Cover Story Wind warning welcome
When temperatures plunge, it’s time for the bigmachines to fan the frost away. By Judie Steeves
Y
anked from a deep sleep by the sudden alarm, Mike Molloy rolls out of bed, and bleary-eyed, makes sure the warning is passed on to individual vineyard managers. The temperature in certain sites has plunged to within a few degrees of what will be critical to the continued health of buds and even vines there. Earlier winds have dropped off and the air is calm now, which means the temperature could continue dropping like a stone as the coldest air drains off higher terrain and settles in the low spots.
If there are vines planted there, that’s where the wind machines have been located.
Once Mission Hill Family Estate’s vineyard managers arrive at their vineyards and start up the machines, the big blades will begin to move the air, reducing its stratification and bringing higher air that’s three to four degrees warmer down to ground level. A few degrees can mean the difference between the life and death of a bud waiting for spring’s warmer temperatures and longer days of sunshine to begin to swell. It can even mean the difference
JUDIE STEEVES
Mike Molloy, manager of vineyard operations for West Kelowna’s Mission Hill Family Estate, explains how wind machines have proven their value in preventing cold-weather damage.
between damage to the phloem and xylem inside stems— damage that might not be noticed immediately in spring. Instead, later in the year, it will become apparent as some shoots or entire parts of the grapevine fail to thrive, when water and nutrients are blocked by that cold damage in parts of the vine’s vascular system. Molloy is manager of vineyard operations for Mission Hill and says alarm thresholds are based on information from viticulturists and using current information on bud hardiness from a University of Washington website. (
http://www.wine.wsu.edu/research-extension/weather/ cold-hardiness/)
The wind machines are started up prior to air temperatures at the site reaching the critical point, in order to prevent damage in the vineyard from cold winter weather.
Where the critical point is depends on the site and influences such as large bodies of water, the point in the season, recent temperatures (thus the depth of dormancy the vine has reached), and the variety of grape, since some are less cold-hardy than others.
Success of the system depends on their own weather stations in the vineyards and the Adcon wireless weather network, which provides real-time data every 15 minutes on conditions at those sites in the vineyards, day and night, so damage can be prevented.
When temperatures reach the alarm threshold it sends a message to Mission Hill’s network server in Oliver, which in turn sends a message out to key people like Molloy.
“I can get a call-out at any time of year. It’s deadly serious. With my laptop and cell phone I can manage the
British Columbia FRUIT GROWER • Spring 2011 7
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