Pseudomonas syringae pv. actinidiae (Psa) is a bacteria that can result in the death of kiwifruit vines. Psa carries no risks associated with human or animal health and does not affect plants other than kiwifruit vines. Psa is believed to be spread by weather events, namely wind and rain, and plant material. It is also believed to be spread by footwear, vehicles and orchard tools. In an orchard it can exist as:
Growth of the bacteria outside/inside the vines can result in leaf spotting, cane/leader dieback and, in extreme cases, vine death accompanied by the production of exudates.
Source: Kiwifruit Vine Health (KVH) http://www.kvh.org.nz/about_psa
In New Zealand, Psa was first officially reported on a kiwifruit orchard in Te Puke on 5 November 2010 at 4.30pm, though there were known instances of it well before this official date. Initially there was hope from the then Ministry of Agriculture and Forestry (MAF) and growers that the bacteria could be contained within the Bay of Plenty region, however a domino effect saw the bacteria spread around the country, multiplying quickly with an ability to devastate a crop in less than a season. Given a downturn on other horticultural prices, the hit to kiwifruit was particularly strong for growers - because, for many, kiwifruit had become their mainstay. New Zealand now suffers from two to three distinct isolates of Psa - an Italian and an Asian strain.
With what should have been strict border regulations, imposed by Biosecurity NZ itself, there was huge speculation as to how Psa entered New Zealand.
In 2012, the Ministry of Primary Industries (MPI) commissioned an independent report into Psa by Sapere Research Group. The report identified major shortcomings with Biosecurity NZ’s import requirements and border processes.
The plaintiffs allege that Biosecurity NZ was negligent, causing at least $885 million worth of losses to kiwifruit growers around the country, and had no real respect to the threat of Psa to New Zealand. In our view, no concerted effort was made to assess the strategic threat that Psa posed to the New Zealand kiwifruit industry.
In 2010, Zespri launched a $50 million emergency funding package for the immediate effects of Psa, with $25 million being contributed by the Crown. But with MPI's independent report conservatively estimating $885 million of losses, $25 million is just a tiny fraction of the damage by Biosecurity NZ‘s alleged negligence.
Amidst claims that the kiwifruit industry has now recovered four years later, growers and post-harvest orchardists are still reeling from the effects. It’s not just direct financial losses – growers lives have been destroyed as a result of Psa, and the alleged negligence of Biosecurity NZ.
Legal expert, Professor Bill Hodge, has spoken about the claim saying "they’ve got chapter and verse," noting the claim's legal documents suggest the source was "well-known, and thus identifiable and preventable." See his official statement here.
For more information, check out the Kiwifruit claim Questions and Answers.