By Sonya Logan, Editor of Wine & Viticulture Journal
Vineyards in the Grampians wine region in western Victoria and Coonawarra region in South Australia have suffered up to 100% damage from a black frost which hit in the early hours of Saturday 4 November. There are also reports of frost damage in SA’s Padthaway region.
While the degree to which the frost will impact the forthcoming vintage in those regions is still being assessed, the cost has been significant for some, particularly in the Grampians, where some of the oldest and most prized vineyards of the region have suffered extensive damage.
Best’s lose some of their best
Ben Thomson, managing director and vineyard manager of Best’s in the Grampians’ sub-region of Great Western, admitted he had to take the day off work last Friday after the sight of blackened vines while driving into the winery’s headquarters at Great Western every day got the better of him.
“We didn’t know how much damage we had until last weekend. We really only started to see the extent of the damage four to five days later.”
“We didn’t know how much damage we had until last weekend. We drove around the vineyard the day after but we really only started to see the extent of the damage four to five days later,” Thomson said. “I thought some of our stuff looked alright. I thought our Riesling looked fine – they had about six inches of shoots still left on them so I thought they’d be ok. But, three days later we had 30-degree heat so whatever was left on them dried up pretty quickly.”
Thomson said damage throughout the vineyard, which contains vines up to 150 years old and was about two weeks from flowering, ranged from burnt bunches to burnt shoots and bunches.
“Shoots that were 600mm long had burning down to 200-300mm. Some of those had burnt bunches as well. Others just lost bunches.”
Although four frost fans are installed in the vineyard, Thomson said the inversion layer was too high for them to have any significant effect.
“In some spots they worked. In one spot the temperature was -2C before the fan came on which came up to about -0.5C after it turned on. In those sections the vineyard was not as badly damaged; that’s where we only lost bunches. But the air above [the fans] just wasn’t warm enough to make a difference in other parts.”
Thomson said the damage to the vineyard would hurt their sale of whites around July and August next year when they would normally be releasing those wines to market from the most recent vintage and red sales in the following year.
“The vines are starting to shoot again. We’ve given everything a dose of calcium nitrate. We’ve put some Seasol on as well. Hopefully that will give them a kick. Vines with shoots that are 300-400mm long are reshooting halfway up. Vines that were burnt to the cordon are just showing signs of shooting.
“We’ve debated about whether to knock everything off.”
“We’ve debated about whether to knock everything off. It would be expensive to strip everything off in the hope things burst again. But we’d be into December by the time they started to reshoot which means they wouldn’t get much length on by January when the hot weather hits.
“We are going to shoot thin our Pinot to try to get some more light into basal buds. We would normally shoot thin those anyway but we’ll do it harder this time.”
“Right now I’m more concerned about ensuring we have wood for next year’s pruning season.”
Best’s owns a second vineyard 12km away from its estate block at Great Western. Thomson said this vineyard was 80-90m higher and only suffered “a touch of frost damage on a couple of rows of Pinot and some odd vines here and there.”
“This year was looking really good. The vines looked to be in really good balance. And a lot of shoots had three bunches per shoot with good wings, like our Riesling. We’ve had decent rains too so there was good moisture in the ground. The worst part I think is that it feels like we’ve just wasted the last six months.”
Frost fans offer little help
At nearby Grampians Estate, proprietor Tom Guthrie said he didn’t have a single vine that wasn’t damaged in his 12-acre vineyard in the 4 November frost.
“As an indication of the severity of the frost, our weather station showed a low of -3.1C at 6.00am on Saturday. It had already reached 0C by 1.00-2.00am.
“We have two frost fans – one automatic, one manual. The first one was already on when I turned the manual one on at 4.00am. But, because of the depth of the cold air they didn’t work.
Guthrie said canes in the vineyard were about 30cm long and were looking healthy when the frost hit.
“That would normally give you extra protection being that advanced. But not along after the frost those whole shoots were pointing down to the ground.
“I’ve been in farming and wine for a long time. I haven’t experienced anything like it before. Will there be new shoots that come up? I’m not expecting to get any. And if we do are they going to produce fruit we can use? The new shoot would have to flower in January and I don’t think that’s going to happen.”
The value of the fruit that wouldn’t be picked from the vineyard in 2018 was around $50,000 but the loss in wine value was 10 times that.
Guthrie said the value of the fruit that wouldn’t be picked from the vineyard in 2018 was around $50,000 but the loss was 10 times that in not being able to turn that fruit into wine.
In a statement, Treasury Wine Estate’s said “a small section” of its Great Western vineyards was impacted by the frost event on the 4 November, adding the full extent of the impacts would take some weeks to materialise as the vines were monitored and assessed. The company said given its extensive production network throughout Australia, it was “well placed to minimise the risk from any impacts on a particular vineyard or region by sourcing grapes from other regions”.
Pete Balnaves, president of Coonawarra Grape and Wine Incorporated and viticulturist for Balnaves of Coonawarra, said the random occurrence of damage in his region from the 4 November frost made it difficult to quantify its impact.
“The affect across the region is fairly patchy. The further south you go the less damage there is. The southern end didn’t get as cold as the northern end. But it’s just so patchy.
“Some vineyards are completely fine. Others only got partially burnt. So it’s hard to put a number on it. But there will obviously be some crop loss.
“If it had been two weeks earlier bunches would have been at the top of canopies. So, in that regard, some vineyards have only lost the tips of shoots but still have inflorescenes. But in colder parts of the region the damage has moved past the shoot tip.”
He said previous significant frost events in the region had shown that if vines were burnt below the fruiting line, they would shoot again, but only a percentage of full production would be harvested from those vines.