The kiwifruit industry says it does not know how a case of the more virulent Italian strain of the vine disease PSA has flared up outside the containment zone near Te Puke.
The new instance of the disease has been found 15 kilometres outside the zone.
The industry is about to begin harvesting but it says measures are in place to avoid the disease spreading further.
The president of New Zealand Kiwifruit Growers, Peter Ombler, says the orchard with PSA is isolated and it is a mystery how it became affected.
It probably wasn't wind-assisted, he says, because it is too far away from the containment zone.
Mr Ombler says that despite the ongoing PSA problem the harvest is looking positive.