Researchers study cold hardiness of Idaho wine grapes
By SEAN ELLIS
BOISE -- Boise State University researchers are trying to help Idaho's wine grape industry better prepare for extreme cold temperatures.
"Extreme cold is probably the No. 1 issue for damage and loss of grapes in this area," said Jacob Cragin, a BSU graduate student who is leading the project, which is financed by a $23,000 specialty crop grant awarded through the Idaho State Department of Agriculture.
Idaho grape growers don't get the same disease pressure some other states do because of the cold conditions here, he said, "but most of our problems come from cold damage."
The grant will allow researchers to determine the cold hardiness of two of the most widely planted cultivars in the Snake River Valley American Viticultural Area, Cabernet Sauvignon and Chardonnay.
Wine grapes need some exposure to cold to go dormant and rebud in the spring but the vine can be severely injured by cold depending on the stage and depth of its dormancy at the time of exposure.
Cold is the major cause of losses for Idaho growers, said Marcelo Serpe, a professor in BSU's biological sciences department.
"Late and very early cold events cause the short growing season here," he said. "It's probably the most limiting factor in growing grapes in this area."
The grant will allow researchers to determine the effective cold temperatures that release dormancy and the relationship between the depth of dormancy and cold hardiness.
Grapes change their ability to tolerate cold throughout the year, and researchers will try to determine the grapes' sensitivity to cold at different times of the year.
To do that, the cultivars will be exposed to low temperatures under natural conditions and in controlled environments.
The goal is to correlate the data with weather conditions and create a mathematical model that predicts cold hardiness based on ambient temperatures. If the forecast temperature is going to be below the critical temperature a certain grape can tolerate, Idaho growers can be alerted to take precautions to avoid losses.
The model would be placed on the Idaho Wine Commission website and include bi-weekly temperature data updates along with cold hardiness data.
"We're trying to give growers some more tools to prevent crop loss," Cragin said.