05.05.2015  
 

The Winter That Just Wouldn't Quit

Second consecutive frigid winter proves tough on grapevines producing eastern wine

 
by Linda Jones McKee
 
“cold
 
Viticulture extension specialist Hans Walter Peterson from the Finger Lakes Grape Program at Cornell University surveys grapevine buds to see if they survived frigid winter temperatures in this video still. He says that snow helped insulate many vines against trunk damage.
Lancaster, Pa.—Grapegrowers across the East and Midwest hoped the winter of 2014-15 wouldn’t be as severe as the previous winter, when the infamous Polar Vortex delivered extremely cold temperatures multiple times from December through March. This past winter began with milder weather, but in mid-February temperatures dropped below zero from Virginia to New England and across the Midwest. And once it turned cold, it stayed cold.

The good news for growers in many regions was that the vines were ready for cold temperatures. Tony Wolf, professor of viticulture at Virginia Polytechnic Institute & State University, stated in his Viticulture Notes supplement in mid-March that “vines were probably at or near their maximal expression of cold hardiness given the preceding cold, but generally non-injurious, temperatures to which they had been subjected. Had the extreme cold been preceded by unusually warm temperatures (>50° F), the vines would likely have fared worse.”

In some areas, other factors came into play. In Michigan, for example, the stressed condition of vines as a result of the previous winter’s frigid weather may have made them more susceptible to damage from another cold winter. According to Paolo Sabbatini, associate professor of horticulture at Michigan State University, Michigan historically has had a really difficult winter every 15 to 20 years, and to have two cold winters in a row is very tough on grapevines.

The presence or lack of snow in vineyards can also play an important role in ultimate vine health. Sabbatini told Wines & Vines, “In 2014 we had snow up to the cordons, but this year we had limited snowfall. We had three events when temperatures dropped below the limit for grapes, and I think we may see lots of damage. But we’ll have to wait for spring to determine how much trunk damage there is.” In Sabbatini’s estimation, bud break probably won’t occur for another two weeks. Sabbatini thinks there may be a 100% loss of the Merlot, Traminette and Cayuga crop, but that Riesling may be in “pretty good” shape. Marquette, the premium cold-hardy grape for red wine, and other Minnesota hybrids don’t seem to have much damage.

In the upper Midwest, the Great Lakes have a major impact on weather conditions. This winter Lake Michigan froze solid and Lake Erie was 95% frozen for the second straight year. Those two large bodies of water help to moderate the cold winter temperatures for vineyards planted relatively close to them in Michigan, Ohio, Pennsylvania and New York, but when the lakes are covered with ice, that moderating influence disappears. Sabbatini anticipates that the water temperature in the lakes may be lower because of two years with ice cover, and the result may be a cooler summer, which would make it more difficult to ripen grapes, especially if the crop is a large one.

Mario Mazza, enologist and vineyard manager for Mazza Wines in North East, Pa. (which is located northeast of Erie, Pa. not far from Lake Erie), also commented on the influence of the ice on Lake Erie. “Bud break is late when the lake has been frozen,” Mazza noted. “The ice really slows things down. But that also means a lower risk for frost damage.” He reported that the Lake Erie grape belt that stretches from Ohio through Pennsylvania into New York will certainly have some winter damage. The low temperature in North East dropped to -19° F, and temperatures were as low as -26° F to -28° F in other parts of the region.

The Penn State Lake Erie Regional Grape Research and Extension Center reported a low temperature of -21° F on Feb. 16, according to Michela Centinari, assistant professor of viticulture at Penn State University. She reported, “On a positive note, the week before these extreme cold events, temperatures were lower than normal, with daytime temperature highs well below freezing, except for one day (34° F). These temperatures may have provided a positive, reinforcing maintenance of the vines’ mid-winter cold hardiness.”

New York
The winter of 2014-15 was the Finger Lakes region’s turn for snow cover in the vineyards. Hans Walter-Peterson, viticultural extension specialist with the Finger Lakes Grape Program at Cornell University, reported that there was 2 to 3 feet of snow in the vineyards in February. Growers had to wait to get into the vineyards to prune, but the snow served to insulate the grapevine trunks from temperatures that dropped as low as -15° F. As in other parts of the East, when it got cold, the weather stayed cold. According to Walter-Peterson, even though it was colder than normal, “We had some of the best winter hardiness numbers we’ve ever seen.”

He told Wines & Vines that he is now trying to get a sense of what has and hasn’t happened in the vineyards this winter. “The hybrids and natives look pretty good,” he reported, “but we’re just getting into bud break. It’s an incomplete story until we get to June and July and can assess trunk damage.”

Virginia
Temperatures in Virginia went below zero on Feb. 19, 20 and 23, with many vineyards in the -2° F to -6° F range. As with many other eastern wine regions, temperatures continued to be cold. As Wolf put it, “Spring seemed to take its sweet time getting here to Virginia this year.” Tremain Hatch, viticulture research associate at Virginia Tech, confirmed that the weather in March and April continued to be cool. On the other hand, he commented, “We hope we’ve dodged the bullet for spring frosts. We’re just getting bud break, and things have been good up to this point. Overall, we’re running about a week late compared with the long-term average.”

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