LEXINGTON, Ky. — It may be the middle of summer, but last winter’s colder-than-normal conditions are still creating problems for Kentucky farmers, especially those in the vineyard business.

As grape harvest approaches, producers are finding some varieties are showing extensive damage caused by the hard winter. Patsy Wilson, viticulturist for the University of Kentucky (UK) College of Agriculture, Food and Environment, said the amount of damage varies from vineyard to vineyard but for some, the effects could be felt for some time to come.

She emphasized there are two primary types of grapes grown in Kentucky: hybrids and European grapes. It is the European varieties that don’t do well in cold temperatures, especially the kind of cold from last winter. "These European, or what we often call vitis vinifera, grapes really aren’t that cold tolerant past zero degrees," said Wilson. "When we start getting into those negatives, we really knew that we were going to start having quite a bit of freeze damage."

At that point it became a waiting game to see how much damage had occurred, Wilson added – and as the year began to unfold experts realized there was significant damage to the European varieties. "There are a lot of factors that go into that kind of damage, like what kind of conditions the vines were in headed into the winter," she explained. "So that’s why it’s really variable across the state as to how much damage each specific vineyard had."

The vineyard location also plays a role in the amount of harm, which is broken down into two levels, according to Wilson: one being vines that will suffer damage for the current season, and those that have suffered permanent damage.

"We had several weather events in early 2014 where we had a slight warming followed by extended periods of below-freezing temperatures," she said. "Cold, tender vinifera vines and vines that were weak going into the freeze event were likely going to have moderate to severe damage."

Producers who have lost vines will ultimately have to start from scratch, and that means at least a four-year wait to harvest grapes from those replacement vines. But the news isn’t all bad.

Hybrid varieties have fared much better in Kentucky’s climate and many producers grow multiple varieties of grapes including those hybrids. Wilson said those varieties, even though some also suffered damage, will likely produce near-normal levels this year.

"Although some hybrids have the potential for damage at the temperatures we saw in January, they have highly fruitful secondary shoots," she said.

"This means that in the event that the primary bud is killed, there is still a secondary bud that will likely push out a shoot that will bear fruit.

"Although vinifera vines also have a compound bud, if a secondary bud does push out it is generally not fruitful. This is one of the main reasons we recommend hybrid grapes for this region."

Wilson said when she works with new growers who are establishing vineyards, she recommends they plant hybrid grapes first and the European varieties as a secondary choice. She tells producers upfront that in the event of winters such as the one this year, there is the potential vines could be lost. But losses can occur even in normal winters. "If you have a European grapevine planting, you’re generally going to have to replace some of those vines throughout the vineyard. It’s just a part of growing European grapes in Kentucky," explained Wilson.

Not all the European varieties were lost. According to information from UK, the vinifera varieties that did have some surviving vines were Rkatsiteli, Riesling, Pinot Gris, Chardonnay and Lemberger. But for those producers growing the varieties Cabernet Franc, Cabernet Sauvignon, Viognier, Malbec, Tannat, Petite Verdot, Mourvedre and Petite Manseng, they lost nearly 100 percent of buds.

Not only will this affect the vineyards, but the wineries that use Kentucky grapes will also suffer. And even for those growers with mixed varieties, the European grades generally bring a higher price. Wilson said the vinifera grapes also add complexity and depth to the wines in which they are used. That is not to say the hybrids are less of a quality product, because they are not, said Wilson. But there are reasons to grow both.

It is too soon to know how much of a monetary loss this situation will present but with the grape harvest about to begin, producers will have a better idea later in the fall.