A few select European wines are sold as:
“produced with grapes from ungrafted rootstock”
Ever wondered what that means? Let us tell you!
Vitis Vinifera, the common Europe wine grape, has between 5,000 and 10,000 varietals. Of these, only a few account for nearly all European wine production (we posted about the lack of grape diversity previously).
The current method for growing vines in Europe relies on grafting Vitis Vinifera onto the rootstock of North American vines. A small number of wines are produced using grapes from “ungrafted” vines, but these are usually phenomenally expensive.
Grafting is time consuming and can be difficult. So, why don’t we use ungrafted vines for all European wines?
The short answer is, we can’t.
Grape phylloxera, the scourge of vineyards, makes the use of ungrafted vines impossible almost everywhere in Europe. This tiny relative of the aphid feeds on the roots of grapevines, sucking the sap from them. The resulting damage leaves the vine susceptible to disease.
Grape species native to North America, such as Vitis Labrusca, have developed some resistance to phylloxera. The roots of American vines can secrete a sticky sap that clogs the mouths of phylloxera. If the insect manages to cut into the roots of American vines then once they have moved on the vine can grow a layer of tissue over the wound to prevent bacterial or fungal infection.
North American vines are equipped to defend themselves against phylloxera. However, Vitis Vinifera is not.
French colonists tried to grow Vitis Vinifera in North America in the 16th Century but the vineyards inexplicably failed. Discovering the cause was made all the more difficult by the behaviour of phylloxera. Once the roots have lost a large percentage of sap the pest moves on. Usually, this is before the vine shows any signs of distress. Digging up a dying vine will not likely reveal any of the insects in the roots.
It was subsequently assumed that European vines simply couldn’t be grown in North America. Nobody could understand why.
In the 19th Century it became common practice to import exotic non-native plants into Europe. This was very much a feature of the Victorian era, with Botanists excitedly experimenting with growing plant species gathered from far away places.
With the advent of steamships, crossings of the Atlantic could be carried out in record time. Hence, it is thought that phylloxera began to survive the crossing in the roots of North American vines imported into Europe.
Of course, the inevitable happened, and European wine making was forever changed by what became known as the Great French Wine Blight of the 1850s. That century somewhere between 66% and 90% of all vineyards in Europe were destroyed by the ensuing phylloxera epidemic.
The only known method found to combat phylloxera was proposed by two French wine growers, Leo Laliman and Gaston Bazille, in the 1870s. This technique, namely rootstock grafting, is still in use today. European vines are grafted onto the roots of North American vines. This allows the vines to produce fruit as normal and the roots to have some chance of surviving phylloxera.
A few vineyards did escape the phylloxera epidemic and now produce the only examples of European wines as they were before the epidemic. These ungrafted vines produce grapes which are made into very expensive wines, such as Bollinger’s Vieilles Vignes Françaises Champagne, and Quinta do Noval’s Nacional Vintage Port.
The debate about whether or not grafted or ungrafted vines produce the best grapes is still ongoing to this day.
Image is “Phylloxera cartoon“. Licensed under Public Domain via Wikimedia Commons.