There are no plans at the moment to close the walkway to the world's most famous kauri and other iconic trees in Waipoua Forest.

Nor will Tane Mahuta, New Zealand's biggest and oldest tree, be dead within a year, as claimed by some who accuse the Ministry for Primary Industries (MPI) of not acting quickly enough to protect it from kauri dieback.

According to a Lincoln University study, one in three kauri tested at all sites have shown signs of dieback disease (Phytophthora agathidicida), and Waipoua Forest could be the worst affected of all.

Dr Amanda Black, a member of the university's bio-protection research team, predicted recently that Tane Mahuta would be infected within a year, which has since been incorrectly repeated as dead within a year.

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A Department of Conservation spokesman said there was no evidence that Tane Mahuta was infected, and if it was, because of its size, deterioration would occur over many years, not months.

However, DoC confirmed that the Lord of the Forest was at risk because of its proximity to infected kauri in a separate catchment, which had been actively managed for many years. Dieback was first discovered in Waipoua in 2010. Now lesions have been seen on another tree in that catchment, about 160m from Tane Mahuta.

The spores of the kauri phytophthora are primarily spread through water and soil.

Contaminated and little-used tracks to other Waipoua kauri have been closed to the public, but DoC believes the Tane Mahuta boardwalk and cleaning station are of a standard that should not enable the disease to spread, as long as visitors comply.

"The Tane Mahuta site is one of the most well-mitigated areas in the country, and is protected by boardwalks, cleaning stations and ambassadors monitoring and managing for the risk. We are confident that the risk of further spread due to human vectors is low in this forest," a spokesman said.

When the disease settles in soil at a kauri's base it enters through the root system, making its way into the trunk and branches. Trees effectively starve to death over a period of several years. There is no known remedy.

DoC is working with the MPI, local iwi Te Roroa and other stakeholders to ensure the Waipoua risk is managed. Te Roroa met with experts specialising in kauri dieback recently, to discuss protection measures for the culturally significant site.

For the foreseeable future, the response will comprise ongoing testing, monitoring and pig control, and visitor education.