PROSSER, Wash. -- The sun beats down as researcher Markus Keller leans in to inspect his experimental vineyard.
“As you can see here, there’s a lot of flowers forming on the different shoots,” Keller says.
The grape leaves hang down like a curtain over the rows of vines. This year’s crop looks to be strong.
For connoisseurs of fine grape jellies and juices, this is a reason to rejoice. For collectors of fine wines? Not so much.
These are Concord grapes -- which make up 99 percent of the variety that go in to juice and jelly production, Keller says.
Turns out, Concord grapes – first cultivated in the Massachusetts village of Concord – flourish in Washington’s climate east of the Cascades.
But that climate is changing. Summers may get too warm for these grapes in Eastern Washington, where nearly half the Concord grapes in the United States are grown these days.
Keller studies viticulture at Washington State University. He’s been looking into ways to continue growing juice grapes a warming climate.
Central Washington has experienced a warming trend over the last 30 years. That’s according to data from the National Climate Data Center. Scientists expect that trend to continue.
Keller: “I think that in 50 years, maybe 40, we will have not much left of our juice grape industry.”
Craig Bardwell with the National Grape Co-op in Grandview, Washington says there's one main problem with summers that are too hot:
"Color. And color is a very important part of the juice,” Bardwell says.
People want their grape juice to be purple. That’s the color of grape juice you picture at the breakfast table.
Too much heat means grapes stay greener.
“And that does decrease our color intensity. And there’s not really anything we can do about that,” Bardwell says.
Juice grapes also use two to three times the amount of water as wine grapes. That’s because they have a much larger canopy of leaves and are more heavily irrigated.
Researchers are trying to figure out how little water the grapes can get by on. Too little water, and the vines don’t produce as many grapes.
As far as the heat problem is concerned: Keller is experimenting with a newer juice grape variety called sunbelt. It's a hybrid developed by crossing a Concord grape vine with another variety.
“We don’t know what the other parent is. It’s kind of an illegitimate child,” Keller says with a chuckle.
The sunbelt variety is from Arkansas. Like its name suggests, it handles heat well. But it doesn’t produce the same large crops as Concord grapes.
One idea is to stagger rows of sunbelt grape vines with rows of Concords. It may be a way to save the juice grape crop.
Another possibility that Keller is exploring: planting crops at higher elevations where temperatures would be cooler.
“People talk about the wine all the time and forget that Concord is our most widely planted variety, still,” Keller says.
Keller said that’s why it’s important to find a solution before things get too hot.