The "Four Sisters" track in the Waipoua forest in Northland has been closed temporarily due to the discovery of kauri dieback nearby.
The Department of Conservation and local organisation Te Roroa said soil taken near the stand of kauri had tested positive for a kauri dieback pathogen.
The track will stay closed until further notice.
DOC Northern North Island Operations Director Sue Reed-Thomas said closing the track was the best way to protect the kauri stand.
"People should understand that if they access the closed track, and the surrounding site, they are putting our kauri at great risk.
"Waipoua Forest already has limited public access and most visitors use the formed tracks. To help protect the forest's kauri, it's important for visitors to stick to the open tracks and clean their footwear thoroughly before entering and leaving."
Staff from Te Roroa, kaitaki for the forst, conducted the soil sampling in February.
Alan Nesbit, Chair of the Te Roroa Manawhenua Trust, said was it was "extremely concerned" an iconic stand of trees could be affected.