Grape growers on frost watch

The frost-fighting season has begun for grape growers in Central Otago.

New Zealand Wine chairman and Carrick Wines owner Steve Green said Monday night was the first ''major'' event of the frost-fighting season for grape growers throughout the region.

Grasshopper Rock vineyard manager Mike Moffitt said temperatures at the Earnscleugh property dropped to between -2degC and -3degC on Monday night.

However, vines ''came through it fine''. Eight Ranges co-owner and vineyard manager Trevor Deaker said Monday was the third night of frost-fighting for the vineyard, at the east end of the Alexandra Airport.

Temperatures dropped to about -1.4degC at 6am yesterday morning at his vineyard after hovering around zero most of the night, he said. Frost-fighting systems at the vineyard were turned on about 12.30am.

Mr Moffitt said vineyards in the Alexandra Basin were usually on frost alert from early October, when vines became vulnerable to frost damage during and just before bud burst.

Sprinklers were the method of choice used at Grasshopper Rock, as wind machines were not reliable enough in the Alexandra Basin.

Sprinklers sprayed water on to the vines and the chemical reaction which formed ice released latent heat, protecting green tissue from frost damage.

Felton Road Wines viticulturist Gareth King said it was ''early days'' for the Bannockburn vineyard.

''It's really just getting started for the vines; fruit growers have been going for a while.''

Gibbston Valley's Coal Pit Vineyard viticulturist Gary Crabbe said Monday night was the first serious frost for that area as well.

The valley had a frost-fighting season which usually ran from mid-October until late November, during which he had ''a few sleepless nights'', as frosts could ''burn'' new flowers and leaves..

''If you burn your flowers you have lost your crop,'' Mr Crabbe said.

Unlike the Alexandra Basin, which mainly used sprinklers, most of Gibbston valley used frost fans.

Frost fans, or wind machines, force an air stream down into cool air around vines, causing it to circulate, preventing the temperature from getting too cold.

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