been in the two affected regions with surveillance teams.

Department of Conservation and industry related staff and iwi also checking high-risk surveillance sites in other areas around the country.

There are approximately 800 high-risk sites being checked near ports, places of arrival, and areas likely to be wind-borne incursions.

Myrtle rust may sound like someone's dear maiden aunt but it has potentially more teeth.

It could wipe out native forests and leave us with just postcards of pohutukawa at Christmas to marvel over.

How this latest danger affects our native plants and economy in Taranaki is anyone's guess, plant experts say.

Our closest neighbours Australia, where myrtle rust affects more than 200 plant species, could hold the key on how much damage the rust will affect our native plant life.

But environmental conditions, temperature, rainfall, humidity and wind vary widely from each country.

From what is known myrtle rust damages plants in the myrtaceae family, among them pohutukawa, rata, ramarama, manuka, and eucalypts.

The critically endangered Bartlett's rata, of which only 14 trees are found in Northland, could be the first notable mortality if the disease got hold in the region.

Teams of white overall clad biosecurity staff from the Ministry for Primary Industries, and Department of Conservation have been on the ground in Taranaki since myrtle rust was discovered almost a fortnight ago at a nursery north of New Plymouth.

The work is painstaking, carefully examining leaves from suspected myrtle plants and looking for the tell tale yellow spores, or black brown rust spots, before taking samples which are couriered the same day to a lab in Auckland for analysis.

Strict decontamination procedures apply for anyone going on and coming off each site.

Overalls and gloves are bagged and incinerated, and uncovered surfaces, such as boots and cellphones, sprayed and wiped clean with alcohol at every site inspection.

Samples are double bagged before being sent away to be analysed.

Infected plants are removed and buried, while a 'firebreak' is placed around the property, and neighbouring properties inspected.

So far 20 properties from 450 reported 'sightings' in Taranaki, Waikato and Northland have returned positive readings for myrtle rust.

The positive results include spores on native pohutukawa, lophomyrtus, eucalypt gum trees, and manuka.

The manuka discovery is important as a potential threat to the lucrative manuka honey industry.

Property owners are understandably reticent about being identified and are holding out their businesses will not be taped off as 'restricted places' and forced to close down for an unknown period under the Biosecurity Act.

Many of spore discoveries have been found in nurseries and plant centres where the disease can thrive in warm, humid and wet conditions.

The distinctive spores have also been found in private gardens and orchards.

The public's vigilance, referred to as a 'biosecurity army of 4.7million' is helping MPI and the Department of Conservation build a picture of where the rust disease is located so the ministry can manage the fungus in the long term, MPI response director Geoff Gwyn says.

Myrtle rust was first discovered in Australia in 2010 and is now widespread along the east coast between New South Wales and Queensland infecting and killing new leaf growth, stems, fruit and flowers from plants in the myrtaceae family.

Outbreaks have also been found in Tasmania and Darwin proving temperature extremes are not a barrier to stopping the fungal spread.

The damage to forests can be dramatic, as witnessed across the Tasman.

Eradication proved unsuccessful in Australia and methods such as spraying fungicides is now used to contain more outbreaks.

Aerial surveys have shown large tracts of pohutukawa having already been destroyed on Raoul Island, after it is believed wind borne spores travelled from Queensland.

Research botanist Angus Carnegie found that after four years of the disease being discovered in Australia there was widespread damage with mature trees dying in native rainforests along the Queensland and New South Wales coastline.

As a result the disease is treated as a serious biosecurity threat to Australia causing significant impact on eucalypt forests, nurseries, and oils and cut flower businesses.

The disease is thought to have originated from South America where it has caused severe damage to commercial eucalypt and guava plantations, and orchards in the 1970's.

A strain discovered in Jamaica helped bring about the collapse of the country's allspice industry in the 1930's, while in Hawaii there was widespread damage to the endangered lilly pilly, or eugenia.

Since the fungus was found in Australia in 2010 significant readiness work has been undertaken for myrtle rust incursion, MPI response incident controller David Yard says.

'It had always been considered that New Zealand was at risk, given the propensity for the pathogen to travel long distances on the wind,' Yard says.

In the past six years MPI have made significant developments including tougher importing requirements to stop any imports of plant material from myrtle species into New Zealand from Australia, faster identification of myrtle rust fungus and species it infects, and closer collaboration between MPI, DoC, iwi, councils, industry and science community.

'Apart from potentially losing some of our most valuable native trees, it is unknown how the myrtle rust will affect various industries, such as manuka honey, and eucalypt forests here,' he says.

Plant ecologist Connor Whiteley is one of those at the coalface detecting new spore locations.

Whiteley is in no doubt the seriousness of the infestation as he shows a photo from his cellphone of a native lizard.

'It's not only the plants and trees but also these guys,' he says.

'This is why it is serious.'

Marlborough-based hardwood plantation researcher Paul Millen shares the concerns of his colleagues.

'We really don't know what the effects will be as the impact it has had in Australia has been variable, and the species is so genetically diverse,' he says.

'It's interesting it has been popping up so far in nurseries and plant centres which have the ideal conditions for its growth.'

Millen is surprised plants endemic to NZ were not tested in Australia to find susceptibility to the disease and levels of infection.

'It's been around for a long time, I'm surprised nothing has been done, but it's here now and we have to find a way to live with it.

'We've had bigger challenges to deal with, such as kauri die back.'

Nursery and Garden Industry of Australia national biosecurity manager John McDonald says the disease continues to have a 'varying pathogenic impact' on native forests in Australia.

'Some species are very susceptible but many other species have degrees of resistance where we see very little damage,' he says.

Overall the infection across the native forests and bush has been more localised, with highly susceptible species found in pockets, than widespread coverage.

'Surprisingly there has been very little impact on the eucalyptus species,'

The Australian timber industry has not suffered any significant economic loss from myrtle rust, he says.

'We have had some economic losses in nursery production due to some commercial plant species being highly susceptible to myrtle rust, particularly in the early days of the incursion.

'These species have fallen out of favour and replaced with less susceptible species and industry continues to successfully produce a vast array of plants in the myrtaceae family.

The real cost to the nursery industry has been in maintaining plants free of myrtle rust through fungicide management and costs associated with interstate trade, he says.

'The industry has removed highly susceptible plant species from production and replaced them with resistant cultivars and species.

'There's also a very successful myrtle rust management plan developed to ensure our sector does not provide a reservoir of disease inoculum within the environment.'

Many growers have successfully cropped across the myrtaceae family in areas where myrtle rust was detected, he says.

McDonald says one of the keys tasks for New Zealand will be to remove highly infected hosts from the environment, and watch for naturally resistant cultivars within urban, or natural environments.

'The NZ industry and government should monitor the susceptibility of plant species, record and rank the level of susceptibility and replace those that have an extreme ranking with alternative species.'

The NGIA is in close contact with its NZ counterpart, the New Zealand Plant Producers Industry, and had provided the NGIA Australian Myrtle Rust Management Plan to help combat the disease, he says.

Taranaki organic horticulturalist Phillip Tarr is critical of what he calls a lack of public information on how to combat the disease.

Tarr says he recently planted tea tree on his Tikorangi property to attract bees, and is concerned on what affect myrtle rust will have on the young plants.

'I don't think we are being told the whole truth about how it arrived,' he says.

'It seems unusual there have been only pockets of infestations found, when the whole of Taranaki's west coast is exposed.

'Why is it not more widespread?'