As many as 50 kiwifruit growers have been illegally injecting their crops with antibiotics in a desperate bid to stop the Psa bacteria spreading.
But the industry is confident that none of the fruit made it to market after a rigorous testing system and is urging export markets not to be concerned about New Zealand's kiwifruit.
Zespri spokesman David Courtney said the exporter had tested every kiwifruit orchard in New Zealand and 1 per cent of the industry, all from the Te Puke region, had admitted illegally injecting their crops.
"So any fruit that failed that test won't be exported and any orchard that we know has been treated illegally, it's illegal for us to accept that fruit to be sold," Mr Courtney said.
Before this year's harvest in March, a declaration form was sent to every grower which asked them to state that they had either used antibiotic streptomycin spray legally before fruit flowers formed, they hadn't used it at all or they had used it illegally.
The growers were warned that those who did not answer the form truthfully and whose fruit was found to have residue would endure any exportation costs.
Mr Courtney said the small number of growers who did illegally inject their vines admitted their actions.
Te Puke grower Michael Montgomery said he injected 17ha of kiwifruit vines, but has now been banned from selling or exporting his fruit. He told One News that he accepted the practice was illegal.
Kiwifruit growers in the region have been growing increasingly desperate following the outbreak of the bacteria, first identified on New Zealand kiwifruit orchards in November 2010.
At last count, it has cost the industry nearly $900 million.
And a recent report suggested the worst of the vine-killing scourge, which has affected more than 1200 orchards nationwide, would come in the next 12 months and cost 470 jobs annually over the next three years.
New Zealand Kiwifruit Growers president Neil Trebilco said it was disappointing that some growers chose to make that mistake.
In spring last year, the symptoms of Psa disease were rampant in gold vines in Te Puke and growers could see their livelihood was at stake, said Mr Trebilco, a Tauranga grower.
"So some people did some things that were inappropriate. But you can kind of feel for those guys, the fact they were in that situation but unfortunately they've made a bad decision in that case."
As soon as the industry became aware it moved quickly to make sure none of the fruit which was treated illegally made it to market.
"We are more keen than anyone else to ensure none of the infected product gets to market because our livelihood depends on it that it doesn't," Mr Trebilco said.
At the height of the Psa outbreak, growers were allowed under very strict conditions to spray a diluted form of streptomycin on vines before fruit formed but were never permitted to inject it.
The Ministry of Primary Industries confirmed last night that it was investigating the practice.