Wine Word: Phylloxera

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Phylloxera is a wine word that has been around since the 1850s when it ravaged the vineyards of Europe, and spread through most of the wine producing world.

Do you know what Phylloxera is? And what it can do to a vine?

Phylloxera is a small aphid or louse (less than one tenth of an inch long) that feeds on the roots of grapevines until it kills the vine. It was first noticed in France in 1853, where it rapidly spread, destroying millions and millions of acres of vineyard. It subsequently spread to almost every grape-growing region of the world.

Phylloxera is believed to have originated in the United States. It was transported to Europe unwittingly on the roots of plants that were being imported into Europe. You see Phylloxera does not kill other plants – only grapevines.

Adult phylloxera lay about 200 eggs each cycle and are capable of up to seven cycles per year. Baby phylloxera move become adults in about eight weeks - this gives you an idea of how quickly the pest spreads.

No Phylloxera Cure: There is no cure for Phylloxera. Once a vineyard is infested, it kills the vines and remains in the vineyard. After much research (and extensive devastation of European vineyards), it was discovered that phylloxera only kiils vines of the vitis vinifera species (also known as European vines). Almost all the grape varieties that make quality wine are of the vitis vinifera species.

American grapevines from other species such as Vitis Rupestris, Vitis Riparia and Vitis Berlandieri are more resistant to Phylloxera. Somehow they have evolved over time and built up a natural resistance. Unfortunately, many wines produced from these species have an unpleasant ‘foxy’ taste.

The Phylloxera Solution - Rootstock Grafting: Finally American scientists suggested grafting rootstocks made from American vines onto vitis vinifera vines. This worked, and so began the practice that continues today of grafting American rootstocks onto European vines as a means to prevent phylloxera attack and spread. See my earlier post on rootstocks, which explains rootstocks in more detail and highlights the evolution of rootstock development, such that today rootstocks are chosen not just for their resistance to phylloxera but also for a host of other viticultural characteristics such as drought tolerance, vine vigor control, earlier ripening and so forth.

Phylloxera Free Zones: While phylloxera destroyed most of the vine growing world, there are a number of ‘lucky’ grape growing regions in the world that have been spared the scourge. Some of them such as the island of Santorini in Greece have escaped because of the high proportion of sand in the soil. For some reason the phylloxera louse cannot complete its lifecycle in very sandy soils.

Other wine producing regions such as Australia’s South Australia and parts of New South Wales have escaped phylloxera, thanks to extreme vigilance, farm gate hygiene and inspection, grapevine sanitation and quarantine regulations to ensure that the louse is not accidentally carried in on grapevine cuttings, vineyard machinery, freshly harvested grapes, grape juice or must or even on the clothes or shoes of vineyard workers from other infested areas.

In Chile it is believed that vigilance along with its isolation west of the vast Andes Mountains, which form a natural barrier from other grape-growing countries, has helped prevent infestation. Argentina has also been spared, though they do not know exactly why! Some believe that the traditional practice of flood irrigation in vineyards has helped drown any unwelcome vine root feeding pests.

While Phylloxera cannot be eradicated, the successful the practice of grafting has enabled grapevine growers to manage phylloxera and contain its devastation potential in vineyards.

(Image credits: Sadovnikova Olga/Shutterstock)

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