Planning and prevention are our best defences

The emergence of the kiwifruit disease Psa was a hard lesson for the industry. Photo / Warren Buckland.

An outbreak of foot and mouth disease would cripple New Zealand's economy, but how prepared are we?

In 2001, Britain was gripped by the most devastating foot-and-mouth disease outbreak the developed world has known. It changed the agricultural landscape. A strong pound and rising property prices convinced many farmers who had lost their herds - and some who hadn't - to simply give up farming.

The public, most of whom were exposed to images of a national disease response for the first time, were appalled at the slaughter, the restrictions on tourism, and the resulting £8 billion cost to the local and national economy.

New Zealand is fortunate that it has never had an outbreak of foot and mouth. We have some of the strictest border biosecurity in the world, yet the recent emergence of theileria in cattle, and Psa in kiwifruit, reminds us we are not immune to disease introduction.

Sooner or later, despite our best efforts, foot and mouth is likely to enter the country. Cattle, sheep and deer herds will be slaughtered to eliminate infected animals. Tourism will cease as trails crossing farmland are closed to prevent the disease spreading. Half our export market will evaporate instantly. We will lose an expected $10 billion from our economy.

Ministry of Agriculture and Fisheries staff pile the dead pigs on to the fire on the Dennis farm, after a suspected case of foot and mouth disease. It was a false alarm.

What may save us is how up to date our data on livestock is. This is where we face real risk. Farmers provide data on what livestock are where, and how they are moved around the country. Data collection takes considerable effort, as any farmer who has tried to update their FarmsOnLine records, or enter their NAIT (National Animal Identification and Tracing) movements, will know.

Yet without this information we are paralysed during an outbreak and unable to take advantage of powerful analysis and prediction technology. The UK experience serves as a reminder: complacency in keeping livestock data up to date delayed the tracing of movements of infected animals, allowing foot and mouth to spread widely and escape local control measures.

New Zealand's livestock databases are in many cases out of date, leaving us open to a catastrophic failure of our New Zealand brand.

Foot and mouth disease is likely to hit New Zealand at some time.

As a lifestyle farmer and researcher I believe our responsibility is to ensure our records in FarmsOnLine and NAIT are up to date. If there was an outbreak, I'd rather know sooner than later that my newly purchased calves had been on an infected farm. The Government must continue to uphold its end of the bargain, ensuring data is easy to submit and kept private, and guaranteeing against its use for reasons other than disease prevention.

So, if foot-and-mouth disease entered New Zealand tomorrow, would we be ready to respond? The answer now is no. Instead, we wager precariously on the belief that border biosecurity is enough; reality says it isn't and cannot be.

What we learned from PSA

The kiwifruit canker disease caused by the bacterium Pseudomonas syringae pv. actinidiae (Psa) was first reported in Italy in 2008. In two years it had been detected in most of the world's kiwifruit growing regions. Although its precise route of entry into New Zealand remains unknown, Psa's impact on the kiwifruit sector is clear: up to $885 million in losses over 15 years.

The threat of diseases spreading globally is greater for agricultural industries reliant on crops with limited genetic diversity. In New Zealand the kiwifruit industry staked much of its fortune on a single cultivar of gold kiwifruit (Hort16A), which happened to be especially vulnerable to Psa.

Crates of Zespri at on the wharf at the Port of Tauranga. Photo / Bay of Plenty Times

Although the industry is now recovering, the hard lessons learned cannot be forgotten or the next outbreak - whether in kiwifruit, another agricultural commodity or native species - will catch us unprepared.

We simply cannot afford to be ignorant of the biosecurity threats outside New Zealand. Although government, industry and scientific organisations were all aware of the emergence of Psa in Italy, there was a failure to communicate and translate this into more stringent import requirements and biosecurity regulations.

Psa was also known to infect green kiwifruit as early as 1984, yet pathogen resistance was not given enough attention during the development of new gold cultivars. Obtaining a better understanding of vulnerabilities in current crops should inform the identification of risks.

Though the outbreak exacted a heavy toll, we have gained insights into the nature of the pathogen. Whole genome sequencing of a broad set of Psa isolated from 1984 until the present has revealed unexpected diversity. Although the latest outbreak was caused by a single lineage, other strains of Psa are capable of causing kiwifruit disease.

There are also signatures of the exchange of genetic material between these different strains of Psa, as well as with other bacterial species. The most striking implication of this is that new variants of Psa are likely to arise. New cultivars of kiwifruit must be evaluated for their resistance to multiple evolving threats, rather than focusing exclusively on a single lineage of Psa.

Isolation has been a defining force shaping New Zealand's unique environment, but we have entered a new era of globalisation and must prepare for the challenges ahead. Though initially caught off-guard by Psa, government and industry supported the establishment of new collaborations and international forums for the communication of research findings, which will hopefully endure.

New Zealand's success in protecting our agricultural industry and natural resources from future disease outbreaks also depends on whether fundamental research on plant pathogens continues to be supported beyond times of acute need. The best victory is secured without needing to fight a single battle.

• Dr Chris Jewell, Lecturer in biostatistics at Massey University's Institute of Fundamental Sciences

• Dr Honour McCann, Postdoctoral Research Fellow at Massey University's New Zealand Institute for Advanced Study