Posted: Thursday, January 24, 2013 12:00 PM
Sean Ellis/Capital Press
A vineyard near Caldwell, Idaho, is cover in snow in early January. Unusually cold temperatures in the region have wine grape growers concerned about the impact on their vines.
Low temperatures persist for weeks in Idaho's wine country
By SEAN ELLIS
CALDWELL, Idaho -- A deep freeze that has persisted in the Treasure Valley for most of January has grape growers and wineries concerned about the impact to plants.
"I expect some damage. We're crossing our fingers here," said Ron Bitner, owner of Bitner Vineyards in Caldwell in southwestern Idaho.
Temperatures have been as much as 25 degrees below normal for the past three weeks and dipped to minus 4 degrees the past three days in Caldwell, which is in the heart of Idaho's wine country.
The cold "has been very persistent the last 10 days, with lows between zero and minus 5 the whole time," said Les Colin, a meteorologist with the National Weather Service's Boise office.
Colin said temperatures fell to as low as minus 9 in lower elevations in places like Weiser and Ontario, Ore., for a few nights.
"That's starting to push the envelope here in Idaho," Bitner said. "It's too early to panic, but definitely there is some concern."
Temperatures at University of Idaho's Parma research station have been well below zero for several days, but it's been much colder in some pockets in the area, said professor Essie Fallahi, UI's project leader on fruit crops.
"Any time the temperature gets down to that range, it might get to the tolerance limits of some plants," he said. "I'm kind of worried about some of those places in lower areas where it can get (several) degrees colder."
Colin said the weather is expected to start getting quite a bit warmer later in the week, but winegrape growers are concerned about the damage that has already been done.
Bitner said there have been three really cold winters in the area during the 32 years he has been growing winegrapes here and this year is the second coldest behind 1991, when temperatures stayed well below zero for an extended period of time and killed some grapevines all the way to the ground.
Bitner had to retrain his plants following that cold snap, a process he said can cost about as much as planting new ones, and his vines produced about one ton per acre instead of the normal three tons per acre the next season.
As the mercury flirted with zero for several days in early January, wine industry leaders said they were keeping an eye on temperatures but weren't overly worried. But it's gotten even colder since then and now they're starting to express real concern.
Vines in the area are in deep dormancy and are more cold hardy this time of year because they have had time to adjust to the cold, Fallahi said.
Even then, he added, he's starting to get concerned about the unusually low temperatures.
According to the NWS, the average temperature for the month is on track to make this January the fifth coldest on record dating back to 1865.
The average temperature is a full 15 degrees below normal.
Bitner said the length of the current cold snap is also a concern.
"The longer it goes on, the worse it can be," he said.