Kauri dieback disease has been discovered in the Coromandel - a development that has been described as "serious blow" to efforts to protect the species.
Test results have shown the presence of Phytophthora taxon Agathis (PTA) or Kauri dieback disease in the Whangapoua Forest, just north of Whitianga - the first confirmed case in Kauri-rich Coromandel.
The kauri is a treasured feature of Coromandel, and its own Kauri 2000 movement has seen volunteers plant more than 40,000 kauri across the peninsula since 1999 in an effort to replenish numbers.
Until now, the soil-borne disease has been limited to Northland, the Waitakere Ranges and on Great Barrier Island.
Announcing the case today, Conservation Minister Nick Smith said he was taking a precautionary approach by immediately closing the affected area to reduce the risk of spread.
"It will also enable time to determine the extent of the disease and our on-going management of kauri dieback in the wake of this negative news."
Officials from the Department of Conservation and the Ministry of Primary Industries today briefed local iwi, Coromandel MP Scott Simpson, the Kauri 2000 Trust and local government representatives.
Notice of closure to the 319-hectare Whangapoua Forest/Hukarahi Conservation Area was signed today by Dr Smith using Section 13 of the Conservation Act to take immediate effect.
Kauri dieback disease is caused by a microscopic, fungus-like organism which infects the trees' roots and damages the tissues that carry nutrients and water within the tree, effectively starving the tree to death.
Nearly all infected trees die and there is no known cure, though research is currently underway.
Among the thousands of trees infected so far, two kauri that feature strongly in some of Colin McCahon's artworks had to be felled, and another 23 at the late artist's Titirangi property had also tested positive.
Scientific testing late last week confirmed the presence of the disease from two young kauri in the Whangapoua Forest/Hukarahi Conservation Area.
"Kauri is an iconic species for New Zealand and one of the oldest and largest organisms on earth," Dr Smith said.
"These massive trees define their forest ecosystem and when they die, other species dependent on them are put at risk."
A further problem with the disease was that it killed trees of all ages, including 1000-year-old kauri that were irreplaceable, he said.
Minister of Primary Industries Nathan Guy said not enough was known about the disease and how it spread.
"This detection of the disease is in a forest with no public tracks and little public use other than by some pig hunters," Mr Guy said.
The disease has been in New Zealand since the 1950s and was formally identified in 2008. It is possible it has been in this forest unidentified for years."
He asked the public to do its part to avoid spread of the disease.
"This means adopting biosecurity measures of cleaning and disinfecting footwear, vehicle tyres and machinery when moving to or from any kauri forests. We also urge walkers to keep to formed tracks.
"We need to take a precautionary approach of assuming every kauri stand may be
This detection of kauri dieback was also a setback for the Keep Kauri Standing programme led by MPI and involving DOC, iwi and the four northern regional councils.
"This programme, set up in 2009, was initially established through to June 2014," Dr Smith said.
"It was reviewed last year and we were planning a ramping-up of this work in the next financial year prior to this discovery.
"This work will now need to be brought forward with urgency."
The Government has been criticised for a lack of support and funding commitment in fighting kauri dieback disease. Last year four regional councils made a plea to Mr Guy for more funding.
"After two years of refusing to commit funding to the programme, it is now time for the Government to stump up with the cash," Labour associate environment spokesman Phil Twyford said.
"The kauri is one of the most beloved species and without adequate funding to stop the spread of the disease, the kauri is an endangered species."
Green MP Eugenie Sage was also critical of the Government over the issue.
"The National Government's failure to provide increased and secure funding for both the Department of Conservation and MPI has crippled efforts to battle PTA and slow or prevent its spread."
Research work into the genetics of the disease to identify different strains was "urgently needed", she said.
"The Government's failure to increase the funding in 2012/13 and 2013/14 means MPI, DoC and researchers are starting from way behind in tackling PTA."