The cattle disease Mycoplasma bovis has been found on a farm in the Northland region for the first time.
The ministry says the infected property is a dry stock beef farm, the Ministry for Primary Industries (MPI) says.
It was identified in Northland through the tracing of animals' movements from known infected farms.
Northland Rural Support Trust co-ordinator Julie Jonkers said the farm was one of two that had been on watch for the disease, and the diagnosis was not a surprise.
The trust was working with the family running the farm and it was difficult for the farmers involved.
The confirmation brings to 36 the number of farms actively infected with the disease.
A further 30 farms which were infected have been cleared of their stock and declared safe to repopulate.
Mycoplasma bovis can cause lameness, mastitis and abortions in cows,
It was first detected by the MPI in New Zealand in 2017.
In May the government announced it would try to eradicate the cattle disease, ordering about 152,000 cows to be culled in an phased programme that is expected to take one to two years.