An article written in collaboration with Philippe Guilbert, from the magazine Land of Touraine
The winegrowers of Indre-et-Loire pushed a sigh of relief this Wednesday noon: despite the negative temperatures in places last night, no vineyard seems to have suffered significant damage. Fortunately, the air was dry. The association of frost and humidity in the atmosphere is indeed the worst enemy of vines.
It is precisely because there was no humidity in the air that the wine-growers of Montlouis-sur-Loire decided not to take off the helicopters which they sometimes use to warm the atmosphere. above the vines. This means of protection is very expensive and is only used in extreme cases.
On the other hand, the wind towers installed in many Touraine vineyards were triggered automatically : when the mercury drops below a pre-programmed temperature, these small wind turbines circulate the air to heat it. Likewise, many winegrowers have used sprinkling to protect the buds.
Sprinkling consists of watering the vine so that a gangue of ice forms around the bud, the temperature of which is therefore kept at zero. However, this device cannot be implemented everywhere: A large reserve of water (the Loire or the Vienne for example) and soils capable of receiving up to 40 cubic meters of water per hour for 5 or 6 hours, several consecutive days. Only filtering alluvial terraces are suitable: for all these reasons, only the Burgundy and Chinese winegrowers use sprinkling.
The winegrowers of Indre-et-Loire will still be on the warpath next night. Then the temperatures should go up a bit. Despite everything, it will be necessary to wait around May 10 to consider that the vines are definitively immune to a freeze.