The clear blue skies and glorious sunshine sure make for a nice photo. But while wine grapes need sunshine to ripen, this year’s heatwave is slowly causing havoc to local vineyards.
Though it isn’t catastrophic according to Pfeiffer Wines owner Chris Pfeiffer, who assessed his fruit crops during a January period that had 12 days where the temperature exceeded 40 degrees.
“What you find when this happens is the vines as a defense mechanism shut down to try and protect themselves and all we can do really is to try and reduce the amount of heat that’s getting into the fruit,” Mr Pfeiffer told The Free Press.
“You do that by hopefully having a significant enough canopy and then manage the canopy to provide shade over the fruit.
“The water level also needs to be kept up, it’s pretty well saturated.
“But it’s been a bit of a struggle because in the middle of the night, and when things cool down a bit, the plant starts taking up water so it can actually cool itself down.
“Normally when you pump a lot of water onto a grape vine it grows huge bunches with huge berries and little flavor.
“The bunches are going through veraison – with reds they’re going from dark pea green to red and with whites they’re going from darker to the golden green colour.
“The berries are still the size of my small finger nail so I think our crops subsequently will be down this year because the berries aren’t as big so there won’t be as much weight.”
Mr Pfeiffer said he has noticed some fruit die in some areas with lack of development, but hasn’t needed to do a significant amount of thinning and says it’s too early to declare crop a complete waste.
“It’s like seeds hanging off the end of a dried up desiccated stalk,” he said.
“The other thing that happens is the sugar can really fire very quickly and in doing so we get very alcoholic wines, and it’s not desirable we prefer to have slower accumulation of sugar so that when we pick them, with good fruit flavor the sugar is not quite as high so the wine will be in better balance.”
Though he has to prepare for each summer knowing that temperatures will rise, it’s not the same issue that Mr Pfeiffer needs to combat in order to consistently produce.
“Last year because it was cooler we had slightly different problems, we probably had more disease problems last year than this year,” he said.
“The big thing about this year is your disease level is reduced which is good, but last year it was cooler and more humidity, our disease risk was a lot higher.
“We haven’t really done some serious testing yet but tasting them in the vineyard they don’t taste right.”
Despite not knowing which problems he’ll be dealing with at this time of the year – albeit conducting the usual process of manipulating foliage to gather extra shade – Mr Pfeiffer said the lack of rainfall has not surprised him.
“I guess we just have to accept what we get. It would be terrific if we could dial up exactly what we wanted to grow perfect grapes to make great wine, but part of the training of a winemaker is to have to deal with what they’ve got, and how you best respond to those conditions to get the best out of it,” he explained.
The crops don’t look as high this year according to the experienced winemaker.
But with the amount of water being applied, “we might actually get bigger crops in 12 months’ time”.
“That’s why you have to prune them in such a way. We have to be thinking about 2020 as well as to what’s in our vines,” Mr Pfeiffer said.