Phylloxera - WikiHQ

thumb|Galls made by D. vitifoliae on leaf of [[Vitis sp.]]

Grape phylloxera is an insect pest of grapevines worldwide, originally native to eastern North America. Grape phylloxera (Daktulosphaira vitifoliae <small>Fitch 1855</small>) belongs to the family Phylloxeridae, within the order Hemiptera, bugs); originally described in France as Phylloxera vastatrix; it is equated to the previously described Daktulosphaera vitifoliae and Phylloxera vitifoliae. The insect is commonly just called phylloxera (; from , leaf, and , dry).

These almost microscopic, pale yellow, sap-sucking insects, related to aphids, feed on the roots and leaves of grapevines (depending on the phylloxera genetic strain). On Vitis vinifera, the resulting deformations on roots ("nodosities" and "tuberosities") and secondary fungal infections can girdle roots, gradually cutting off the flow of nutrients and water to the vine. Nymphs also form protective galls on the undersides of grapevine leaves of some Vitis species and overwinter under the bark or on the vine roots; these leaf galls are typically only found on the leaves of American vines.

American vine species (such as Vitis labrusca) have evolved to have several natural defenses against phylloxera. The roots of the American vines exude a sticky sap that repels the nymph form by clogging its mouth when it tries to feed from the vine. If the nymph is successful in creating a feeding wound on the root, American vines respond by forming a protective layer of tissue to cover the wound and protect it from secondary bacterial or fungal infections.

right|thumb|Phylloxera eggs inside a leaf gall

Many attempts have been made to interrupt this lifecycle to eradicate phylloxera, but it has proven to be extremely adaptable, as no one stage of the lifecycle is solely dependent upon another for the propagation of the species.

Fighting the "phylloxera plague"

thumb|left|180px|"The phylloxera, a true gourmet, finds out the best vineyards and attaches itself to the best wines."<br>Cartoon from [[Punch (magazine)|Punch, 6 Sep. 1890)]]

In the late 19th century, a phylloxera epidemic destroyed most of the vineyards for wine grapes in Europe, most notably in France. Phylloxera was introduced to Europe when avid botanists in Victorian England collected specimens of American vines in the 1850s. Because phylloxera is native to North America, the native grape species are at least partially resistant. By contrast, the European wine grape V. vinifera is very susceptible to the insect. The epidemic devastated vineyards in Britain and then moved to the European mainland, destroying most of the European grape-growing industry. In 1863, the first vines began to deteriorate inexplicably in the southern Rhône region of France. The problem spread rapidly across the continent. In France alone, total wine production fell from 84.5 million hectolitres in 1875 to only 23.4 million hectolitres in 1889. Some estimates hold that between two-thirds and nine-tenths of all European vineyards were destroyed.

In France, one of the desperate measures of grape growers was to bury a live toad under each vine to draw out the "poison". In the same department, where the canal irrigation system built by the Romans still partly persists to this day, winter flooding is also practiced where possible, for instance south of the city of Tarascon. Flooding the vineyards for 50 days kills all the nymphs that overwinter in the roots or the bark at the bottom of the plant.

Some regions were so blighted by phylloxera that they never recovered, and instead the producers switched crops entirely. The island of Mallorca is one example, where almonds replaced vines.

Vines that survived phylloxera

right|thumb|A collection of vines with grafted rootstocks

According to wine critic and author Kerin O'Keefe, due to tiny parcels of vineyards throughout Europe that were inexplicably unscathed, some vineyards still exist as they were before the phylloxera devastation.

So far, most Chilean wine grapes have remained phylloxera free. Chile is isolated from the rest of the world by the Atacama Desert to the north, the Pacific Ocean to the west, and the Andes Mountains to the east. Phylloxera has also never been found in several wine-growing regions of Australia, including Tasmania, Western Australia, and South Australia. Australia has strong internal biosecurity controls to minimise the risk of phylloxera spreading beyond 'Phylloxera Infested Zones' in parts of Victoria and New South Wales. The Riesling of the Mosel region has also remained untouched by phylloxera; the parasite is unable to survive in the slate soil.

Until 2005, three tiny parcels of ungrafted Pinot noir that escaped phylloxera were used to produce Bollinger Vieilles Vignes Françaises, one of the rarest and most expensive Champagnes available.

A rare vintage port is made from ungrafted vines grown on a small parcel, called Nacional, in the heart of the Quinta do Noval. Why this plot survived is unknown.

Bien Nacido Vineyard in Santa Maria Valley AVA of Santa Barbara, California, is a phylloxera-free vineyard. Despite being planted on its own roots, with UC Davis virus-free clones, the vineyard has never been affected by phylloxera. The high percentage of sand in the soil creates a mostly uninhabitable substrate for phylloxera. While Bien Nacido has not been affected, a potential infection remains, as all of the vines are true V. vinifera without scions or grafting. Many of the old vines were planted in 1973 and fall within the blocks G, N, Q, and W. The wines of Bien Nacido Estate have a high percentage of these ungrafted and phylloxera-free vines within the cuvée.

Colares vineyards, native to the Portuguese region of Sintra, are grown on 3–4 metres of sand, so are unaffected by phylloxera.

References

External links

Phylloxera and Grape Industry Board of South Australia 2011
The Vine's Enemy: Phylloxera Vastatrix Profile drawn from The Oxford Companion to Wine Third Edition, p.521

Fighting the "phylloxera plague"

Vines that survived phylloxera

References

Further reading

External links