Burgundy vines have been set alight to fight against frost
© Etienne Ramousse/Zeppelin/Sipa/Rex/ShutterstockBurgundy vines have been set alight to fight against frost.
Winemakers across France are counting the cost of several nights of frost this week that threaten to decimate grape harvests in some of the country's best-known and prestigious wine-producing regions.

The government is readying an emergency rescue package after rare freezing temperatures that could cause some of the worst damage in decades to crops and vines.

From Bordeaux to Burgundy and the Rhône Valley to Champagne, winemakers were out in their fields on Friday inspecting the destruction.

"It breaks like glass because there's no water inside," said Dominique Guignard, a winemaker in the Graves area near Bordeaux, as he rubbed the first shoots on his vines.

"It's completely dried out, there's no life inside," said Guignard, who heads a group of producers in Graves, which is known for its robust red wine.

Many industry experts say the damage from temperatures of up to -6C may be the worst in decades, partly because the frost followed unseasonably warm weather last week.

"It's a national phenomenon," said Jérôme Despey, the secretary general of the FNSEA farming union and a winemaker in the Hérault region. "You can go back in history, there have been [freezing] episodes in 1991, 1997, 2003 but in my opinion it is beyond all of them."

In the Rhône Valley, the head of the local wine producers' body, Philippe Pellaton, said it would be "the smallest harvest of the last 40 years", with losses of 80-90% compared with normal. Winemakers are "shattered, desperate", he said, with the Côte-Rôtie area particularly badly hit.

In Burgundy, which produces some of the finest white wines in the world, the head of the local producers' association estimated "at least 50%" of this year's harvest had been lost.

The Champagne region was not spared, with the head of the national winemakers' association CNIV, Jean-Marie Barillère , saying there was "a lot of damage".

To ward off frost overnight on Tuesday and Wednesday, farmers across the country lit thousands of small fires and candles near their vines or fruit trees.

Some well-heeled vineyards hired helicopters to try to keep the heat close to the ground.

The burning was so intense in the south-east that it led to a layer of smog over the region, including over Lyon.

As well as vines, growers of kiwis, apricots, apples and other fruit have been badly hit along with farmers of other crops such as beet and rapeseed.

During a visit to the Loire wine-making area, the French agriculture minister, Julien Denormandie, said it was "an episode of extreme violence which has caused extremely significant damage".

The government has declared an "agricultural disaster", meaning it will begin offering financial support to farmers, and Denormandie called on banks and insurance companies to join in the efforts.

He said several hundred thousands hectares of farming land had been hit.

Many winemakers are not insured against the effects of frost because of the cost of the coverage, and many producers were already struggling financially.

The Covid-19 pandemic has depressed demand for wine globally because of the closure of restaurants and bars.

Exports to the US have also been hit by tariffs on French wine imposed by the former US president Donald Trump, while the vital British market has also suffered because of Brexit.

Agence France-Presse in Paris