A kiwfruit orchard in Whangarei has tested positive for Psa - the first confirmed case of the vine-killing disease in the region.
Since the bacterial disease was first discovered in New Zealand in 2010, about 85 percent of the country's kiwifruit orchards have been affected.
It is estimated to have caused $885 million worth of damage for growers.
Kiwifruit Vine Health chief executive Barry O'Neil said all growers in the region have been informed about the test result, and are being urged to keep a close eye on their orchards.
"What we don't know is whether Psa could be present in other orchards in the region. We are undertaking monitoring activity of adjourning orchards over the weekend to get a better understanding of the situation."
Mr O'Neil said the symptoms found - dieback and exudates (secretions) - meant it was likely the disease had been in the area for some time.
He said a meeting of growers would be held next week to discuss the issue.
There are 49 orchards, which together have a total of 144 canopy hectares, in the Whangarei region.
Growers in every region are being advised to monitor their vines and maintain a robust spray programme this spring.