Cold snap takes toll on vines

Marlborough's grape growers may have had their fingers burnt by last week's frost, which saw record equalling low temperatures scorch vulnerable vines near Blenheim and Renwick.

Some growers will be holding their breath to see how the damage affects their yield, while others are saying the damage is minimal.

The frost has been compared to a one in 10 year frost, and Blenheim Airport recorded -3 degrees overnight on Thursday.

That equalled the lowest temperature recorded during October, and such low temperatures may have limited the effectiveness of the frost fighting capabilities of the wind machines and 100-strong swarm of helicopters that took to the air.

Last year spring frosts and a cool December contributed to a 15 percent reduced yield at harvest, but vineyard expansion still meant an increase in Marlborough's production, worth millions of dollars to the region.

New Zealand Wine Growers chairman Stuart Smith said it was pretty hard to estimate the overall damage at this stage.

He said chardonnay and pinot grapes had been hit, but it was nothing like the late frost of November 2002.

The Marlborough Focus Vineyard Project is coincidentally holding a seminar on frost protection tomorrow, where growers will have a chance to compare notes.

Climate Consulting climatologist Stu Powell said there was plenty of damage around, but it appeared to be concentrated around Fairhall, Rapaura, Kaituna and the North Bank.

Around the Wairau Valley township it hit -2.7 degrees, but further south, in Awatere and Ward it was warmer.

Mr Powell said that some areas towards the coast, which did not normally get damaged, also suffered from the frost.

It was probably too early to say how much of the crop had been damaged, he said.

Wither Hills viticultural operations manager Geoff Matthews said the damage was "a bit depressing".

The early varieties of chardonnay and pinot noir suffered primarily, but there was damage to sauvignon blanc grapes too.

He was yet to have a proper look around, but the damage appeared to be worst around the Southern Valleys area and Middle Renwick Rd south.

The damage was on the fringes of the areas protected by helicopters and wind machines. "I think the duration of it also has something to do with it. It's more the fact the frost conditions went for a six or seven hour period."

As the night wore on, wind machines and helicopters were less able to raise the temperatures.

He thought it might have been a one in 10 year frost. "It has the potential to drop the yield, but really it's just a case of waiting and seeing what happens. This is no worse than the poor flowering the sauvignon blanc had last year."

Peter Clark, manager of Delta Vineyards, said the 27ha block of pinot suffered "very sporadic type damage". Some areas were unaffected, while others could have suffered 50 to 70 percent damage.

However, he estimated that perhaps just under one hectare had been lost.

Dog Point Vineyards viticulturist Nigel Sowman said the vineyard had suffered about 20 percent losses in a chardonnay block, despite it being protected by a helicopter, and "a little bit of a touch up" in other parts of the vineyard.

Fromm Winery winemaker Hatsch Kalberer said some of the vineyards up around the Brancott Valley initially looked to have suffered five to 10 percent damage, but that was before shoot thinning, which meant the damage could be minimised.

"I think we can count ourselves lucky. I don't think we should be complaining."

It meant getting off lightly from what was a very hard frost.

Last Thursday night saw an armada of helicopters trying to help wind machines and frost pots ward off the cold, but it was so cold they could have lost their effectiveness as the night wore on.

- The Marlborough Express