Work is underway in Northland's Waipoua Forest to determine just how close kauri dieback is to Tāne Mahuta and whether the forest should be closed.

A young kauri was confirmed with kauri dieback just 59m from Tāne Mahuta in May, prompting a team of five scientists, with experts and kaitiaki from local iwi Te Roroa, and support from the Department of Conservation to collect soil samples now the weather has improved.

A rāhui (prohibition) to the forest was not "off the table" but Te Roroa science advisor Taoho Patuawa said more information was needed before making a decision which could have "massive implications for western Northland".

SIMON SMITH/FAIRFAX NZ Dr Ian Horner of Plant and Food Research is leading a team of scientists undertaking soil samples around Tāne Mahuta.

"The rāhui is still on the table but we are trying to get more info on the table."

The implications of closing the forest, a popular tourist attraction, are significant agrees Te Roroa Trust general manager Snow Tāne.

​This includes trying to manage security along a State Highway which runs through the forest.

Further areas of the forest may need mitigation including raising boardwalks or restricting access depending on the results of the scientific testing, Tāne said.

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Northland Inc regional promotions and tourism general manager Paul Davis said closing Waipoua Forest would have an economic impact, especially on the Kauri Coast and Hokianga.

"But Northland Inc understand and agree that protection of the Kauri giants must come first, whatever the economic impact.

"The Waipoua forest and especially Tāne Mahuta is an iconic attraction for Northland's visitor industry.

"The forest is strategically important for our tourism industry as visiting the forest encourages visitors to circulate around Northland, dispersing visitors to the less populated parts of the region."

Kauri dieback is carried in soil spores and infects trees through their root system - while the soil sampling won't confirm whether trees are infected, the work will provide a map of where the disease is in the soil.

It will take a month before the results are known, but the work which is expected to be completed on Wednesday, is the first step in determining future research initiatives in the forest including terrain and soil mapping as well as aerial surveys set down for November.

Plant and Food Research scientist Dr Ian Horner who alongside Dr Ross Beaver from Landcare Research diagnosed kauri dieback in 2006, said there are some "very sad areas" of the Waipoua Forest.

Horner is the lead scientist in the team collecting soil samples at Waipoua.

"It's upsetting seeing these thousand, perhaps couple thousand year old trees turned into these big skeletons," Horner said.

"I'm extremely worried it could infect Tāne - there's no reason why Tāne Mahuta would be immune from the disease."

Horner said the team are collecting soil samples in grids within 200m of Tāne.

There are noticeable signs people have been climbing off the boardwalk, said.

"Visitors to the tree are not a problem as long as they stay on the track - the only danger is when people climb up and start wandering off the track and potentially spreading the disease.

"People who do that can kill trees unnecessarily."

Horner said injecting infected trees with phosphite was providing some respite in rickers, but there are still a few unknowns about treating larger, older trees.

Senior scientist at Plant and Food Research Dr Nick Waipara, alongside kauri dieback advisor Lee Hill and Snow Tane (Te Roroa Trust) spotted a diseased tree back in May, just 59m to Tāne Mahuta.

Waipara said an expedition in 2010 confirmed the disease was 500m away from Tane Mahuta, and in 2013 another infected tree was confirmed within 100m of the kauri giant.

The tree discovered in May prompted further testing.

Snow Tane said large kauri trees have already succumbed to the disease close to the road, where there's been lots of human impact.

"There's no problem if people stay on the track - it's why we have Te Roroa ambassadors at the tree to encourage good behaviour in such high risk ecological areas," Tāne said.

Tāne said there is hope as more research is conducted into phosphite injections and traditional rongoa Māori healing methods.