Weathering winter: New vineyard management practices
Agriculture and Agri-Food Canada
Canadian winters can be tough on wine grape vines. A single extreme cold snap can damage vines and reduce crop yields by 50%.
Agriculture and Agri-Food Canada researchers in Summerland, British Columbia, are collecting data from multiple sources to determine the best practices for protecting vineyards against extreme cold.
"It's really important to understand how we can help vines weather cold snaps that occur periodically, and to develop new vineyard management practices that can improve the cold hardiness of the grape vines."- Carl Bogdanoff, Biologist, Agriculture and Agri-Food Canada
When winter temperatures drop below −20° Celcius for an extended period, the entire crop is at risk. Vines can be severely damaged or killed outright, amounting to a significant financial loss for growers and vintners. Finding ways to make vines hardier and able to withstand even one or two degrees of lower temperature can prevent winter damage and reduce crop loss and the need to replant.
Carl Bogdanoff and his team at the Summerland Research and Development Centre are working with grape growers to better protect vines against the deep freeze. The research is a multi-disciplined initiative with industry fully engaged as a key partner. The team monitors temperatures and bud hardiness at many locations across the Okanagan and Similkameen valleys, in part to determine if vineyard management practices influence hardiness.
The wine industry has evolved significantly in British Columbia since the 1980s, when it was fairly small and based on winter-hardy hybrid varieties. In 1990, there were only 17 wineries in British Columbia but that number has since grown to over 250.
In the 1990s, vintners replanted all their vineyards with premium Vitis vinifera varieties, such as Merlot, Cabernet Franc and Chardonnay, to take advantage of a growing domestic market and emerging trade opportunities. While these vines can tolerate some freezing, they are severely tested when temperatures approach record lows between November and March.
Too much cold kills grape buds and can damage the vine's tissue and roots. If the damage is serious enough, it will kill the vine outright. In some cases, a vine will produce buds normally but will collapse and die after becoming stressed later in the season.
All growers have access to a bi-weekly bud hardiness report for major wine grape varieties. They use this information to assess risk of winter injury before and during an arctic outflow event (any combination of wind speed and temperature giving a wind chill of −20° Celcius or lower for six hours or more) to help them decide, for example, when to operate fans that draw warmer air into vineyards. Knowing bud damage levels also helps growers decide how much to prune.
Additionally, the research team collects hardiness data in several other current research projects that are looking at the effects of irrigation practices, crop load adjustments, ground cover between vine rows, trunk and viral diseases, leaf removal and cluster positioning, and applications of abscisic acid (a natural plant hormone that improves grape colour) on fruit and wine quality.
- Making vines hardier by even one or two degrees can prevent winter damage and reduce crop loss and the need to replant.
- Each summer, the team's interim results are presented at the BC Wine Grape Council's Enology and Viticulture Conference. Final results will be made available to growers in 2019.
- Over 30,000 acres of wine grapes were cultivated in Canada in 2014, generating over $111 million at the farm gate.
- Over Wintering Strategies: New vineyard management practices (video)
- Summerland Research and Development Centre
- British Columbia Wine Grape Council
- Canadian Vintners Association
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