Après le déluge: Bordeaux’s winemakers fight back

French winemakers have declared war on the weather. Even before the storms that dropped hailstones as big as tennis balls on the Bordeaux vineyards last weekend, one month before the wine harvest begins, producers had lined up an arsenal of gadgets to protect their precious grapes from bad weather.

Some methods have been tried and tested over time; some have been abandoned as ineffective; others have tried to harness new technology to the age-old industry.The 15-minute hailstorm that swept across the vineyards of Bordeaux last Friday destroyed 5 per cent of the vines in the area. The region of Entre deux Mers, which produces dry white wines, was particularly badly hit. At least 7,000 of Bordeaux’s 115,000 hectares were devastated. Wine crops have also been destroyed in the Burgundy and Beaujolais regions.

The storms have brought fresh attention to the counter-measures available to winemakers, who say none of them are perfect. Julie Mounet-Brun represents 450 vintners producing Blaye Côtes de Bordeaux wines. She says that in her area, cannons are used to fire silver iodide into the atmosphere. The iodide dissolves the hailstones, which then turn into rain.

“The trouble is that there aren’t enough of them to be effective,” she says. “The storms we get come from the Landes region, so the cannons need to be positioned correctly. And we need enough warning.”

There are also vortex generators, but they need to be switched on three hours before the estimated arrival of the hailstones. And they must be installed every 10 kilometres over a large area to be effective.

Some growers used an anti-hailstone rocket that was developed in the 1970s. It was fired into the atmosphere, where the sodium iodide it contained was supposed to dissolve the hailstones. But producers gave up on the method in the 1990s as it proved ineffective, dangerous and costly. Michel Dubois, a retired winemaker in the Loire region, said that another option was to erect nets over the vines which would catch the hailstones before they caused damage. “But that didn’t work. Sometime the hailstones would be so heavy that they broke down the nets.” He also said it was impossible to work in the vines because of the netting.

For Mr Dubois there is only one foolproof method against hailstones: insurance. But 70 per cent of growers do not take out insurance in the hope that they will not be affected by a freak hailstorm.

Christophe Vaudoisey, a winemaker from the Côte d’Or region of Burgundy, told France2 television this week that he could no longer afford not to take out insurance. Hailstorms used to hit every 20 years, “but now they’ve [struck] six times in the past 12 years,” he said. Each time, between 60 and 90 per cent of the wine harvest has been destroyed.

Vintners dread hailstorms but they are just as afraid of frost, which can decimate a crop – particularly if it comes in late spring, when the buds are bursting. Spraying vines with water is a popular way to keep their temperatures above freezing. Wind turbines are also used across the vineyards to protect against frost. The giant turbines mix slightly warmer air with the cold air lower down, raising the temperature at vine level by a couple of degrees.

Traditional fuel heaters and paraffin torches remain widespread. The heaters switch on and off automatically in response to the temperature. But they have been criticised for damaging the environment, so some wineries have substituted gas as the heater fuel.

Mrs Mounet-Brun said some grape producers used to burn tyres among their vines, giving off acrid smoke.