Zespri says some kiwifruit growers, whose crops have been wiped out by the PSA vine disease, are illegally planting a new gold variety.
About 13 hectares of the new variety, which is not cleared for PSA-resistance, has been grafted by growers who did not hold a licence.
Nearly 1000 orchards are now infected, mostly in the Bay of Plenty.
Zespri says the gold variety is one of two recently developed, G3 and G9, that is being monitoring for resistance to PSA.
Grower relations general manager Simon Limmer says several G3 licences were sold to growers last year at a median price of $25,000 per hectare.
He says growers are taking a risk with their plants in using the unproven strain.
Mr Limmer says that when the variety is cleared, they will need to buy licences to grow it.
PSA-V has now infected nearly 1000 orchards, or 28% of New Zealand's kiwifruit orchards.