Kiwifruit disease Psa confirmed in Australia

October 15 , 2018

Two weeks after Seeka (NZX: SEK) reported bacterial symptoms reminiscent of kiwifruit disease Pseudomonas syringae pv actinidiae (Psa) in an Australian orchard, Agriculture Victoria has confirmed the tests came up positive.

The state’s chief plant health officer Rosa Crnov issued a statement to Fresh Fruit Portal stating there had been a confirmed detection of “PSA biovar 2 or 3” in the orchard in Bunbartha, near Shepparton.

“PSA 2 or 3 is an aggressive form of PSA and can kill susceptible kiwi fruit vines. Agriculture Victoria is working closely with New Zealand authorities and the affected business,” Crnov said.

“Agriculture Victoria is following standard biosecurity processes in response to this detection. If you have any concerns about your kiwi fruit or vine health, please contact the Plant Protection team,” she said. 

A spokesperson for the state government agency added that PSA 3 was just another name for the virulent strain Psa-V that is found in New Zealand as well as Italy, France, Portugal, Chile, China, Japan and South Korea.

However, as the diagnosis points either to PSA 2 or 3, scientists cannot be sure whether it’s the same strain found across the Tasman. According to information from Kiwifruit Vine Health (KVH) in New Zealand, prior to this detection PSA 2 was only known to exist in South Korea. 

Having experienced the devastation the cankerous disease wrought in New Zealand, after spotting symptoms Seeka pulled out 4.5 hectares of two-year-old vines around the detection zone.

Shortly after the announcement today, the company issued a statement on the New Zealand Stock Exchange. 

“Seeka Limited [NZX:SEK] advises the market that the Australian Regulatory Authorities have confirmed PSA on the Seeka orchards in Australia, affecting 4.5 hectares of its 154 hectares of kiwifruit orchards,” the group confirmed. 

“Seeka has moved to contain the outbreak and is working with the Agriculture Victoria and the relevant Australian Federal Authorities. Seeka continues to proactively monitor the orchards, and in particular the orchards in development.

“There has been no significant deterioration from the update of October 2nd and no change to the earnings Guidance provided by Seeka.”

Seeka Australia is one of the country’s largest kiwifruit growers with 154 hectares planted, of which 93 hectares are in production with the green Hayward variety that is not as susceptible to Psa, while 61 hectares are in development with different cultivars.

The recent Psa detection was made in one of Seeka’s development plots in a non-producing part of the orchard.

In a statement given to Fresh Fruit Portal, Seeka CEO Michael Franks explained what the impacts of the incursion might be on the Australian kiwifruit industry.

“Firstly we believe that the Australian environment and climate will not be conducive to PSA specifically because the extreme heat in summer,” Franks said.

“It is likely that it will be prevalent in the spring which is probably why we have found it now in our monitoring processes. 

“Seeka has significant orchards in development in Australia and we will now reset the varietal mix in the orchards we are developing there. So really the impact will be a slower time to production than we were planning.”

He added normal containment protocols had been in place since the detection, with “high hygiene” and Seeka’s own restrictions on plant movement. 

“Rather than pulling orchards and plants out – we are cutting the fruit scion off the rootstock and then monitoring the rootstock for signs of infection and managing the area with a targeted spray program,” he said.

A milder form of the disease than New Zealand’s Psa-V was first detected in Australia in 2011, and the situation across the Tasman prompted a strict approach to importing plant material or pollen that might affect the crop.

These measures included only allowing pollen from countries or areas proven to be free of Psa, as well as longer post-entry quarantine for kiwifruit tissue cultures and dormant cuttings, with the latter requiring hot water and surface sterilization treatments.

When asked about how the disease could have arrived, Franks said all plant material introduced to Seeka’s orchard in Australia had come from Australia.

Following the recent food tampering scandal in Australia with strawberries, Victorian authorities and Seeka have been careful to emphasize to the Australian public that the incursion is not a food safety or human health issue. 

Photos: Seeka Australia

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