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'Great Chill' a Blessing to Blueberry, Peach Growers

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Photo: Scott Bauer, USDA-ARS

The cold winter gives blueberry growers a brighter outlook for the $9 million Georgia crop.

Donnie Morris doesn't describe the frigid weather of late January and early February the way many Georgians would. "I don't know any other way to say it: it's just wonderful," Morris said.

For Morris' more than 200 acres of blueberries near Baxley, Ga., the almost constant cold was exactly what they needed. "We need about 700 chill hours," he said, "and that's about what we have now."

Blueberries, peaches and other fruits need a certain number of chill hours, or hours below 45 degrees Fahrenheit, between Oct. 1 and Feb. 15. In the heart of blueberry country, Alma, Ga., had 790 chill hours as of Feb. 6.

Winter Just in Time

For Morris and other growers, the hard winter came just in time. "Three weeks ago the situation looked grim," said Gerard Krewer, a small fruits specialist with the University of Georgia College of Agricultural and Environmental Sciences.

"Before the 'great chill,' the weather had been so mild," Krewer said. "The low-chill varieties of Southern highbush and rabbiteye blueberries were on the verge of an extremely early bloom. They would have been in great danger of freeze damage."

Almost all of the state's 4,400 acres of blueberries are in south Georgia. But from mid-January through the first week of February, though, the chill hours in the area mounted fast.

'It Was Like a Miracle'

"We like to see 750 hours or more for most varieties, and we've got that now," Krewer said. "The 'great chill' put the low-chill varieties back into dormancy and satisfied the higher-chill varieties' requirements. It was like a miracle. We couldn't have asked for better weather."

Blueberries will still bloom when chill hours are low, Krewer said. But the blooming will be strung out over a longer time. That makes it even more vulnerable to late freezes and makes it harder to control insects like thrips and gall midges.

"The more compact blooming time you have when the chill hour requirements are met usually improves pollination, since more varieties are blooming at the same time," he said.

Peaches Helped, Too

The shivery days were a blessing to peach growers, too, said UGA horticulturist Kathryn Taylor.

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Photo: Kathryn Taylor

Getting enough chill hours allows peach trees to produce plenty of blossoms and, ultimately, a bountiful harvest of sweet Georgia peaches.

"We had been behind in chill hours since mid-December," Taylor said.
"We're still behind the 45-year average. But for most varieties, we have enough chill hours now to meet the minimum requirements."

Peaches are more demanding than blueberries when it comes to chill hours. Coming up just 100 hours short can cause a major crop failure in many varieties.

"We have varieties with chilling requirements ranging from 400 hours up to 1,000 hours," Taylor said. "We're at about 900 hours at Fort Valley now. That probably takes care of 95 percent of our varieties."

Growers would like to get the 100 hours or so the highest-chilling varieties need. "But even if we get no more chill hours," Taylor said, "most of our growers will be happy campers."

One of Two Nervous Times

In south Georgia, where about 10 percent of the Georgia crop is grown, Brooks County has now had 670 chill hours. "That will take care of the latest varieties," Taylor said.

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Photo: Scott Bauer, USDA-ARS

Georgia peach growers' chances for a strong crop have been boosted by the winter chill. In a good year, the state's peach crop brings farmers about $35 million.

Peach growers needed the cold weather badly, coming off a year with very few chill hours, which raised their production costs. "Last year we were way behind," Taylor said. "We never got enough chill hours."

This winter's cold weather has gotten growers past one of two nervous times in the peach growing season.

"Now the buds are dormant and are just sitting there 'counting' heat units," Taylor said. "When they get enough heat units, they'll begin to swell and then start blooming."

When the flowering process starts, the blooms will be susceptible to late frosts. Temperatures 28 degrees and lower can cause serious damage to peach blossoms and greatly reduce the crop.

"Our growers will be holding their breath until mid-April looking at frost events," Taylor said.

(Dan Rahn is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)

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