situation from anywhere in the world,” he explains. The winery has more a $1 million invested in wind machines, not to mention the cost of operating them, but that investment has all been paid back in reduced losses to winter damage.
Vineyards are a huge investment in the vines alone, not to mention in their production every year, so being able to reduce the amount of damage to production every year can add up to dollars that are significant no matter what size your operation is. “That damage affects your potential for productivity. Even if it’s only 10 or 15 per cent year after year, it mounts up,” notes Molloy. Grape growers in areas such as Ontario and Washington State began using wind machines to counteract winter damage to grapes quite some time before B.C. growers did. Winemaker John Simes drove the issue at Mission Hill because he recognized the cost of lost productivity that could be caused by recurring winter damage. They began with seven Orchard Rite wind machines installed in the
south of the valley in August of 2000, then five more in November that year.
Today Mission Hill runs 40 wind machines to prevent incremental winter damage.
It used to be that wind machines were used to protect soft fruits in the Okanagan Valley from frost damage in late fall, before dormancy, and in early spring, once the trees had begun to come out of dormancy. However, today it’s realized that winter damage to grapes can also be prevented by protecting vines from a critical few degrees of cold, even when they’re dormant.
“If you have good air drainage in the vineyard and it’s located close to a big lake like Okanagan, you don’t need a wind machine, particularly if you’re growing hardier varieties like Riesling,” commented Molloy, as he stood in a steeply-sloped vineyard of Riesling grapes near Mission Hill winery, overlooking Okanagan Lake. And, there are other factors: if the vines are stressed going into winter, they’re more susceptible to winter damage. Watering them too much just prior to them going into
dormancy can cause that sort of stress, for instance. Molloy has photos showing dramatic examples of winter damage caused in vineyards where the vines were just outside the influence of a wind machine, while those closer in are thriving.
The vines throw out more suckers from lower down when there’s vascular damage higher up the vine from cold winter weather. Scientists Carl Bogdanoff and Pat Bowen at the Pacific Agri-food Research Centre in Summerland have been doing research on factors that influence cold hardiness in grapes, variety susceptibility and locations throughout the region that are more prone to extreme cold. Bogdanoff is a biologist doing viticultural research into wine grapes and says there are many factors, including the health and age of the vines, cultural practices such as cropping levels, and frost protection such as wind machines or sprinklers. “Wind machines work when there’s no wind. We looked at extreme weather and when the wind stops and the temperature drops
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British Columbia FRUIT GROWER • Spring 2011
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