Mark Chien speaks about his experiences:
I never imagined that the big viticulture story for me in 2011 would be plastic. My father was a polymer chemist so maybe this was inevitable. As I wander around the country and even in my backyard, I am seeing plastic at work in creative ways in vineyards.
I think the story begins with wine growing being done in places that have been traditionally inhospitable for vine culture, not just vinifera, but any species of vine. As new technologies, such as cold hardy hybrids, push the limits to further extremes of environmental conditions, of course the stubborn and innovative grower asks, “well why not vinifera (or whatever)?” Where plastic appears means that viticulture is being practiced on the climate margins and the practitioners are probably pushing their varieties too hard, which seems to be the nature of wine growing. The question is how far can technology push the limits of fruit maturity?
To catalog my experience this year I encountered the rather large scale use of Haygrove high tunnels on the Old Mission Peninsula in northwest Michigan where four acres of Merlot and Cabernet Franc are under plastic. Then, in the Wine Islands of British Columbia I was introduced to plastic tents that cover individual vines. Right here in Lancaster there are two Haygrove trials, the most significant is 1/8th acre (4 rows) of Cabernet Sauvignon and Petit Verdot. In his recent lecture Daniel Roberts explained how growers in the cool Sonoma Coast district are covering the fruit zone with plastic to trap heat to improve fruit set. Also, on the North Fork of Long Island, Bedell Vineyards has used black plastic to cover the vineyard floor on its reserve Cabernet Sauvignon to divert late season rainwater from the vines.
There is a lot of environmental manipulation going on here and that, too, is no surprise, perhaps an inevitable form of viticulture management cool wine regions. Instead of going where it’s warm, growers are trying to bring warmth to where it isn’t. John Gladstones and every manner of viticulture researcher has explained how important temperature is to all functions of vine and berry so we know it is the key to unlocking wine quality. The uncharted territory was how the environment could be artificially altered to improve fruit ripening conditions. There have been experiments with reflective ground covers but those have only had some success. We can lower the fruit wire to pick up heat from the ground. But maybe it was only a matter of time before the vineyard was placed under a bubble. With the tunnel there could be viticultural benefits at the front and back ends of the growing season.
Here are the possible pluses and minuses that I can think of for tunnel winegrowing:
- Greater consistency achieving mature fruit
- Earlier budbreak and fruit ripens sooner than uncovered grapes
- Control of vine-water relations, ability to use regulated deficit irrigation
- Finer control of nutrition using fertigation
- Less disease problems Possibly less insect problems
- Longer and better acclimation period resulting in enhanced cold hardiness
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