MIAMI (Reuters)—Plunging overnight temperatures froze fruit in Florida's citrus growing regions overnight, inflicting varying damage to the orange crop, producers said Monday, although the losses did not appear catastrophic.

"Growers are cutting ice today," Ray Royce, executive director of the Highlands County Citrus Growers Assn. in central Florida, told Reuters, as anxious Florida citrus farmers sliced fruit with knives to check for freeze damage.

Florida produces more than three-quarters of the U.S. orange crop and its $9.3 billion citrus industry accounts for about 40% of the world's orange juice supply.

But the Sunshine State, which is famous for its beaches, fruits and abundant sunshine, has been hit over the past week by successive blasts of arctic air that brought snow, ice and transport chaos to more northern parts of the United States.

AccuWeather.com quoted its agricultural meteorologist Dale Mohler as saying the freeze "this morning could be the worst the area has seen since 1989."

He projected that losses in the citrus crop may approach 10%. The U.S. Agriculture Department forecast the 2009/10 crop at 135 million 90-pound boxes, the second lowest since 2000.

Analysts said another area of concern would be if the freeze affects the ability of citrus trees, already hard hit by diseases like citrus greening and citrus canker, to flower for the 2010-11 crop. Cumulatively, the multiple nights of unusually low freezing temperatures in Florida had taken their toll on the state's citrus groves at the peak of the harvest, directly damaging some fresh fruit and also reducing juice content, growers said.

"I would say that there is probably widespread light damage and some considerable to heavy fruit damage," said Mr. Royce, whose organization represents growers in the second largest citrus producing county in Florida.

Several frigid nights last week had largely spared the bulk of Florida's citrus crop. But overnight Sunday saw the harshest freeze yet, growers said, with many growing areas remaining for most of the night below the key 28 degrees Fahrenheit level. Typically, citrus crops get damaged if temperatures fall to 28 degrees Fahrenheit or below for four or more hours.

"We definitely had our coldest weather for the largest duration so far ... we are going to get more fruit damage," Mr. Royce said.

'Not catastrophic'

Grower John Arnold of the Showcase of Citrus in south Lake County, who grows more than 50 varieties on 1,000 acres, said his crop had suffered from the freeze.

"What I'm seeing here is 30% penetration of ice in the fruit," he told Reuters. "But it is not catastrophic, we still have citrus that can be picked."

Mr. Arnold said it was the most delicate, sweetest varieties, such as Honey tangerines and navel oranges, that had been worst affected by the freeze.

Freeze-damaged fruit cannot be marketed as fresh fruit and also loses some of its juice.

"There is no doubt we will see juice reduction in a lot of fruit, to what extent I don't know," Highlands County's Mr. Royce said.

But, he added, "In the great overall scheme of things, we are not at some catastrophic level."

Growers say it could be several weeks before the full extent of the freeze damage is known to the current crop.

"The worst of the cold should be past for Floridians," AccuWeather.com said in a report. "Temperatures will begin to rebound a bit across the Southeast today, but the unusual cold will not be completely erased until later this week."