Nearly all the commercial wines of the world, wherever the grapes are grown, are made from European grape varieties cultivated since Roman times. They all belong to the family Vitis vinifera.
French varieties such as Chardonnay, Merlot, Cabernet Sauvignon and Pinot noir are hugely popular with grape growers and winemakers throughout the New World as well as in other European countries. Several non-French varieties, such as Barbera, Riesling, Sangiovese and Alberino can also be found in remote corners of the wine-world like New Zealand and Argentina.
The reason these varieties are so popular is that they are capable of making good wines that consumers like to drink. They are also quite productive and consistent from one vintage to the next.
However, European grapevines have several flaws when it comes to diseases and pests.
European grapevine flaws
People may have heard of the phylloxera plague which wiped out almost every vineyard in Europe when the insect was unknowingly brought to Europe from North America on the roots of native American vines.
This was not the only problem imported from North America. Powdery and downy mildew (oïdium and mildiou in French) also made it across the Atlantic in the 19th Century. Both these fungal diseases are now worldwide annual problems for wine-growers.
Powdery mildewJonathan Hesford
As well as the mildews, there are a host of diseases that affect European grapevines to a greater or lesser degree depending on climate, location and particular variety. Some are fungal, some bacterial and some viral.
The list is long but includes Botrytis, Grapevine yellows (flavescence dorée in French), Black rot, Excoriose leaf-spot, Eutypa, Black goo, Pierce’s disease and ESCA.
The reason the European grapevine is susceptible to so many diseases is that plants have no immune system, unlike animals. The only way they develop resistance or tolerance to diseases is through evolution. The vine therefore has no inbuilt protection to newly-introduced diseases from other countries or from evolution of the disease.
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The European grapevine was cultivated, selected and cross-fertilised to produce the best wine grapes long before these diseases spread. They are propagated by cuttings to maintain the unique flavours of the variety. There is therefore very little genetic variation in a particular variety. Merlot vines with identical DNA can be found in vineyards in South America, Australia and California, all grown from cuttings from a French vine.
Furthermore, grapevines live for decades and growers strive for consistency, therefore vineyards are some of the most disease-susceptible cultures on Earth.
Without chemical protection, the diseases cause devastating crop losses to European vines, especially powdery and downy mildew, the latter being able to destroy the whole crop in a few weeks if left unchecked. Despite organic producers and their retailers claiming not to use chemicals, they have to spray sulphur compounds to protect from oïdium and copper-sulphate for mildiou on a regular basis every year.
Non-organic grape-growers have access to more modern synthetic protective chemicals requiring fewer treatments and better protection but only a tiny number of intrepid (or crazy) growers don’t use some form of chemical spray intended to kill the fungal disease or prevent it from reproducing.
With an increasing focus on reducing pesticides and chemical sprays, as well as a realisation that fungal diseases can develop resistance to certain synthetic sprays, a lot of research has taken place to try to find more ecological solutions.
Organic disease-tolerant grape varieties
While the organic industry have promoted the use of expensive and dubiously effective ‘natural’ protectants like orange oil, milk powder, talcum powder and teas made from horsetail and nettle, one area which has not received much attention until recently is the development of disease-tolerant grape varieties. Perhaps because the sales of those alternative treatments is very lucrative.
We know that native American grapevines of the Muscadine and other families are genetically resistant to mildews. However, their grapes don’t make very nice wines. Early attempts to cross American and European vines resulted in similarly poor-tasting wines, which is one reason that the French authorities prohibited their use for making wine.
European governments, authorities and voters are pretty much against the use of Genetic Modification (OGM) to develop disease-resistant varieties, therefore the work has to follow slow and imprecise methods of cross-pollination and selection, meaning the research has taken decades to arrive where it is today and focus has only been on resistance to downy and powdery mildew, not any of the other fungal diseases or viruses.
Until 2022, no disease-tolerant varieties were permitted in any Appellation. In the last few years, a lot of progress has been made by researchers, nurseries and forward-thinking producers to encourage the authorities to permit plantings of new hybrid grape varieties, albeit under very strict limitations.
There are currently about 25 disease-tolerant hybrid varieties authorised for use in wine production, none of them provide total protection but they do mean that protective spraying can be reduced to once or twice per year. Most of these plants were developed in Switzerland and Germany, meaning that the varieties are not that suited to the climate of southern France (or Spain or Italy).
They tend to produce wines with more floral or vegetal aromatics and less depth than French varieties. The whites can be compared somewhat to Muscat, Sauvignon blanc and Ugni blanc and the reds to Cabernet Franc and Grenache.
In my experience of tasting these wines, they resemble Eastern European country wines. However, it is early days and the producers who have led the way tend to be those focused on making wines at entry-level prices where the disease-tolerance offers a benefit to yields, especially in wet years.
Very few high-end wineries have experimented with hybrid grapes. The question is whether the consumer is willing to try wines from new varieties, even though they represent major ecological advantages.
One of my neighbours planted a promising variety called Souvignier gris but unfortunately could not get his négociant clients to buy it because they only want to sell commonly-known varietals.
My own costly experiment with it suggested that it is not suited to the dry soils and heat of the Roussillon. The best wines that I have tasted from research wineries have been made from hybrids that have poor, inconsistent yields. I also feel that the organic sector of the industry has little interest in supporting a move which would remove (or reduce) the need for any vigneron to spray any chemicals, organic or synthetic, as pesticide use is their major selling-point.
It is a shame that Genetic Modification has such a bad name outside the scientific world. Progression towards disease-tolerant grapevines would have been much faster and better if the public, and their political representatives, were not so hung up on the fear-factors.
Jonathan Hesford holds a WSET Level 3 and a Postgraduate Diploma in Viticulture and Oenology from Lincoln University, New Zealand. He is the owner and wine-maker of Domaine Treloar in Roussillon.
