Freezing Temperatures Threaten Blueberry Crop

By for CAES News

Georgia's freaky freezing temperatures haven't hurt the state's blueberry crop yet. But if warm weather arrives soon, it could set up this year's blueberry crop for significant freeze damage later.

"I don't think the cold weather has hurt the blueberry crop so far, but it's sure setting us up for a dangerous situation," said Scott NeSmith, a research horticulturist with the University of Georgia College of Agricultural and Environmental Sciences. "Right now, the blueberries have received more chill hours than they need at this point in the season."

They've Gotta Have the Cold

Blueberry plants need cold weather to produce blooms and then fruit. This cold weather requirement is called chill hours. Once the plant gets the required number of chill hours, it's ready to break bud and produce blooms.

"If the weather warms up now, the plants are really going to start blooming fast and this sets up a danger for possible freeze damage later," NeSmith said. "So if we go through two weeks of warm weather, we run the danger of getting early bloom before the frost damage is over."

NeSmith said Georgia blueberry growers faced the opposite problem last year.

"In 1999, we had a record lack of chill hours, just 200, for the first week of January," he said. "The plants weren't getting the chill hours they needed to bloom adequately. This was a very low number of chill hours compared to the historical number of 400 chill hours for the same time of year."

Today, NeSmith keeps a close eye on the number of chill hours using data from UGA's Georgia Automated Environmental Monitoring Network website <>.

Too Many Chill Hours

"Here in Spalding County, we have normally accumulated 400 to 500 chill hours at this time of year," he said. "But this year, we already have more than 900 chill hours, which is about a 40 percent increase in chilling."

NeSmith says having too many chill hours is rarely a problem. "This only happens five to 10 percent of the time," he said. "It's almost unheard of for us to have this problem."

The largest concentration of commercial blueberry orchards in Georgia is located in the southeastern corner in Appling, Bacon, Clinch, Pierce and Ware counties, with additional growers sprinkled across the state. Georgia ranks third in the nation in blueberry production with more than 4,500 acres.

NeSmith and other UGA horticulturists plan to share their concerns with Georgia blueberry growers during the Georgia Fruit and Vegetable Conference set for this weekend in Savannah.

"It's a very scary situation because winter has been shifted back," he said. "It's not any one cold event we've faced that has caused this dilemma. It's the amount of total cold weather we've been having. The cold hasn't hurt us so far, but it sure has put us in a precarious position."

Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.