How to fight against the Esca, the scourge of the vines?

The vine is this marvelous liana that offers us, at each harvest, the pleasure of tasting and the surprise of a know-how. Wonderful plant yes, but fragile is the vine. Subject to a lot of bad weather already (which we have not stopped talking about this year), the vine can also, like any living organism, get sick. There are dozens and dozens of diseases that can affect the vine, such as esca, unfortunately back in our vineyards for a few years! 3, 2, 1, Description and cure!

What is esca?

No, esca is not the latest fashionable business school as one might think (ahem ahem), but one of the first vine diseases, if not the oldest of all: simply a cryptogamic disease causing apoplexy of the vine! Explanations: basically, it means that fungi settle in the vine. It is thus a disease which arrives by the wood, causing a degradation, to see a complete decline of this last, it is a form of necrosis of the spinal column of our sacred plant...

The fungi that attack it are several. We count 3 main ones, finding their origins in the Greco-Roman period! Yes, they are tenacious, and like all the mushrooms, they develop under moisture and are accentuated under strong heats. Yummy! They develop, of course, but where do they find the entrance door to settle? Well, most often, the contamination is done by big wounds of size, made by the wine grower during a winter a little too soft and a little too rainy. From then on, the fungi take their place in the wound and develop throughout the year.

NB : I give the names of these mushrooms for those who are interested : Phaemoniella Chlamydospora / Phaeocremonium aleophilum / Famitiporia (responsible for tinder... don't worry, we will talk about it later).

Recognizing esca

For the common cold, you have a blocked nose, difficulty to breathe, etc. For Esca, it's the same, symptoms can be observed quite quickly, first on the leaves, then on the wood.

• On the leaves: The fungi having reached the foot, they block the path of sap (the blood of the vine) which is supposed to go to the end of the leaves to make the vine fruitful. These leaves then become colored (yellow on white grape varieties, red on black grape varieties) to finally dry up completely, it can sometimes take a few hours, it is very fast, it is apoplexy!
• On the wood: You were wondering what tinder could do above (yes, you were). Tinder is the white spongy rot resulting from the development of the fungus, which causes central or sectorial necrosis of the wood.

These symptoms, once observed, will spread very quickly on the whole vine and, in general, the winegrower observes the extent of the damage on his vineyard in August following the contamination. In France, one of the most affected regions is the Loire and its cabernet franc (4% of the vines were uprooted in 2012). The Savagnin in the Jura is also very sensitive to esca, and so on.

Let's not pull out anymore, let's fight against esca!

Until today, the uprooting of diseased vines seems to be the only solution to eradicate esca from a vineyard. However, this radical solution - just like the preventive arsenite of soda, banned in 2011 - is not the only one! Yes, there are methods of prevention and cure against esca, such as putting on a scarf to avoid the common cold, or taking a Fervex to make it go away.

Regarding prevention, it can be done in three different ways:

• Pruning mustbe respectful of the vine. This is why in 1921, René Laffond published L'Apoplexie in which he developed a preventive treatment of Esca (and other wood diseases) by the Poussard pruning which allows to position the return of the sap path in the vine.
• We can also work on the prevention of Esca by pruning (operation which aims at eliminating the non-fruiting branches, called "gourmands"). Many practice manual or mechanical pruning. In order to avoid creating large pruning wounds, it is recommended to use pruning shears, which allow more precision and therefore less opening, preventing necrosis from taking place.
• In the future, it would also be good to allow nurserymen to have the necessary means to analyze and sort out the contaminated wood, something which is unfortunately not done at present, for lack of means...
  
  As for the cure, and this is where we wanted to come to, it is good to know that it is possible in two ways, without having to pull up the vine!
  
• A "surgical operation": curettage. This operation aims to eliminate (curettage) the part of the wood contaminated by the tinder (yes, you know). This operation is very delicate, because it is done with a chainsaw by digging into the wood to remove the fungus, the risk being to cut the flow of sap that we are trying to save! When the curetage is properly done, the vine will give again grapes the following year, and in 99% of the cases, the wood will heal! (Video below at 5:05)
  
• This practice being very delicate, it does not concern the seriously affected wood, inoperable. We can then resort to a regrafting, because in most cases, the esca settles on a foot whose rootstock is healthy (since its function is to be resistant to certain diseases). The maneuver consists of removing the vine from the rootstock, cutting a slit in the rootstock to insert a new graft! Like any young vine just planted, the regrafted vine will be able to produce quality grapes as soon as 2 years after the regrafting. Even more surprising, the grapes they will produce will have the "age" of the roots of the rootstock! This practice remains efficient in 90% of the cases, it's worth a try! (Video below at 10:06)

It is of course complicated to think of these operations when several hectares of the same vineyard are affected by the disease, the labor being extremely important. Nevertheless, this look is a hope for the sick woods, which finally do not have for only future the dustbin. This look is also excellently reported by Denis Dubourdieu in a video (below) without which this article would not be complete. It is with an emotional thought for this great oenologist that this article sees the light of day, because Denis Dubourdieu left us on July 26, 2016. This wine artist shared his knowledge with us, contributing in particular to bring back to the forefront nice solutions to fight against esca.

Source material:

Video presented by Denis Dubourdieu and the Simonit&Sirch master pruners.

Institute of Vine and Wine Sciences

French Institute of Vine and Wine.

Mélany Bachmann (wine merchant)