"The heat on the vines is not a tragedy": heatwave, drought, what impact on the wines of Charente-Maritime?

With climate change, temperature variations are set to increase. How are winegrowers managing this? Example in two Charente-Maritime estates

It's no secret that heatwaves and drought have hit Charente-Maritime at the beginning of August. Extreme temperatures are rarely a boon for crops, and the vines have had to endure this heat. At temperatures above 35 degrees, the vines begin to suffer. Yves Lageat, winemaker at the Pique Russe estate in Gourvillette, reports some of the difficulties. "For us, the risk is burns. We have to monitor and be careful not to tie the vines too tightly, keeping the small branches to provide shade for the fruit. Because the heat can stress the vines, hinder grape ripening, and lead to a drop in yield or even a thickening of the grape skins."

Located between Le Couarde and Saint-Martin-de-Ré, the Arica estate , created in 2018, is protected by the particularly mild climate of the Île de Ré. No heatwaves for them. Even if the temperatures rise during the day, they drop back down at night. "As for droughts, we are really privileged on the island. Our land is ventilated. The wind is very salty here, it's one of the characteristics of the wine we produce, it's an asset. So instead of fearing sunburn, it's salt burn that we watch out for."

“The selection of plant material is essential to avoid low yields.”

Although protected for the moment, the winemakers of the Rétais estate, Marine and Simon, are not losing sight of future risks. "It's true that when we planted our crops, we were careful to choose rootstocks that were more or less sensitive to heat and had a greater capacity to absorb water. The selection of plant material is essential to avoid low yields."

Indeed, some grape varieties are more or less resistant to high temperatures. Older grape varieties are known to withstand extreme temperatures, low or high, but are more prone to diseases that develop with humidity. Some are choosing to return to them in view of climate change, whereas they had been left aside when diseases ravaged crops until the end of the ^19th century .

Both the Arica estate and the Pique Russe estate are certified organic . This environmentally friendly and sustainable cultivation method allows the vines to avoid stress and to have a better yield. Freshness is found deep in the soil. Young shoots are therefore more likely to suffer from the heat because they are less rooted than older ones. "We work the land with machines that cut the roots at the surface, those that develop at the ends. In this way, the vine has no choice but to root down. We don't give it a choice," explain the winegrowers from Ré.

Every year, at the beginning of June, winegrowers remove the leaves from the vines. "This step is very important because the position of the leaves has a real impact on the grapes. We cut the leaves on the side facing the rising sun, this way the humidity from the night and morning evaporates with the morning sun when it is weaker. This helps prevent the development of diseases that thrive in a humid environment. This year, we cut less, we left this cap of leaves which allows more shade on the grapes," say the winegrowers of the Île de Ré.

"Over the year as a whole, we had a good balance between water and heat, so the impact of droughts will be low."

To maintain coolness, Marine and Simon decided to keep the grass covered 100%. The goal is to create shade on the ground and keep it cool. Biodiversity is fully operational. "You might think it's counterproductive because during heatwaves, plants compete for access to water, but we've only observed benefits with this technique," say Marine and Simon of the Arica estate.

"Over the year as a whole, we had a good balance between water and heat, so the impact of droughts will be low compared to our colleagues further south . Here in Charente-Maritime, we're lucky. And, above all, the heat on the vines isn't a disaster," assures Yves Lageat. "The problem is if it lasts. We still have some room for maneuver in the department; we can still play with the shade. But further south, the vines are already much drier."