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Grapevines to get health check
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Grapevines in the Adelaide Hills, Langhorne Creek and Currency Creek wine region will be over the coming weeks as part of an ongoing campaign to ensure the vine-devastating insect phylloxera has not entered South Australia.
While strong quarantine laws and industry vigilance have to date prevented the entry of phylloxera into South Australia, the impact of an outbreak on vineyards and grapegrowers could be significant and long-lasting. The Phylloxera & Grape Industry Board, a wine industry funded body, conducts an annual vineyard surveillance program targeted at the early detection of phylloxera, the tiny insect that has, in the past, devastated vines across the world.
Phylloxera is an aphid-like insect that feeds from the roots of grapevines. Death of the vine is inevitable and infested vineyards must be uprooted and replanted with vines grafted to phylloxera-tolerant rootstocks. Phylloxera is easily transported on nursery material, machinery and vineyard workers clothing and, because it is breeds asexually, only one insect is needed to cause an infestation.
Peter Hackworth, executive officer of the board explained that cutting edge remote sensing and Geographical information Systems technologies are being used. Near infrared aerial imagery is collected and vines that are diseased and show symptoms that could be consistent with phylloxera are identified and then inspected. The technology is so sensitive that a single defoliated vine can be identified, thus providing an opportunity to detect phylloxera and limit the damage to vineyards. Inspection involves remove root samples and examining them under magnification for the tiny insects.
Because South Australia is one of the few major viticultural regions in the world without phylloxera, it has the largest collection of old vines which produce grapes with great concentrations of flavour. Peter explained that phylloxera would be the death of those vines and it would take years for the replacement vines to achieve the same quality consistently. ‘Vineyard owners would be doubly hit; reduced income as vines die and become less productive followed by the cost of removing and replanting with grafted vines’. An independent study commissioned by the Board in 2002 found that if the average vineyard in the Adelaide Hills was stuck by phylloxera, over a 20 year period it would be nearly a third less profitable than if it had remained phylloxera-free.
Inspections have been previously conducted in the Barossa Valley, Riverland, Clare Valley, McLaren Vale, Coonawarra and Padthaway. The inspection teams will visit over 100 vineyards in the Adelaide Hills, Langhorne Creek and Currency Creek wine regions.