Technology offers hope in the fight against myrtle rust

New research using remote sensing technology has delivered promising results to scientists looking for innovative ways to help nurseries combat the spread of myrtle rust.

Scientists at Crown Research Institute Scion have found a way to quickly detect myrtle rust days before plants show signs of infection, providing hope that nurseries in the future can start control treatment much sooner and stop disease outbreaks in their tracks.

Working in a containment laboratory, the Scion team, led by data scientist Elizaveta Graevskaya, used high-precision equipment to detect myrtle rust infection in leaves of rose apple deliberately inoculated with the myrtle rust pathogen.

Using thermal imaging the team detected decreases in leaf temperature in infected plants at least a day before symptoms could be seen. Transpiration measurements showed the temperature drop was caused by higher rates of water evaporation from the leaves as the fungal infection punctures individual cells, which cooled the leaves down.

Scientists provide an update on their myrtle rust research

Three years into the Beyond Myrtle Rust research programme, Manaaki Whenua reports its researchers are moving into a key phase. Studies to understand the ecosystem impact of the disease have produced a substantial body of data, and researchers are now heading to the genetic laboratory, and to analysis and reporting

Senior Researcher Dr James McCarthy says the role that some Myrtaceae species, such as ramarama, play within a forest ecosystem is largely unknown.

“Unless you know how Myrtaceae species contribute to the functioning of New Zealand forests, you don’t know what the impact will be if we start to lose them.”

James says very little was known about some of New Zealand’s 28 native Myrtaceae species, 27 of which are endemic, before myrtle rust appeared in the country.

Australian plan to tackle threat from devastating myrtle rust fungus

A national survey has been conducted to help save Australian native species from the devastating myrtle rust disease.

A national living collections database of myrtle rust-susceptible plant species will be created from the survey, open to those across the and Botanic Gardens Australian and New Zealand (BGANZ) network and beyond with species from the family myrtaceae in their collections.

Myrtle rust spores are microscopic and the disease is spread mostly via wind, but the thousands of spores can also be spread via wildlife, infected plant material, contaminated equipment, clothing and vehicles.

The disease can cause deformed leaves, heavy defoliation of branches, reduced fertility, dieback, stunted growth and plant death.

The wind is believed to have carried spores to this country from Australia, where myrtle rust was first found in 2010.

Myrtle rust is found on Chilean guava on the Chatham Islands

Myrtle rust has been found on the Chatham Islands.

The  disease, caused by the invasive fungus Austropuccinia psidii, impacts plants in the Myrtaceae family (myrtles) including iconic New Zealand species like pōhutukawa. But  there are no endemic Myrtaceae on the islands and the find was made on the highly invasive Myrtaceous weed Chilean guava (Ugni molinae).

This has led Peter de Lange, a researcher with the Beyond Myrtle Rust programme, to believe there could be a silver lining to this discovery.

In late March, a member of the public brought a diseased plant sample to the Department of Conservation (DOC). The sample, which was confirmed as myrtle rust, was from the north end of the main island.

“Since myrtle rust is spread by wind and the Chatham Islands are downwind of New Zealand, its arrival was inevitable,” says de Lange, who had been surveying the Chatham Islands for myrtle rust before COVID lockdowns restricted travel out of Auckland.

Trans-Tasman collaboration unlocks genetic secrets behind myrtle rust

In a trans-Tasman collaboration, scientists have sequenced the genome of Austropuccinia psidii, the fungus responsible for the disease myrtle rust, and have produced the world’s largest assembled fungal genome.

Their work was recently published in the journal G3: Genes, Genomes, Genetics

This  marks a first step towards revealing key genetic features of the disease threatening myrtle plants in both Australia and New Zealand.

“If you’re going to go after a pathogen, it is important to get some understanding of its genome,” says Grant Smith, a Principal Scientist at Plant & Food Research in New Zealand.

Myrtle rust is found on pohutakawa plant on the West Coast

Myrtle rust has been detected for the first time on the West Coast on a young pōhutukawa plant, Biosecurity New Zealand (a branch of the Ministry for Primary Industries) confirmed today.

Biosecurity New Zealand was notified of the potential find on a commercial property in Greymouth and investigations confirmed it is myrtle rust.

Biosecurity New Zealand is advising local gardeners, orchardists and nurseries to monitor their trees and take protective action if they see signs of the disease.

Kauri dieback and myrtle rust research to be accelerated

Research, Science and Innovation Minister Megan Woods has announced a funding increase of $13.75 million over three years from the Strategic Science Investment Fund (SSIF) for research to combat the spread of kauri dieback and myrtle rust.

The Biological Heritage National Science Challenge is developing the platform plan for the SSIF.

Kauri dieback is threatening the country’s kauri with extinction and myrtle rust is threatening many iconic native species.

The new investment will be used to focus and accelerate the work already being done by Government agencies, councils, research providers, Māori and interest groups. A high-level strategy is being developed by the BioHeritage Challenge.

The strategy will align with BioHeritage’s three big goals – empower, protect, restore – and the research priorities already identified by the kauri dieback and myrtle rust Strategic Science Advisory Groups (SSAGs).

BioHeritage leader Dr Nick Waipara, of Plant & Food Research, says a core group of people with diverse expertise is being brought together to develop the strategy and subsequent workplan.

“While details are still being confirmed, it’s our intention to work closely with all key players as the strategy is developed. There has already been a lot of careful thinking about research needs in these areas and it’s our intention to build on this – not start from scratch.”

Dr Waipara  says kauri dieback and myrtle rust are critical threats to New Zealand’s environment and the team is acutely aware of how urgently something needs to be done to stop the diseases spreading.

“Connecting experts from diverse institutions is what National Science Challenges are all about – we independently focus collective thinking on nationally significant problems such as kauri dieback and myrtle rust,” he said.

“An integral part of this is to work closely in partnership with Māori.

“While we’re realistic about what can be achieved in three years, we feel confident that our collective approach will help make a big difference for Aotearoa.”

Source: Biological Heritage National Science Challenge

CRIs are collecting seeds in the race against myrtle rust

Pōhutukawa, mānuka, kānuka and other New Zealand seeds are being collected, grown, and tested for resilience to myrtle rust, a disease with the potential to wipe out entire native species and drastically change the country’s native landscape.

Myrtle rust attacks and can seriously affect plants in the Myrtaceae (myrtle) family, including pōhutukawa, mānuka, kānuka and rātā.

The fungal pathogen that causes myrtle rust is called Austropuccinia psidii. This fungus produces millions of small yellow-coloured spores that are easily wind-blown to new plants.

The pathogen was first found in Australia in 2010 and seven years later was identified in New Zealand. Since then it has spread quickly and has been reported on at least 600 properties.

An article by Suzette Howe, posted on the Manaaki Whenua – Landcare Research website, says the Ministry for Primary Industries (MPI) has launched a full-scale attack to better understand the disease and limit its impact on NZ’s  Myrtaceae plants.

Manaaki Whenua – Landcare Research is one of a team of institutes taking part in the research programme.  It will be working on the project closely with Plant & Food Research over the next two years.

“What we are trying to do is work out which species are going to be affected by myrtle rust, so to do that we are collecting seed from a whole range of Myrtaceae species, i.e. from the family that is going to be affected by myrtle rust,” says ,” says Manaaki Whenua – Landcare Research scientist Dr Gary Houliston.

“They’ll be sent to Australia to a screening facility, where they will be challenged with myrtle rust to see what’s susceptible,” he says.

Plant & Food Research plant pathologist Grant Smith, another of the key researchers working on the project, has worked in Australia helping with their response to myrtle rust and now oversees the seed collecting in New Zealand.

“Right now, what we are trying to do is get enough science data so we can make some decisions in 18 months about how we can respond from a science perspective to myrtle rust in New Zealand – for example, do we have resistance in mānuka that we can exploit in a breeding programme?” he says.

“We are also selecting material to safeguard via germplasm collections or seed banking,” says Dr Smith.

Testing seed resilience to the disease will give researchers information around ‘seed lines’ in New Zealand provinces that show a lot of resilience.

Mānuka and kānuka seeds are the first species to be collected and sent to Australia to be tested. From there, over the next year researchers will collect pōhutakawa and rātā and coordinate with other groups like Scion who are also doing research into this.

“This phase is what I consider to be a ‘secure future options’ to ensure we have options available for decisions we have yet to make,” says Dr Smith.

“In Australia, species extinction across the natural range of the plants is now becoming apparent. Understanding what resistance we have in our native plants, and seed banking those plants now before things get too bad, is essential to ensure we have the plant species available for future options,” he said.

All seed sent to Australia will be destroyed at the end of the project. Extra seed collected during the project is stored in seed banks in New Zealand.

Source: Manaaki Whenua – Landcare Research

Officials to take new approach to managing myrtle rust after it is found in South Island

The Ministry for Primary Industries and the Department of Conservation say the fight against the plant disease myrtle rust is changing gear, given the prevalence of the disease across susceptible parts of New Zealand.

Myrtle rust has now been confirmed in the Tasman region at the top of the South Island, which means the disease has been found across almost all regions identified as most vulnerable based on habitat suitability and wind patterns.

“When myrtle rust was first discovered on mainland New Zealand in May last year, we said it would be a challenging disease to contain and eradicate but we would give it a good crack,” says the ministry’s myrtle rust response spokesperson, Dr Catherine Duthie.

“There has been an enormous operational effort over the past 11 months, but the windborne nature of the disease means that containment has not proved possible. We have signalled for a while the likely need to change gear from intensive surveillance and the removal and destruction of host plants to one where we look to manage the disease over the long term.”

The fungus has been found in Tasman region on ramarama (Lophomyrtus) on a residential property in Collingwood in Golden Bay and a commercial property at Pohara.

Moreover, the ministry has confirmed infections on five properties at Omori on the south-western edge of Lake Taupō, which is also a new region for infection.

“We now have well over 540 infected sites across the North Island and now the top of the South,” says Dr Duthie. “Because of the windborne, pernicious nature of the disease, we have to anticipate that there are likely to be many more infected sites beyond these.”

Dr Duthie says the focus of efforts now had to be placed on a science programme designed to lift our understanding around the disease such as ways to treat myrtle rust, resistance and susceptibility, and to improve seed banking collection.

“A second key focus has to be on working with communities across New Zealand to support regional efforts to combat myrtle rust.

“As we transition to long-term management, MPI and the Department of Conservation (DOC) will be engaging with iwi and hapū, territorial authorities, the plant and nursery industries, and communities to support the development of regional programmes.

“This could include regional surveillance programmes, identification and protection strategies for taonga plants and special locations, advice to landowners, seed banking, and broad community engagement.”

As part of involving and informing communities at the grassroots, the ministry and DOC will hold meetings with iwi and councils in affected regions over the coming months.

“We think this regional and community effort is really important.

“One of the most critical things is for people to continue to report suspected infections. We need to keep tracking the spread of the disease so we can better understand how it might behave in New Zealand and what its long-term impacts might be.

“This will help us to understand resistance of native species and will be vital to our myrtle rust science programme.”

More than 540 properties are known to have been infected by the fungal disease since it was first detected on mainland New Zealand in mid-May 2017. Since then, more than 5,000 myrtle plants have been securely removed and destroyed, and more than 95,000 myrtle plants inspected.

Members of the public are encouraged to continue to report any possible cases to the biosecurity hotline – 0800 80 99 66.

DOC will continue to focus on seed collection to secure the long-term future of native myrtle plants and monitoring biodiversity impacts to inform science and management actions. It will also continue efforts to protect sites of high ecological and cultural significance.

Distribution of detections

At 6 April 2018, myrtle rust has been detected on 547 properties across nine regions: Northland (4 properties), Auckland (82), Waikato (61), Bay of Plenty (123), Taupō (5), Taranaki (233), Manawatu (3), Wellington (34), Tasman (2).

Response facts and figures

Since myrtle rust was first detected on mainland New Zealand, officials have:

• inspected more than 95,276 myrtle plants across the high-risk areas of the North Island and upper South Island
• co-ordinated field activities of 7 surveillance teams and 4 plant removal teams
• dedicated more than 104,000 hours to respond to the myrtle rust threat
• found myrtle rust on an average of 45 properties each month (ranging from 2 in October 2017, to 184 in March 2018)
• removed and securely destroyed more than 5,000 infected myrtle plants
• undertaken approximately 330 laboratory tests of myrtle plant samples
• received more than 3,300 calls from members of the public regarding suspected myrtle rust infections
• with the Māori Biosecurity Network, held hui around the North Island to share knowledge of myrtle rust and provided surveillance training to more than 100 people on marae so they could monitor taonga myrtle plants
• worked in partnership with iwi kaitiaki, councils, and community volunteers to establish a community-driven surveillance programme on Mauao (Mt Maunganui) historic reserve.

Source” Ministry for Primary Industries

Myrtle rust found for first time in Manawatu

Myrtle rust has been detected in Manawatu for the first time, the Ministry for Primary Industries confirmed today.

The fungus was found on a young ramarama (Lophomyrtus) in a planted area off Victoria Esplanade in Palmerston North.

Myrtle rust response spokesperson Dr Catherine Duthie says operational activity will start immediately to try to contain the disease.

“Hopefully, we have found it in this region early, which would give us a chance of trying to eliminate it or, at least, slow down the spread there. We are swinging straight into action. The infected plant will be removed and securely disposed of and one of our 7 field surveillance teams will begin an intensive inspection of myrtle plants on all properties within a200-metree radius.

“It is disheartening that myrtle rust has been detected in another region, but it is consistent with the expected infection pattern.

“Residents can help, by checking the myrtle plants in their garden. At this time of year, the fungus is still in its sporulation, or spreading, stage. This means it is very visible. Without touching the plant, you can look on either side of the leaves and new shoots for any sign of a bright yellow, powdery eruption. Some leaves could also be buckled or twisted, or look diseased with dry pustules that are grey or brown. It’s really important not to touch the plants or brush against them, as this can disrupt the spores and speed up its spread.”

Suspected cases of myrtle rust can be reported to the biosecurity freephone number – 0800 80 99 66.

The ministry will investigate suspected cases, track and monitor its spread, and collect information to help understand the disease’s impact on New Zealand.

At 19 March, there has been a total of 409 properties affected by myrtle rust on mainland New Zealand: Northland (4 properties), Auckland (63), Waikato (33), Bay of Plenty (92), Taranaki (200), Manawatu (1) and Wellington (16). In the last couple of weeks, most detections have been in Taranaki and Auckland.

There have been no detections in the South Island to date, although north-western areas were identified in climate modelling of being at a high risk from spores carried on the wind from Australia.

Source: Ministry for Primary Industries