In November 2010, Psa (Pseudomonas syringae pv. actinidiae) was first discovered in New Zealand.
Plant & Food Research, the country's crown research institute, immediately mobilised a team of more than 100 people, including plant pathologists, breeders and orchard management specialists to tackle the problem.
Their efforts paid dividends last year when kiwifruit marketer Zespri exported $2.3bn of fruit, almost 20% more than the season before Psa was discovered, and is on track to double global sales to $4.5bn by 2025.
A recent report from the University of Waikato forecasts that by 2030, the industry will have created 29,000 new jobs in New Zealand and tripled GDP contribution to more than $6 billion.
“Psa was potentially devastating for the New Zealand kiwifruit industry,” says Dr Bruce Campbell, Plant & Food Research’s chief operating officer. “When the disease was discovered, we knew we had limited time to find the solutions the industry needed to manage the disease and remain viable. Being able to pull together a highly effective team of scientific expertise was paramount
“It was an incredibly stressful time for our scientists, not only in terms of how fast the scientific process was having to deliver answers, but also the emotional impact the disease was having on their friends and neighbours. I’m incredibly proud of how the Plant & Food Research team responded, and this prize really demonstrates the importance of their work to New Zealand.”
Initially, the Plant & Food Research team worked with the industry to contain the spread of the disease by developing new orchard management techniques. The science team also developed diagnostic tests to inform growers’ management decisions and identified agrichemicals that could protect against the disease.
However, a new cultivar was required to support ongoing growth of the industry.
The New Zealand industry had gained significant market growth through the gold kiwifruit cultivar ‘Hort16A’, marketed globally as Zespri Gold Kiwifruit, but this was found to be particularly susceptible to Psa.
When Psa was discovered, a new gold kiwifruit cultivar ‘Zesy002’, referred to by growers as Gold3 and sold around the world as Zespri SunGold Kiwifruit, was in the initial commercialisation phase.
After an intensive screening programme of the hundreds of genetically-diverse varieties from the breeding programme, ‘Zesy002’ was discovered to be tolerant to the disease.
“Identifying a new cultivar is complex, as it has to have the right characteristics to meet grower requirements as well as meet consumer demands for taste,” says Dr Campbell. “Having a cultivar that met these requirements and also had tolerance to Psa was an important step in the industry’s recovery. We screened hundreds of plants to make sure Gold3 was the best option for the industry, we really didn’t want to get that wrong.”
Forty-eight million trays of Zespri SunGold were sold last season, with an export value of $686m.
The Prime Minister’s Science Prize includes a $400,000 prize fund to be used to support the team’s work. This prize money will be used to establish New Zealand as a hub for bioprotection technologies and further the development of new science technologies to protect plants against biosecurity threats.