Cognac vineyards face uncertain harvest as drought and rain risks threaten grape yields

The Cognac region is facing a critical period as the grape harvest approaches in about two weeks. After a month without rain, vineyards are showing signs of stress. Growers and experts are closely watching the weather, hoping that the rainfall forecast for the end of this week will help increase grape yields, which are currently estimated to be below 90 hectoliters per hectare. However, there is concern that too much rain could also lead to rot in the grapes.

Pierre Forgeron, an independent viticulture consultant in the Grande Champagne appellation, advises winegrowers to return from vacation soon to prepare their cellars. This week, one of his clients began harvesting 3.5 hectares of folle blanche grapes. According to Forgeron, these grapes were already very ripe during the last check on August 23, with potential alcohol levels between 8.3% and 8.8% and acidity at 7.5 grams per liter of sulfuric acid. The recent heatwave prevented the berries from growing larger but did not slow their ripening process. As a result, some grapes are small but have high sugar content.

On August 18, teams from the Station Viticole of the Bureau National Interprofessionnel du Cognac (BNIC) sampled ugni blanc grapes from 59 representative plots across the region. The average potential alcohol was measured at 7.4% by volume, up by 1.3 points from the previous week, while acidity dropped by 4.8 points to 8.2 grams per liter. Since ugni blanc typically ripens two weeks after folle blanche, Forgeron doubts that harvesting will start as late as September 15, especially since some plots had already reached 10% potential alcohol by August 25. He compares this early vintage to those of 2011, 2003, and 2022.

Laetitia Caillaud from the Charente-Maritime Chamber of Agriculture expects harvesting to begin around September 8, which falls on a Monday this year. She hopes most growers will wait until September 10 or 11 so that the grapes can benefit from the expected rainfall.

Since July 23, most of the Cognac vineyards have not received any significant rain except for a few areas like Chenac-Saint-Seurin-d'Uzet or Rouillac. Caillaud notes that some plots are starting to suffer, especially those that have not been cultivated or are newly planted. Forgeron adds that he has not seen colombard vines die from drought in many years.

Current yield estimates are around 92 hectoliters per hectare according to the Chamber’s network and between 70 and 90 hectoliters per hectare according to BNIC figures. This year, BNIC has lowered the annual yield limit to 7.65 hectoliters of pure alcohol per hectare.

Both Forgeron and Caillaud agree that at least 30 millimeters of rain would be needed to improve yields significantly—though even then, growers do not expect more than a five or six hectoliter increase per hectare. Forgeron believes that rainfall between 30 and 40 millimeters could change the outlook for this year’s vintage but warns it could also bring problems if it causes fragile berries to burst or rot after being weakened by sunburn.

There have already been some reports of botrytis (a type of rot) on folle blanche grapes last week, indicating an increased risk if wet conditions persist. Caillaud has also observed some rot but is less concerned because she says folle blanche is naturally prone to rot and current vineyard health is good overall, with low populations of grape moths.

As Cognac producers wait for rain and monitor their vineyards closely, they face a delicate balance between improving yields and avoiding disease before harvest begins in early September.