AUSTRALIA'S wine and table grape industries are facing an escalating biosecurity challenge due to the increasing mothballing, and abandonment, of vineyards.
With winegrape prices so low, significant numbers of vineyard owners - spanning large, medium and smaller operators in all key production regions - are walking out, leaving the vines to tough-it-out, or die.
This is exposing industry to exotic threats, such as Pierce’s disease, which it’s said, ‘would make Phylloxera look like a kindergarten picnic’.
For Wine Grape Growers Australia (WGGA) executive director, Mark McKenzie, this is now a key concern.
“As the season progresses more vineyards are being left and our biosecurity risks escalate, Mark McKenzie says.
“We know that in drier areas if the water’s turned off the vines will die. However, in higher rainfall areas, the vines can persist. But, unfortunately, so too do pests and diseases; these vineyards can become a haven - a sink - for biosecurity threats.”
He says, worse still, should these vineyards be near others, and should an exotic disease or pest arrive and not be seen, industry can have an outbreak on its hands.
“Mothballing or abandoning vineyards – the impact on neighbours and industry is the same. Both mean an increased chance of biosecurity threats if some level of vineyard pest and disease protection is not being implemented.”
WGGA is raising the issue with government agencies.
“We’re initiating dialogue with the states, and we would like to see harmonisation to ensure a basic, consistent level of hygiene and monitoring activity can be implemented.
“But, clearly, it’s beholden upon everyone to increase their vigilance – we just can’t leave this to the authorities.”
“This means growers and vineyard managers continuing to monitor vines for pests and disease, and reporting anything at all unusual. Early detection is the key, which is why abandoned vineyards will continue to be a biosecurity risk,” Mr McKenzie says.
The aggressive pest that acts as a vector for the exotic threat, Pierce’s disease, is edging closer to Australia.
And the glassy-winged sharp shooter (GWSS) is now in French Polynesia and the Cook Islands.
For the Australian wine and table grape industries, this is getting too close for comfort.
It’s the US experience of the ‘sharp shooter’ that has industry so concerned.
Pierce’s disease is caused by the grape strain of the bacterium Xylella fastidiosa, and is spread by piercing and sap sucking insects – namely sharpshooters, leafhoppers and spittlebugs. Pierce’s disease existed in California for at least 100 years, but the introduction of the glassy-winged sharp shooter (GWSS), Homalodisca vitripennis, significantly increased both the rate of spread and severity of the disease, and productivity was dramatically affected.
Australia has not recorded either Pierce’s disease or the vector, and stringent quarantine measures are in place to try and keep both out of the country.
Dr Prue McMichael of Scholefield Robinson and the National Vine Health Steering Committee, says AQIS’ pre-border and border quarantine measures underpin an effective biosecurity effort.
“The second step requires on-farm and regional level biosecurity," Dr McMichael says.
“We can’t rely only on border control. Everyone in the grape industry needs to be alert and actively involved in surveillance so if something does slip through, we have the best chance for early detection, containment and/or eradication.
“So, to keep us free of the disease and its key vector, we need to have a prevention mindset.”
The industry is becoming more aware of the benefits of:
• Regularly checking planting material and its sources, vineyards, and surrounding vegetation.
• Making casual and full-time workers, and vineyard visitors, aware of biosecurity measures, and minimising the risks associated with vehicle and equipment sharing and movement.
Dr McMichael also says that even without the GWSS, Pierce’s disease remains a threat.
“There are some native Australian insects that may transmit this bacterium, which has various strains and can infect a range of plants, including almonds, some stone fruit, citrus and woody ornamentals,“ she says.
Many in the grape industry believe the single biggest threat for introduction of exotic diseases, is still the illegal importation of planting material.
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