Winter Inflicts Damage on Cool-Climate Wine Regions

(WineSpectator) - A relentless winter with dangerously low temperatures has killed vine buds and wiped out a significant portion of this year's potential wine grape crop in parts of the Finger Lakes, Ontario and Michigan. Growers are assessing the damage and hoping to coax the most fruitful growth possible out of surviving plant material in the spring. But they fear the cold may have killed some vines too.

"I don't know about you, but it's been sunny and 70 up here most of the winter!" joked Tom Higgins, owner of Heart & Hands Wine Company in New York's Finger Lakes. As residents of the Northeast and Midwest know, it's been anything but in recent months as temperatures reached repeated lows below zero, even as low as -29° F in some growing areas. The weather severely tested vines in cool-climate wine regions. Some areas suffered nearly 100 percent bud damage on vinifera vines—a potentially disastrous loss in crop.

Vinifera varieties can usually shrug off cold temperatures during winter dormancy, but depending on the grape, the region and the duration of the cold snap, buds start dying at between -8 and -14° F. Among the common varieties in the regions hit, Merlot and Sauvignon Blanc suffer more readily than Riesling and Cabernet Franc. When buds die, crop is obviously reduced. Secondary buds may grow later, but these are less fruitful.

And the damage might be worse. Dead buds mean one bad vintage; dead vines take years to replace. "Over 50 percent bud injury in a certain variety, then we start to think there's going to be some trunk injury," said Hans Walter-Peterson, a professor with Cornell's Viticulture and Enology program who has analyzed 12,000 cane samples in the Finger Lakes so far this winter. "Is it enough to kill the vine?" That's the big unknown. "Think of [a vine's vascular system] as a bunch of straws. If you gum up enough of those straws, the vine can't pull up all the water and nutrients that it needs, and it can collapse." Healthy-looking vines may be dead inside, but won't keel over until the stress of summer.