How to Combat Esca, the Scourge of Vineyards?

The vine is that marvelous climbing plant that, with every harvest, brings us the pleasure of tasting its fruit and the surprise of its craftsmanship. A marvelous plant, yes, but the vine is fragile.

What on earth is an esca?

No, “esca” isn’t the latest trendy business school, as one might think (ahem ahem), but one of the earliest vine diseases—if not the oldest of them all: quite simply, a fungal disease that causes the vine to wither away! Explanation: basically, this means that fungi take hold in the vine’s trunk. It is therefore a disease that enters through the wood, causing degradation or even complete dieback of the wood; it is a form of necrosis of the backbone of our sacred plant…

There are several fungi that attack them. There are three main ones, dating back to Greco-Roman times! Yes, they’re tenacious, and like all fungi, they thrive in damp conditions and become more active in hot weather. Yum! They do grow, of course, but where do they find their way in to take hold? Well, most often, contamination occurs through large pruning wounds made by the winemaker during a winter that’s a bit too mild and a bit too rainy. From there, the fungi make themselves at home in the wound and thrive throughout the year.

Note: I’m listing the names of these fungi here for anyone who’s interested: Phaemoniella chlamydospora / Phaeocremonium aleophilum / Famitiporia (the one responsible for tinder… don’t worry, we’ll talk more about that later).

Recognizing esca

With a cold, you have a stuffy nose, trouble breathing, and so on. With Esca, it’s the same—symptoms appear fairly quickly, first on the leaves and then on the wood.

• On the leaves: Once the fungi have reached the base of the vine, they block the flow of sap (the vine’s lifeblood), which is supposed to travel to the tips of the leaves to help the vine bear fruit. These leaves then change color (yellow on white grape varieties, red on red grape varieties) and eventually dry out completely; this can sometimes take just a few hours—it happens very quickly—it’s a sudden death!
• On the wood: You were wondering what that tinder was doing up there (yes, you were wondering). Tinder is the spongy white rot caused by fungal growth, which leads to central or localized necrosis of the wood.

Once these symptoms appear, they spread very quickly throughout the vine, and winemakers generally assess the extent of the damage in their vineyards in August following the infection. In France, one of the hardest-hit regions is the Loire Valley, particularly its Cabernet Franc vineyards (4% of the vines there were uprooted in 2012). Savagnin in the Jura is also highly susceptible to esca, and so on.

Let’s stop pulling them out—let’s fight Esca!

Until now, uprooting diseased vines has seemed to be the only way to eradicate esca from a vineyard. However, this drastic measure—just like the preventive use of sodium arsenite, which was banned in 2011—is not the only option! Yes, there are methods to prevent and treat esca, just like wearing a scarf to avoid catching a cold, or taking a Fervex to make it go away.

Prevention can be approached in three different ways:

• Pruning must be done with respect for the vine. That is why, in 1921, René Laffond published *L’Apoplexie*, in which he developed a preventive treatment for Esca (and other wood diseases) using the Poussard pruning method, which redirects the flow of sap back into the vine.
• Preventive measures can also be taken through suckering (the process of removing non-fruiting shoots, known as “suckers”). Many people perform manual or mechanical suckering. To avoid creating large pruning wounds, it is recommended to use pruning shears, which allow for greater precision and thus a smaller opening, preventing necrosis from setting in.
• In the future, it would also be a good idea to provide nursery operators with the necessary resources to analyze and sort contaminated wood—something that, unfortunately, is not currently being done due to a lack of resources…
  
  As for treatment—and this is the point we wanted to make—it’s good to know that there are two ways to treat the problem without having to uproot the vine!
  
• A “surgical procedure”: curettage. This procedure aims to remove (curette) the part of the wood infected with tinder fungus (yes, you know the one). It’s a highly delicate operation, because it involves using a chainsaw to cut into the wood to remove the fungus—with the risk of severing the sap flow that we’re trying to save! When the curettage is done properly, the vine produces grapes again the very next year, and in 99% of cases, the wood heals! (Video below at 5:05)
  
• Since this procedure is very delicate, it is not suitable for severely infected wood that cannot be treated. In such cases, re-grafting can be performed, as in most instances, Esca settles on a vine whose rootstock is healthy (since its purpose is to provide resistance to certain diseases). The procedure involves removing the vine from the rootstock, cutting a slit into the rootstock to insert a new graft! Like any young vine that has just been planted, the re-grafted vine can produce high-quality grapes as early as two years after re-grafting. Even more surprising, the grapes it produces will be as “old” as the rootstock’s roots! This practice is effective in 90% of cases—it’s definitely worth a try! (Video below at 10:06)

It is, of course, difficult to plan these operations when several hectares of a single vineyard are affected by disease, as they require a massive workforce. Nevertheless, this approach offers hope for the diseased vines, whose fate is not necessarily destined for the trash. This perspective is also excellently captured by Denis Dubourdieu in a video (below), without which this article would not have been complete. It is with deep emotion for this great oenologist that this article is published, as Denis Dubourdieu passed away on July 26, 2016. This master of wine shared his knowledge with us, notably helping to revive effective solutions for combating Esca.

Source of the documentation:

Video presented by Denis Dubourdieu and master tailors Simonit & Sirch

Institute of Vine and Wine Sciences

French Institute of Vine and Wine.