Myrtle rust has been confirmed in Bay of Plenty town Te Puke, in the first find outside the main infection area in Taranaki in weeks.
The Ministry for Primary Industries (MPI) said tests had confirmed the plant disease in a 25-year-old ramarama in a private residential garden.
The find brought the number of cases across New Zealand to 46. MPI said a team was removing the plant, spraying the area with fungicide and doing a thorough check of the property.
"Our preliminary talks with the property owner have not found any obvious link with the situation in Taranaki or Northland, and there have been no recent nursery plant introductions to the garden," an MPI spokesperson said.
"This lends weight to the possibility that this new location is a wind-borne infection."
In Taranaki, meanwhile, Manukorihi Golf Club has been closed for the second time in two weeks because of the fungus, forcing the postponement of its club championships.
The golf course was shut down until further notice on Friday, following an investigation by MPI.
Two weeks ago the club had to close while two mature pōhutukawa trees infected by the fungal disease were removed from the grounds.
The fungal disease - originally from South America - was discovered on pōhutukawa trees on Raoul Island, 1100km north east of New Zealand in April.
Other species affected so far include ramarama, lophomyrtus, eucalyptus, mānuka and monkey apple, but MPI has warned it also has the potential to affect bottlebrush, feijoa, guava, and all other members of the myrtaceae family.
MPI said anyone with a suspected sighting should immediately get in touch.
In Australia, the disease was first detected in 2010 and has spread throughout the country, and has killed large numbers of native trees from Northern Queensland to Tasmania.