Scientists begin work this week in Northland's Waipoua Forest to see how close kauri dieback has crept to Tāne Mahuta.
The soil-borne pathogen has already killed trees within 100 metres of Tāne and other forest giants including Te Mātua Ngāhere.
Depending on what the scientists find, their work could mean the forest, one of Northland's key tourist attractions, is closed to the public to protect the trees.
Dr Ian Horner, from Plant and Food Research, is leading the team that begins work today in Waipoua.
The plan was to track the kauri dieback pathogen in the soil - and find out how far it had spread.
Soil sampling would show exactly where the pathogen was in relation to the big trees, Dr Horner said.
"We'll be taking soil samples on initially a sort of a grid pattern, certainly between where that infected tree was found and the big tree, but also in quite a wide grid around there to try and do a detailed map of where it is.
"Because until we know that it makes it very hard to manage."
Kauri have been dying in Waipoua for years according to iwi.
Local iwi, Te Roroa, have been asking for some time for clear information on how bad the infection is and how best to tackle it.
Snow Tāne, the manager of the Te Roroa Trust, said the iwi was braced for bad news.
But that was better than not knowing the risk to the big trees, he said.
The Department of Conservation (DOC) and the iwi have in the past pondered the best course of action: The tracks and boardwalks in Waipoua are of a high standard and should prevent visitors from tracking spores of the fungal disease to the iconic trees.
But some visitors have a habit of going rogue.
This year one group left the boardwalk and made a beeline for Tāne Mahuta to give him a farewell hug, to the horror of Te Roroa's vigilant ambassadors, who successfully intercepted them.
One dilemma DOC and Te Roroa were worried about was that people would find their way to the iconic trees even if the tracks were closed.
"The impact of closing it will be felt throughout Northland and we understand that, but we need to make the decisions based on the best possible outcomes for our local rākau rangatira or for our big trees," Mr Tāne said.
Mr Tāne said the results of the soil sampling near Tāne Mahuta should be known within a couple of months. An aerial survey in November would give an overview of what was happening.
Meanwhile, a Far North hapū is urging whānau to think hard about whether pig-hunting is compatible with kauri health.
Ngātirua, manawhenua of Mangonui Forest, hoisted a hui at the weekend at Taupō Marae. The hapū has been working with the Kauri Rescue Project, involving scientists, landowners and iwi.
Hapū member Waitangi Wood said because pigs and people spread the disease, the tradition of pig hunting now had to be weighed up against other traditions.
"We don't only just use the forest for pigs, we use the forest for other things as well - our words, our histories, our stories, our traditions are all linked to our forests.
"We could keep pigs but lose forests, but in losing forests we lose our identity, Ngātirua will not be Ngātirua."
Some whānau were tackling kauri dieback with traditional knowledge and rongoā (medicine).
It was vitally important they monitored the trees and documented the results, Ms Wood said.
Dr Horner seconded that.
"I think it is worth pursuing these things and who knows what might be revealed, there might be something that really is a magic cure."
After five years of trials, injecting the trees with phosphate had been shown to halt kauri dieback, and healed lesions in young trees, Dr Horner said.
But finding a dose that would work safely for big trees - let alone enormous ones like Tāne Mahuta - was still some way off.