ALL that orchard hygiene does is buy you time to come up with other solutions.
So said plant disease expert, Dr Bruce Campbell at last month's Australian Banana Industry Congress at the Gold Coast.
Dr Campbell was the chief operating officer of plant and food research in New Zealand during the outbreak of Pseudomonas syringae pv. actinidiae, (Psa) a disease which crippled the lucrative kiwifruit industry in 2010.
Dr Campbell led a team of more than 100 scientists who conducted an intensive screening program leading to the discovery of SunGold kiwifruit, a Psa tolerant variety.
The swift commercialisation of the cultivar effectively saved the country's kiwifruit industry.
Dr Campbell shared his insights with the Australian banana industry in the hope of passing on some advice in dealing with Panama disease Tropical Race 4.
"It's clear that you've understood this completely but it's not a bad thing to feel vulnerable to some of these things because it focuses you on being prepared to be able to respond," Dr Campbell said.
Psa is a "tiny disease but it spreads very quickly", resulting in spotted leaves, cane dieback and liquid oozing from plants.
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"As a grower, this would be unbelievably hard to watch," Dr Campbell said.
"The reality is, if we look forward with the knowledge we dug up from actually working on this problem, there are a lot of things that are raised that we still need to be actively considering and continuing to feel vulnerable in the industry."
When the news broke of the disease's presence, Dr Campbell said there was a huge flurry of interest and concern for the industry, plus plenty of finger-pointing.
"There was this huge kind of pressure to come up with the answers quickly," he said.
The company, Zespri, essentially acts as a single-desk marketer for New Zealand kiwifruit.
He said it was a wake-up call for its emergency protocols as it had a response plan written for fruit fly, not Psa.
"They had a strategic plan but that went into the bin at the first board meeting," Dr Campbell said.
The New Zealand government established a $50m fighting fund called Kiwifruit Vine Health (KVH).
Dr Campbell said this enabled his team to pull together key scientists who were working on other things.
Like TR4, Psa spreads rapidly on things such as vehicles, which caused the team to quickly shift to a response phase as opposed to resistance.
"The horse had very much bolted," he said.
The three broad areas of research and development covered were:
- Understanding the disease
- Managing the disease
- Searching for new cultivars.
A target was set at two to three years to come up with a solution. The was judged to be the amount of time the financial institutions would be sympathetic to growers and the industry.
"Increasingly it switched the focus to science being the solution. It was actually very nice but incredibly scary for the scientists who had to deliver it," Dr Campbell said.
Against the habits of many experienced scientists who worked on achieving a 95 per cent confidence level, the process of going from a trial variety to a commercial process was sped up even if that meant promising varieties were not completely resistant.
"It's not for the fainthearted. It's very 'big numbers' research," he said.
In about 2013, the decision was made to go with SunGold.
Dr Campbell said one blessing for the industry was that grafting kiwifruit was a relatively simple process and the new variety was attached to cut-down original rootstock.
Zespri has since released numerous licences for the new varieties.
In 2016/17, 48 million trays of Zespri SunGold were sold with an estimated export value of $686 million, up 70pc on the previous year and increasing by around 10 million trays a year as newly-grafted vines reach production.
In 2018, Dr Campbell received the NZ Prime Minister's Science Prize for his leading role in the new variety's development.
"It was a good opportunity to show science step up and show it can provide a viable option," he said.
He did caution though that more work would be needed to fight copper resistance and that farm hygiene would become increasingly paramount.
His advice for the banana industry in the face of TR4 was:
- Be prepared and be respond rapidly.
- Underpin your industry with really strong science
- Buy time with orchard hygiene and controls
- Manage risk through genetic diversity
- Be united