Bordeaux’s Worst Mildew in Memory to Reduce Wine Output

The outbreak of downy mildew hitting the vineyards of Bordeaux this year may cut wine grape production in the growing area by at least a fifth.

In the northern Aquitaine region, which includes Bordeaux, almost all inspected vines had mildew, a weekly report on grape health showed. More than half of grape clusters in affected plots showed signs of the microbial disease, and a third of grape berries in those bunches were tainted.

The numbers for affected vineyards (96%), tainted clusters (58%) and grapes with mildew (35%) suggest potential grape production for Bordeaux may be cut by at least 20%.

Bordeaux produced 4.5 million hectoliters of wine in 2022, a smaller-than-average vintage, data from France’s Agriculture Ministry shows. A drop of 20% versus 10-year average production of 5 million hectoliters would result in one of the region’s smallest vintages of the past decade.

Bordeaux wine sales totaled €3.5 billion in 2020, according to the local wine board. That suggests local winemakers may face at least €700 million in damage from mildew this year.

Worst in memory

The Gironde agriculture chamber earlier this month said mildew affected at least 90% of vines in the Bordeaux area, after weeks of unusually warm and humid weather. The chamber said the outbreak was the worst in memory for winemakers.

Downy mildew (“mildiou” in French) develops at temperatures between 11°C and 30 °C, with its thermal optimum around 25 °C, according to French crop-protection industry organization Phyteis. The disease first spreads on vine leaves, and grape berries are sensitive to mildew until the onset of ripening.

The agriculture ministry plans to release its first estimate of France’s wine production on Aug. 8, with comment on trends in growing regions. The ministry typically provides a regional breakdown in September.

Bordeaux vineyard prices have fallen in recent years, as some of the region’s less prestigious areas struggle with lackluster demand. That’s even as average prices for wine property in France have risen to record levels.