Frost has left vines 'looking like dried tobacco' recently in wine regions across Europe. But how can winemakers help to prevent frost?

prevent frost

Fires to prevent the frost at Ridgeview in Sussex. Credit: Julia Clatxon: International Garden Photographer of the Year/Royal Photographic Society Silver Medallist

Frost protection – Switzerland

Frost protection with fire buckets in the vineyards of Switzerland tonight.Meteo Europe Severe Weather Europe WetterOnline

Posted by Marco Kaschuba on Friday, April 21, 2017

Above: Fires prevent frost in Switzerland in April 2017. Credit: Marco Kaschuda.

Frost is a particuarly big risk for cool climate wine regions, where it can severely damage the newly emerging buds.

In Champagne, losses of 20% in some areas and up to 50% in others have been reported by vineyard managers recently.  It also is a frequent problem in areas like Chablis, the Loire and also the UK. But the past week has seen hundreds of hectares damaged much further south, too, in places like Languedoc-Roussillon on the Mediterranean coast.

Here’s some techniques and action-shots of how winemakers seek to limit frost damage on their vines.

Fire

At Ridgeview in Sussex they use ‘bougies’ – large paraffin candles which give off enough heat to create air movement which prevents a frost pocket forming.

Burning bougies at Ridgeview in Sussex. Credit: Julia Claxton: International Garden Photographer of the Year/Royal Photographic Society Silver Medallist

‘Our vineyard team stay up overnight, constantly checking the weather stations for sign of a frost and when the temperature does drop, they must quickly head out to the vineyard to light the bougies,’ said Hannah Simpson-Banks, Retail and event manager at Ridgeview.

Frost preventing fires at Ridgeview in Sussex. Credit: Julia Claxton: International Garden Photographer of the Year/Royal Photographic Society Silver Medallist.

‘It takes our team around 50 minutes to light them all,’ said Simpson-Banks.

Ian Kellett, from Hambledon Vineyard, in Hampshire, said his team used vineyard stems from pruning as fuel source for fires, which are lit in bins.

Fans

A wind machine waits to defend against frost in Calistoga, Napa Valley. Credit: George Oze / Alamy Stock Photo.

Using fans and wind machines to keep the air moving also helps to prevent frost.

‘We are trying to move air as much as warm up the local immediate environment. We have big fans running through the night to to try to move the air,’ said Kellett.

Helicopters

Two helicopters fly above vines, effectively whirling cold and warm air in order to raise the temperature in the vineyard and preventing late frost on a vineyard in Obersulm, Germany. Credit: Christoph Schmidt/dpa/Alamy Live News

Helicopters are also used for air displacement to help prevent frost, although this is not quite as common.

Several winemakers used them in Europe last week, including in Baden-Württemberg in Germany and also in France’s Loire Valley.

Sprinklers

Other common methods include using heaters in the vineyard, to keep the air too warm to allow frost to settle, or using sprinklers – which help to keep the temperature above freezing.

Frost will rarely affect a vineyard region equally, and the risk is a consideration when choosing a site.

Factors for winemakers to consider in the vineyard include choice of site and variety, and trellises, which can mitigate frost to an extent.

(http://www.decanter.com/learn/winemakers-prevent-frost-ask-decanter-367606/)