Phylloxera threat on the rise

Phylloxera louse (Photo: Department of Agriculture and Food)

Do you go for a walk amongst the vines when you visit wineries? Many of us assume we are free to do this unless there are signs or locked gates. But we should all think twice about doing it, as the phylloxera threat is increasing.

The official phylloxera infestation zone in southern Victoria, which includes the Yarra Valley, has recently been expanded as more outbreaks of the pest have been discovered. The present Victorian phylloxera infestation zones affect the Yarra Valley, Goulburn Valley, and a large area of north east Victoria including the King Valley, Beechworth, Alpine Valleys, Glenrowan and Rutherglen. Most of these have been phylloxera regions since the initial outbreak in the late 19th century, but the Yarra Valley is a recent addition, and also the source of the current spread.

Phylloxera vastatrix, or grapevine phylloxera, is an aphid-like insect which lives on the roots of grapevines, sapping the plant’s growth and eventually killing it. It spreads from vine to vine by crawling through cracks in the soil and between vineyards and regions via soil residues and plant material.

Soil caked on machinery is probably the main risk, but soil on footwear is also a risk, which is why some wineries require visitors to have their shoes chemically disinfected before and after entering a vineyard, or to wear protection over their shoes.

Phylloxera had never been known in the Yarra Valley before the 1990s when it was found in a vineyard in the St Huberts area. It has been slowly spreading outwards from the initial detection site.

Agriculture Victoria recently announced that the Maroondah Phylloxera Infested Zone boundary had been extended to the north, following new detections of phylloxera. The extension was gazetted on March 30. The extension captures four additional vineyards in the Yarra Valley region.

It’s important to note that wine from phylloxera infested vines is not harmful to human health. It is a problem because it can kill entire vineyards and threaten entire regions – as it did in France and other parts of Europe in the late 1800s when it crippled the French wine industry. It took years for a solution to be found. Vines were replanted on phylloxera-resistant American rootstocks on a massive scale.

The fear is that it could happen here on a mass scale. At least we know the solution now, but it is expensive and time-consuming. South Australia has never had any phylloxera, and the great fear is that it could devastate the valuable old-vine resources of that state.

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