Waikato Regional Council is warning people to stay away from two kauri trees being tested for kauri dieback, a fungal disease.
The trees, which were planted at Woodstock Primary School in Fairfield about 40 years ago, are cordoned off.
Kauri dieback, which can kill a tree by infecting its roots, is so far confined to Auckland and Northland.
The council says test results are expected to take six weeks and steps have been taken to prevent the disease spreading.
People can help by staying on formed tracks in areas where there are kauri.