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WESTFIELD – Some 1,500 times a week, grape researcher Luke Haggerty takes penetrating looks at grape buds from vineyards along the Lake Erie shoreline in Chautauqua County.

Using a razor blade, the Cornell Cooperative Extension specialist slices each bud in two and examines it under a microscope.

If he sees green, that means the tissue remains alive. But brown spells death.

For grape growers, this white winter of frigid temperatures has led to a lot of dead buds, mainly from the Riesling, Cabernet Sauvignon and Pinot Gris vines meant for making wines. Growers are bracing for losses of up to 90 percent of some of their most-prized varieties.

“This year is particularly bad,” said Haggerty, who has inspected more than 4,300 buds since last month, giving him a good sense of the winter’s damage so far.

Haggerty, a specialist with Cornell’s Lake Erie Regional Grape Program, called the damage the worst the region’s vineyards have suffered in a dozen or more years. The bud damage means a smaller crop for wine grapes this year, while the prospects for grapes used for juices and jellies seem better.

How grapes fare this winter is no small matter in Chautauqua County.

“We’re a $340 million industry in the Concord Grape Belt that supports a lot of jobs, economic impact and in the taxes we pay,” said Dave Momberger, the general manager of Grower’s Grape Juice Cooperative in Westfield.

Some worry how a bad year for wine grapes might affect the wine tourism industry that has blossomed in the county over the past decade.

This is the first full year for the Lake Erie Grape Discovery Center, which opened last fall in Westfield. A sign outside the center directs visitors to two dozen nearby wineries. Tourism pumps dollars into local hotels, restaurants and stores, and also generates tax revenue.

So Haggerty’s reports can be tough to bear for vintners like Mario Mazza, owner of Mazza Vineyards in North East, Pa., who cultivates many of the most sensitive wine grapes.

“The persistent cold we’ve had is definitely going to be detrimental to the vineyards,” Mazza said. “We don’t know exactly what the final picture is going to look like. I think it’s going to be very significant.”

Assessing the damage is not an exact science. There can be stark differences in temperatures from one vineyard to the next because of elevation or air patterns. The duration of the cold plays a role in the extent of damage.

There is a glimmer of hope. The bitter cold struck when the vines are in their most dormant and hardiest phase.

And the most-threatened grape varieties account for a smaller part of the grape belt’s economic livelihood.

Only about 4 percent to 6 percent of the 33,000 acres are for vinifera or hybrid grapes used for wine. The rest – like the native Concord and Niagara varieties – are mostly used in juices and jellies. The Concord variety shows a damage rate of 13 percent, the lowest of the nine grape varieties Haggerty analyzed last month and only barely above its normal 10 percent mortality rate.

Growers need only remember 2012, when a late April freeze wreaked havoc on the region’s grapevines, to appreciate the inherent risk for anyone who grows crops.

Many grape growers readily accept dead grape buds as a risk of doing business in a cold climate – if only they could know that’s where the damage has stopped.

When that’s the case, the cold winter means a year’s setback.

But bud damage can be a harbinger of worse news: trunk death. The prolonged extreme cold, depending upon the hardiness of the vine, can penetrate and freeze the vital circulatory system, killing the vine.

That scenario would mean a three- to five-year setback, because growers would have to regrow the vine.

In deep winter, grapevines have some protective mechanisms. “Basically, a plant will become more and more resistant to cold as the winter deepens,” said Bill Merritt, owner of Merritt Estate Winery in Forestville. “They gain hardiness faster than they lose it.”

“If your vines have been strained, if they are overcropped and not taken care of, they will suffer more,” he said.

The biggest problems arise during widely fluctuating temperatures in late winter or early spring, when sap inside the plant is on the move, Merritt said. Those are the days when the temperature spikes to 60 one day, then drops to 5 degrees a few days later.

“That’s just brutal,” Merritt said. Had that happened, “it would have been much more disastrous.”

Buds have the ability to “supercool” and remain liquid, even at temperatures below zero. Trunks can avoid freezing by pushing water out of cellular tissues – a process of self-dehydration.

Grapevines are also unaffected by wind chills.

Still, there’s a limit.

“All grape varieties have a breaking point, where cell tissues can no longer handle lowering subzero temperatures and these plant tissues freeze,” Haggerty said.

Wine industry affected

In the most recent sampling, vineyards in Erie County, Pa., seemed to be somewhat harder hit than vineyards in New York closer to the Lake Erie shore, where temperatures did not get as cold, Haggerty said.

In the harder-hit areas, 80 percent to 90 percent of the wine grape buds have been killed. The figures range from 60 percent to 70 percent in other areas, according to Haggerty.

The varieties under the most threat – mainly European species like Pinot, Riesling and Cabernet – are found along the shorelines of Lakes Erie and Ontario.

“It’s probably going to affect the wine industry more than the juice grapes,” Mazza said.

January’s assessment showed that Cabernet Franc and Sauvignon varieties experienced rates of bud mortality exceeding 70 percent. Other tender wine grapes like Pinot Gris and Riesling both were above 60 percent dead, according to Haggerty. They’re at risk when temperatures drop to between 0 and minus 10 degrees.

Hardier native varieties like Concord and Niagara grapes – which are mainly considered juice grapes – are at risk when temperatures dip to minus 15 degrees or lower. They seem to be faring much better against the cold this winter.

Grape growers in Western New York are not alone in worrying about damage to vineyards.

A Niagara-on-the-Lake, Ont., grape grower recently told CBC News that he had lost nearly all of his Syrah and Sauvignon Blanc crops for the year and said that 2014 would be remembered in wine circles as “the year of the grape-killer cold.”

The winter’s impact in the Finger Lakes region has been mixed.

Bob Madill, co-chairman for the Finger Lakes Wine Alliance board of directors, said vineyards closest to the lakes seemed to weather the winter . Others, especially those on the northern edges of the Finger Lakes, such as near Geneva, were hit harder.

Madill predicted a greater demand for the Finger Lakes grapes that survive, especially varieties like Riesling, from wineries in Western New York, Pennsylvania and Ohio, where vineyards were hit hardest.

Game plans

So what can worried grape growers in Western New York do?

Growers like Mazza and Frank Johnson, proprietor of Johnson Estates winery in Westfield, are drawing up their game plans for the 2014 season.

“There are some things that can be done for mitigation,” Mazza said.

When late-winter pruning begins in earnest about a month or so from now, many growers will try a few tricks on vines where the damage was limited to about 30 percent or less.

“You can somewhat compensate for that by leaving more buds up there when you prune,” Johnson said of one option.

Each bud pack has three buds – primary, secondary and tertiary – that appear successively if a preceding bud is damaged. In many cases, however, experts are finding the cold damage has afflicted each of the three buds.

There’s also another method.

“This year, everyone will be saving their suckers,” Haggerty said. These new shoots from the main trunk can hedge against a catastrophic vine collapse in mid-summer.

But the bag of tricks isn’t very deep.

“I’m really nervous right now,” said Jonathan Oakes, a fourth-generation fruit farmer turned winemaker at Leonard Oakes Estate Winery in Medina, which grows Cabernet Franc, Sauvignon and Pinot Noir varieties. “I think we’re all in the same boat.”

To make matters worse, unless a frozen trunk is split open, the cold damage can be hidden until well into the growing season.

Haggerty said the vine grows as usual in the spring until water becomes scarce during midsummer. Then, it collapses and dies. Winter damage “won’t be fully known until July,” Johnson said.

Experts say vines with more than 50 percent bud damage most likely will show irreparable trunk damage.

For those growers heavily invested in wine grapes, dealing with 90 percent bud loss and potential trunk damage is daunting. But according to Johnson, it “comes with the territory.”

“If you’re going to grow these European varieties,” he explained, “you’re going to get dinged from time to time.”

email: tpignataro@buffnews.com