Grafted or ungrafted vines? Phylloxera, rootstocks and the purest wine.

The insect that changed wine forever

Phylloxera is a tiny aphid-like insect from North America that feeds on vine roots. When it arrived in Europe in the 1860s, it spread through almost every wine region and killed millions of vines.

American vine species had evolved with phylloxera and could tolerate it. The European wine vine, Vitis vinifera, could not.

The solution: grafting

The answer was to graft European varieties onto American rootstocks. The roots resist the insect, while the grapes above ground remain Cabernet Sauvignon, Pinot Noir or Riesling. Today the vast majority of the world’s vineyards are grafted.

Rootstocks are chosen for soil, drought tolerance and vigor, and they influence how the vine grows and ripens.

Where ungrafted vines survive

Phylloxera does not like sandy soils, and some places were never reached by it. Ungrafted vines still grow in parts of Chile, in sandy vineyards such as Colares in Portugal, on islands like Santorini, in some old vineyards of South Australia and in pockets of Europe such as parts of the Mosel.

Elsewhere, a few winemakers plant ungrafted vines on purpose and accept the risk. Bordeaux’s Loïc Pasquet, whose Liber Pater is the subject of our documentary The Most Expensive Wine in the World, is a famous example.

Are ungrafted wines better?

Supporters say ungrafted vines give purer, more precise wines that express the place better. Critics say the differences come from old vines, low yields and careful winemaking, not from the roots themselves, and that the risk of losing a whole vineyard is huge.

In The Science of Wine, Dr. Jamie Goode visits winemaker Jean-Sébastien Capdevielle, who gambles his crop on ungrafted vines, and a scientist to find out whether it is worth the risk.