The French Government has promised to help winegrowers in the Bordeaux region, some of whom lost their entire crop in storms at the weekend.
Cyril Giresse, who runs the Chateau Gravettes Samonac in the Cotes de Bourg appellation, said hailstones "the size of pigeons' eggs" destroyed grape buds and left vines bare.
"The storm lasted only 15 minutes, but in some places, there's nothing left," he said, "just the vines stripped as if the grapes had been picked."
Jean-Dominique Chateau, another producer, said: "I've got nothing left. I've been growing grapes for 33 years and this is the worst storm I've ever seen. Last year we lost 40 per cent of our crop to hail but this year it's even worse."
Stephane Travert, the agriculture minister, said: "We'll take the necessary measures and we're ready to meet Bordeaux winemakers."
Franck Jullion, of the producers' association in the Blaye Cotes de Bordeaux appellation, said: "It's as if the vines had gone back to winter. Estates hit by frost last year will not recover. We're going to need a lot of support and solidarity."
Saint-Emilion, one of the most prestigious Bordeaux appellations, was spared, but parts of Medoc were badly hit, as were Cognac brandy producers in Charente and Charente-Maritime.
Didier Gontier, director of the Cotes de Bourg appellation, said: "This is going to affect two years of production."
Bordeaux is France's largest wine-growing area, with 300,000 acres of vineyards producing 700 million bottles, from table wines to some of the most famed and expensive vintages.