Northeast And Midwest Grapevine Winter Injury Report
April 9, 2015 
The snow cover on these Vinifera vines is less than 1 foot deep, so very few buds are protected from the cold.
Photo: Duke Elsner
Temperature s dipped quite low in February across the Northeast and Midwest, marking the second year in a row grape growers in these regions have had to deal with potential vine injury and bud loss.
However, it’s not as bad as it could have been, according to experts. Here’s a look at how vines fared in Northeast and Midwest grape-growing regions.
New York
Temperatures in New York dropped down to about -15° F, according to Cornell University Viticulture Extension Specialist Hans Walter-Peterson, but thanks to a couple of factors, vine injury wasn’t as significant as it could have been.
“First of all, when it got cold, it stayed cold, and that actually helped the vines maintain their hardiness better,” Walter-Peterson explains. “The numbers we’re seeing from our tests for bud hardiness were the best I’ve ever seen in many cases.”
That’s good news considering the cold temperatures growers faced could potentially cause 50% bud loss.
“The other thing we benefited from was having 2 ½ feet of snow on the ground to insulate the trunks,” he adds.
That’s not to say there won’t be damage, though, particularly in more sensitive grapes, such as Merlot. Walter-Peterson says some growers have reported higher levels of bud loss in these less hardy varieties, which is to be expected.
There’s also a chance some vines could collapse this year due to last year’s extreme cold.
“If a vine had enough trunk injury, sometimes it’s not the very first year after the cold hits that can take the vine down,” says Walter-Peterson. “Sometimes it’s the following year.”
Michigan
In the Grand Traverse growing region in Michigan, some sites saw multiple days with temperatures of -20° F. These temperatures took their toll on vinifera varieties, according to Duke Elsner, Michigan State University small fruit educator.
“If one just looks at bud condition, the percentage of kill might not be as bad as it was in 2014. However, there was significant injury to the cambium and phoem of canes in the first few inches over the snow cover line,” says Elsner. “Buds that look good above this point may not be able to produce viable shoots.”
Grüner Veltliner was the hardest hit variety, Elsner says, adding that he still needs to examine some of the Muscat cultivars, which were hit hard in 2014.
“Other than that, [it’s] a mixed bag on the vinifera — mostly 20% to 30% primary bud survival at best,” he says.
Hybrids fared much better in terms of canes higher up in the canopy, but cold injury to trunks down near the snow line has yet to be determined, Elsner notes.
The snow cover did help, although it was not as deep this year as it was in 2014.
“It was still sufficient to keep the basal portions of the vines alive and ready to fight back,” says Elsner. “[It’s] another rebuilding year ahead, keeping a lot of shoots from low on the vine to distribute vine vigor, avoid bull canes and provide good cane wood to work with in 2016.”
Ohio
In Northeast Ohio, temperatures dropped below -30° F in February, with most vineyards experiencing temperatures of at least -20° F, according to Imed Dami, associate professor and extension viticulturist at the Ohio Agricultural Research and Development Center in Wooster, OH.
“Since trunks were damaged and already removed from the 2014 polar vortex, all recovering vinifera varieties have canes for trunk renewal this year,” says Dami. “Due to temperatures in the -20s, those canes will be damaged all the way down to the snow line or mound around the graft union.”
Vinifera vines dying back again means more work for growers, who will have to renew trunks by retraining new canes from under the snow mound, Dami adds. He also anticipates crop loss from these varieties, as well as hardier varieties, such as juice grapes and some French hybrids, including Vidal and Chambourcin.
“It looks like we will have another devastating year in terms of damage and crop loss,” he says. “We need a break from these consecutive damaging winters.”
On the bright side, Dami says vines this year are much cold hardier than in 2014, which means less-severe bud damage.
“Also, most growers in Ohio did a good job of protecting the graft union using better equipment,” he notes.
Snow cover, which was absent last year, helped, too.
“It is important to asses bud damage before pruning,” Dami adds. “I always remind our growers that percent of bud damage does not equate to percent of crop loss. We may have had up to 50% bud damage and still produce a full crop by simply adjusting the number of buds retained after pruning.”
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