Kauri dieback disease has been found in a forest on a private property at Tairua, on the Coromandel Peninsula.
Waikato District Council said it was the sixth place on the peninsula where the disease has been found.
It has already been confirmed at five locations in Hukarahi, near Whitianga, and in the Whangapoua Forest.
Council spokesperson Patrick Whaley said staff were working with the landowner to prevent the spread of the disease.
Earlier this month the Department of Conservation reclassified kauri, one of the world's largest and longest-living tree species, as a threatened species due to the spread of dieback disease.