Grape phylloxera is an insect pest of grapevines worldwide, originally native to eastern North America.

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).

[2] Currently there is no cure for phylloxera and unlike other grape diseases such as powdery or downy mildew, there is no chemical control or response.

In the late 19th century the phylloxera epidemic destroyed most of the vineyards for wine grapes in Europe, most notably in France.

The intent of the cross was to generate a hybrid vine that was resistant to phylloxera but produced wine that did not taste like the American grape.

[citation needed] In the EU they are generally banned or at least strongly discouraged from use in quality wine, although they are still in widespread use in much of North America, such as Missouri, Ontario, and upstate New York.

The use of resistant American rootstock to guard against phylloxera also brought about a debate that remains unsettled to this day: whether self-rooted vines produce better wine than those that are grafted.

The Juan Garcia variety remained—untouched by phylloxera—sheltered on the vineyards planted on the man-made land terraces along the mountainous skirts on the gigantic and steep Duero Arribes / Douro River Canyon, where the microclimatic conditions discourage the growth of phylloxera.

To escape the threat of phylloxera, wines have been produced since 1979 on the sandy beaches of Provence's Bouches-du-Rhône, which extends from the coastline of the Gard region to the waterfront village of Saintes Maries de la Mer.

[8] 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.

It 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.

[11] 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.

[12][13] The Riesling of the Mosel region has also remained untouched by phylloxera; the parasite is unable to survive in the slate soil.

[14][15] 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.

[16] A rare vintage port is made from ungrafted vines grown on a small parcel, called Nacional, in the heart of the Quinta do Noval.

Large swaths of vineyards on the slopes of Sicily's volcano Mount Etna also remain free of phylloxera.

In this environment (> 400m AMSL), the surface water from heavy bouts of rain seals the soil so perfectly that it drowns phylloxera before they are able to thrive.

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