Producers in Bordeaux, France's largest wine-growing region, warn they are facing heavy losses this year due to mildew. As many as 90 percent of local vineyards are affected by the fungus, which winemakers blame on wetter, warmer conditions created by climate change.
The damage is unprecedented, says Stéphane Gabard, president of the association of Bordeaux's AOC ("appellation d'origine contrôlée", or protected designation of origin) wine producers.
"The chamber of agriculture estimates that 90 percent of plots are affected," he told FranceInfo news radio on Wednesday. "The damage ranges from a few percent of vines to 100 percent, where output is completely wiped out."
A few weeks ahead of the main harvest, Gabard warned: "Production in Bordeaux will once again be down."
Wine growers have been warning of a mildew "epidemic" since late June, when a combination of high temperatures and heavy rains led to a proliferation of the fungus.
"The vine leaves stayed damp for much of the day. Those are ideal conditions for mildew to grow," said Gabard.
Known as downy mildew, the fungus leaves yellow patches on vine leaves and causes young grapes to wither.
'Subtropical' weather
The problem has also struck several other wine regions in the south of France, including Dordogne, Gers, Lot-et-Garonne and Pyrénées-Atlantiques, but the Gironde area of Bordeaux appears to be worst hit.
Local MPs have called on the national government to declare an "agricultural disaster", a move that allows producers to claim compensation from the state for climate-related losses.
Rather than its usual oceanic climate, Gabard says, the weather in Gironde has been practically "subtropical".
"For two months it's felt like Martinique over here," another local wine grower, Mikaël Cousinet, told L'Express magazine in mid-July.
Uncertain harvest
France's grape harvest is due to begin in late August, peaking in September.
In its first official forecast, released on Tuesday, the agriculture ministry predicted that this year's overall wine output would be in line with the average, partly thanks to promising seasons in the Champagne and Burgundy regions further north.
But it is not yet clear how much damage mildew has done in Bordeaux and the south-west, the ministry warned. Meanwhile it said the south-central region of Languedoc-Roussillon has been hit by persistent drought.
According to the previsional forecast, France is on track to produce between 44 and 47 million hectolitres of wine in 2023, compared to 45.4 million in 2022.