An independent review into how the kiwifruit vine disease PSA came into New Zealand has found there were shortcomings with biosecurity systems, but it does not say that caused the entry.
The bacterium has infected 40% of the country's kiwifruit orchards and will cost the besieged industry $410 million over the next five years.
The review commissioned by the Ministry for Primary Industries identified four failures, including that import requirements for kiwifruit pollen were inadequate and processes used to develop them were deficient. It can not definitively say PSA that came into the country on pollen.
The report was issued on Wednesday and says no single person is responsible for PSA entering the country - rather, the biosecurity system as whole did not adequately respond to the risk the disease posed.
The ministry's director general, Wayne McNee, says there may never be answer as to its origins.
"It's possible that it could have come on pollen, it could have come on individuals travelling back and forward, it could have been horticultural equipment, or it could have been smuggled in in plant material. We don't know the answer to that and we may never do so."
Mr McNee says the ministry is considering whether it re-prioritises its resources to manage risks to profitable industries.
The report makes six recommendations, including the Ministry for Primary Industries reprioritising its resources to manage risks facing economically significant industries.
Primary Industries Minister David Carter says the ministry is taking immediate steps to implement the recommendations included in the report.
Mr Carter says he will be monitoring the work closely and expects a progress report within three months.
Meanwhile, the president of the industry group New Zealand Kiwifruit Growers Neil Trebilco says it's considering legal action over the PSA outbreak.