28th April 2010, 02:09 PM
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|  Kauri killing fungus| Tane Mahuta threatened| New Zealand
Kauri fungus found near forest giant - Environment - NZ Herald News Quote:
Toxic kauri fungus found near forest giant
By Eloise Gibson
4:00 AM Wednesday Apr 28, 2010
There are fears for New Zealand's most famous kauri, Northland's Tane Mahuta, after a deadly and infectious tree disease was found less than 500m from it.
DNA tests on a sick tree in the popular Waipoua Forest have revealed it is infected with Phytophthora taxon Agathis, or kauri dieback - a fungus-like infection that has been creeping through the remnants of ancient kauri forests.
Even more worrying to scientists is that the disease has also been found in a 600-year-old kauri in the nearby Trounson Kauri Park, a surprise finding that proves trees up to 1000 years old, with trunks 2m in diameter, could be at risk.
"It really does recalibrate our fears," said Landcare research scientist Stan Bellgard, who was part of the team that confirmed dieback in the Waipoua, Trounson and Raetea Forest in Northland.
"Up to this point we had seen it on ricker trees up to about 80cm [diameter] in the Waitakeres."
Dr Bellgard and Stephen King, of the Waipoua Forest Trust and Te Roroa iwi, want Government agencies to step up efforts to protect the home of Tane Mahuta before it is too late.
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Te Roroa manages the Waipoua Forest with the Department of Conservation.
Until this week, councils and Government departments fighting the spread of kauri dieback had hoped to keep the disease out of Waipoua, where many of the country's tallest and oldest kauri live.
The area is in line to become New Zealand's next national park, and the only national park north of Taupo.
Mr King said Te Roroa kaumatua had long seen trees showing symptoms of kauri dieback but scientists have only just developed the necessary DNA tests to confirm it.
He was frustrated the department had been slow to replace walking tracks with boardwalks to prevent people walking over tree roots, and said it was doing little to kill off wild pigs that were trampling infected soil through the forest.
"It has meetings after meetings of talking about it but actually does very little," he said.
DoC spokeswoman Hilary Aikman said the pigs were an important resource to locals and it was not yet known how big a role they played in spreading the disease. "That is something we'll be looking at."
She said work was well under way to pull up the forest's network of gravel tracks and replace them with boardworks. "Clearly we are worried about Tane Mahuta and we'll do anything we can to protect that tree," she said.
The results are the first trial of a system Landcare Research is developing to confirm the presence of dieback.
The next stage is to survey the most iconic and at-risk forests to find out how many trees are infected.
Scientists do not yet know how to treat kauri dieback.
Ms Aikman said traditional fungicides such as those used on avocados and other commercial crops were not appropriate for kauri forests on conservation land because of the potential effects on other plants and animals.
Dr Bellgard said ancient kauri trees were "part and parcel of New Zealand's culture".
Run-down trees that were stressed by drought, water-logging or trampled roots were more likely to become sick, he said.
As well as being carried in soil, scientists believed dieback could be passed root-to-root from infected to healthy trees.
| Kauri-killing fungus found near iconic giant Tane Mahuta | NATIONAL News Quote:
A kauri-killing fungus has been found infecting a kauri tree just 500 metres from the iconic giant Tane Mahuta in the world-renowned Waipoua Forest in Northland.
This is the first time that the pathogen phytophthora taxon Agathis (PTA) has been confirmed in the forest and it puts the kauri Tane Mahuta and other nearby giants at risk of being attacked by the pathogen.
Previously, the nearest PTA had been found to Waipoua was at Trounson Kauri Park, one kilometre south of the Waipoua Forest boundary, where it had been recovered from the soil in 2005.
Landcare Research scientist Dr Stan Bellgard believes increased efforts are required to ensure Tane Mahuta does not fall victim to the pathogen.
Bellgard and his team were guided into Waipoua Forest by Te Roroa kaumatua Davy Paniora and Stephen King of the Waipoua Forest Trust who were able to show scientists trees in the forest that exhibited classic PTA dieback symptoms.
As well as finding PTA close to Tane Mahuta, the team found some other concerning discoveries.
Many of the infected trees discovered to date on Great Barrier Island and near Auckland have been rickers, young regenerating trees up to about 200 years old. However, at Trounson Kauri Park PTA was recovered from a two metre diameter large tree, at least 600 years old.
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Team member Dr Nick Waipara from the Auckland Regional Council says they had discovered a similar-sized infected tree in a survey at the Cascades Park near Auckland. The fact that such large trees are becoming infected confirms the possibility that the iconic giants are at risk, he says.
PTA was also found in Raetea Forest to the north of Waipoua, an old kauri logging area planted with kauri in the 1950's.
Department of Conservation scientist Tony Beauchamp has inspected many of the Northland forests for symptoms of PTA and says it could have been introduced into this area at the time of planting although further sampling is required before this can be verified.
Symptoms of the disease caused by PTA include yellowing of foliage, canopy thinning, girdling of the lower branches and the eventual death of the tree. However, its most distinctive symptom is the excessive bleeding of gum from lesions in the bark near the base of the tree trunk, Bellgard says.
"We were shown some trees near Tane Mahuta with suspicious symptoms and detailed work has confirmed that one tree with characteristic 'pus-like gummosis' was infected with PTA. This is of particular concern because the tree is so close to Tane Mahuta."
Landcare Research scientists have been working with colleagues in Scion, Plant & Food Research and the Auckland Regional Council to investigate the threat posed by PTA since it was discovered on the mainland in 2006. Project leader Dr Ross Beever says there is still a lot to find out about PTA.
"It is a bit of a sleeper. It was first recognised on Great Barrier Island in 1972 but was undoubtedly more widespread even then.
"While it is highly pathogenic to kauri, we know very little about how it spreads and infects trees in the wild. We suspect it is exotic, and are investigating it relationships with strains from overseas, especially South East Asia and Queensland."
Present evidence suggests PTA is a soil-borne disease with long-lived resistant spores that can spread by soil movement, and short-lived swimming spores that can be moved in water flow in soil as well as spreading tree to tree through close contact of the roots.
Soil containing the long-lived spores is likely to be transported around on human footwear and by animals such as pigs.
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