Northland's iconic giant kauri tree Tāne Mahuta has been checked and cleared of kauri dieback disease although two sites in the wider area have again tested positive for the pathogen — with one just 60m away.
Waipoua Forest kaitiaki Te Roroa and the Department of Conservation (DoC) confirmed on Thursday new test results indicated the area in the immediate vicinity to Tāne Mahuta was clear of Phytophthora agathidicida (PA).
However, two sites located about 60m and 90m away were positive for the pathogen.
Te Roroa science and research manager Taoho Patuawa said the test results validated the need for further protection measures to continue within the forest.
He said it would also help to make an informed decision on the future of the Tāne Mahuta walkway — which has remained open, with extra measures in place to prevent the spread of kauri dieback.
"I am pleased that no sign of the disease has been detected any closer to the rangatira [chief] kauri tree Tāne Mahuta, but the risk still remains," Patuawa said.
The soil sampling was conducted by scientists at Plant and Food Research and staff of Te Roroa, after consultation with DoC, from October 8-10 to establish how close the disease was to Tāne Mahuta.
In total, 104 samples were taken on a 200m by 200m grid. This included a ring of seven samples taken about 2m from the base of the trunk of Tāne Mahuta, where PA was not detected.
Two samples taken about 60m and 90m away from Tāne Mahuta tested positive for PA. Both sites were no closer to Tāne than the site confirmed with the disease in June this year and were not publicly accessible.
"After discovering kauri dieback near Tāne Mahuta earlier this year, we avoided a knee-jerk response and took a carefully planned approach, using available science to detect the spread of the pathogen in the immediate area surrounding Tāne Mahuta," Patuawa said.
"We also acknowledge the support of DoC and Biosecurity New Zealand who have been working in partnership with us to protect one our most significant and symbolic taonga tuku iho.
"It is still vital that all visitors to Waipoua respect our wishes to stay on the track and clean their footwear when they visit and leave the forest," he said.
DoC director of the Northern North Island Sue Reed-Thomas said more monitoring would be done to ensure the risk of the disease was managed.
"We'll continue to pour all our energy into restricting the spread of the disease, with the Tāne Mahuta Response Plan as our guide. A five-year pig control programme for Waipoua Forest will be underway shortly to move pigs out of core areas and where the disease is nearby," Reed-Thomas said.
"The Tāne Mahuta site has long been one of the most protected areas in the country from kauri dieback, with boardwalks, cleaning stations and members of Te Roroa as ambassadors in place. It's important for everyone to stick to the boardwalks and clean their footwear thoroughly before entering and leaving Waipoua Forest."