Life in the Midwest and Northeast came to a halt when a polar vortex brought record low temperatures this week. Here is a roundup of stories from local news media concerning the impact of cold temperatures on winegrapes.
Winegrape growers in the Finger Lakes were concerned that temperatures would dip low enough during the early part of this week to freeze the moisture in the trunks of the vine, cracking the vines open. Fred Merwath, head winemaker and vineyard management at Hermann J. Wiemer Vinery in Dundee, NY, told wine-searcher.com that researchers from Cornell University determined heavy damage to Riesling would occur if temperatures dipped below –12°F.
Peter Martini, vineyard manager of Anthony Road Winery in Penn Yan, NY, told wine-searcher.com that this cold snap will mean a smaller 2014 crop. “Things like Gewürztraminer and Merlot, we’ll probably lose 50 or 60%. Riesling might be better off, and maybe Cabernet Franc.”
Merwath says that regardless, site selection is still a key component of whether a vineyard can withstand extreme cold in the winter, telling wine-searcher.com that “the best vineyard sites will prove themselves year-in, year-out.”
Lee Hartman, manager and winemaker of Bluestone Vineyard in Bridgewater, VA, told WHSV-TV3 of Harrisonburg, VA, that he was worried about what impact the cold snap would have on his grapes.
“Two years ago, we had two days in a row of negative 10 degree weather, and we lost a couple thousand vines. It would be a very significant impact. If you don’t have vines, you don’t have grapes. If you don’t have grapes, you don’t have wine,” Hartman told WHSV-TV3. “We had a late frost this past year. We were still able to get a little more than half of our original anticipated harvest, but it really hurts a lot.”
Colio Estate Wines in Harrow, Ontario, Canada had to stop the harvest of Vidal grapes for ice wine thanks to temperatures reaching -17°C, according to the Windsor Star.
Winemaker Lawrence Buhler told the Windsor Star that wind machines would be deployed to try and prevent the vines from freezing. Buhler did say that cold temperatures are far better in the winter than in the fall or spring. “In January usually (the vines are) already ready for that cold weather and some fingers crossed, we come through unscathed.”
Northeast Ohio grape growers are expecting a large loss to the 2014 crop, Doniella Winchell, executive director of the Ohio Wine Producers Association told the Willoughby News-Herald.
“It’s at least a $3 million loss of vinifera grapes. More than 90% of the buds among the Chardonnays, Pinot Noirs, and Pinot Gris were killed,” Winchell tells the News-Herald.
Wind machines proved useless with wind gusts of 25 mph, Tony Debevec of Debonne Vineyards in Madison, OH, told the News-Herald.
“When we get frigid weather on a still night, we can use the machines to invert the warm air in the inversion layer and raise temperatures 5 to 7 degrees. But this wind thoroughly mixed it up and made it impossible to do anything,” Debevec told the News-Herald. “I‘ve been in this business for 50 years and know it’s cyclical. Everyone in this region will see a big loss this year. We just have to hope that the vines haven’t been destroyed.”
Lee Klingshirn of Klingshirn Winery Inc., in Avon Lake, OH, is slightly more optimistic that his vines of Concord and Niagara will be OK. Damage is likely to his Riesling, Cabernet, and Pinot Grigio grapes. Klingshirn told the News-Herald that it is too early, “at this point you really cannot tell if and or how much damage may have occurred until things start to warm up a little bit.”
Peaches are also a concern for Tod and Ame West of West Orchards in Perry, OH, who lost trees in a 1994 deep freeze. “We saw -11°F early Tuesday. But we won’t know until May if our peach trees survived,” Ame West told the News-Herald.
Winegrape growers in Minnesota hoped that cold-hardy varieties such as Frontenac, Fontenac Gris, Marquette, and La Crescent would withstand the cold temperatures, according to the Minneapolis StarTribune.
University of Minnesota enology project manager Katie Cook told the StarTribune that the vines should withstand -25°F temperatures and La Cresent has withstood temperatures of -30°F.
Jim Luby tells the StarTribune that winegrape vines are the most dormant and hardy in January. The growers who took good care of the vines have may have avoided problems, but the vines probably experienced some stress.
“Some growers may already have some damage from cold in December after a mild November. This is only the first week of January. Even if vines make it through this week, we have a lot of winter yet to come,” Luby tells the StarTribune.
Peter Helmstad, research viticulturist at the University of Minnesota, tells the StarTribune that he worries that growers were “lulled by the recent mild winters,” and planted vines in less than desirable places. Helmstad does think that this cold snap could “increase the level of interest in our cold-hardy grapes.”
Bruce Bordelon, professor and Extension specialist of viticulture and small fruit, and Peter Hirst, professor in the department of horticulture and landscape architecture, of Purdue University sent out a bulletin to subscribers of the university’s Facts for Fancy Fruit eNewsletter discussing the potential damage from the cold snap. Temperatures in the region have been as low as -15°F.
“I don’t think we will know the full extent of damage until the winter is over and we can evaluate damage to the various crops. That is relatively easy to do in grapes but more difficult in other crops. It doesn’t make much sense to do an exhaustive survey of damage now because we still have 6 or more weeks of potentially damaging temperatures to go,” said Bordelon. “We normally do our evaluations on grapes in early March in preparation for pruning.”
Hirst and Bordelon’s observations include:
- “Apples and pears are very hardy but we’re close to the temperatures where we could start to see some bud damage. It seems unlikely that bud damage will be severe enough to reduce crops.
- Peaches and nectarines: The rule of thumb we learned from Dick Hayden is that you start to see some flower bud kill at –10 F and for every degree below –10 F you lose 10% of your flower buds. At –20F expect complete flower bud mortality. Given that the temperature here right now is –13°F (and assuming this is as bad as it gets), we expect to have some early thinning occurring but crop reduction shouldn’t be too severe.
- Sweet and tart cherries: Tart cherries are a little more hardy than sweets, but we could see a little bud damage to both sweets and tarts, but at current temps this is unlikely to limit 2014 crops.
- Blueberries: Highbush blueberries are generally tolerant of temperatures down to –15°F, but the extended period of cold will likely lead to some flower bud kill.
- Blackberries: Thorny and thornless blackberries are not hardy below –10°F so we would expect to see considerable damage to vascular tissue in canes and potentially buds themselves. In severe cases we would expect all above ground growth to be killed. Blackberries commonly exhibit a delayed winter injury response where the buds may have survived the winter cold and begin to grow in the spring, but the damage to the vascular tissue in the canes results in collapse of the new growth a few days or weeks after the start of growth.
- Raspberries: Red and black raspberries are fairly cold hardy and we would expect minimal damage to varieties that are adapted to the Midwest. Some red raspberry varieties from the Pacific Northwest are not very cold hardy and may have been damaged.
- Grapes: Varieties will vary widely in amount of damage. Grapes have a compound bud, with primary, secondary and tertiary growing points. The primaries are usually the first to show cold damage. We would expect hardy hybrid and American varieties to have 0-25% primary bud damage at the temperatures we experienced. That is manageable as we can adjust pruning severity to account for those losses. Less hardy hybrids may have 50% or more bud damage, which could lead to some yield reduction and potentially cane and cordon damage. Cold tender vinifera varieties likely have experienced considerable damage to buds, canes, and cordons and possible damage to trunks above the snow line.”
“Because there are so many factors that influence the amount of damage that will result from a cold snap, it’s very difficult to predict accurately. The recent ‘polar vortex’ resulted in an extended duration of very cold temperatures, so we may well see more damage than the minimum temperatures would suggest,” said Hirst. “Crops of many fruit types was very heavy in 2013 due to severe spring freeze damage the previous year. Normally we expect heavy cropping to predispose buds to increased damage. Despite heavy apple crops, we have seen a high degree of flower formation in buds for the 2014 crop, so if we did see some “early thinning” of buds, this might not be such a bad thing.”