LOS ANGELES, Jan 14 (Reuters) - A California cold snap that plunged temperatures below freezing for several days appears to have caused minimal harm to orange and strawberry harvests so far but the full extent of crop damage will remain uncertain for at least a week, farm groups said on Monday.
Below-normal temperatures chilled much of the state for a fifth day on Monday, falling to record lows again in parts of California. But warmer weather was expected to return on Tuesday, promising a break for farmers who have scrambled since last week to protect their orchards and fields from frost.
Some mandarin oranges were confirmed to have been damaged by freezing temperatures in the San Joaquin Valley, the heart of the state's citrus-growing region in central California, said Alyssa Houtby, spokeswoman for the trade association California Citrus Mutual.
But Houtby said farmers did not anticipate significant losses.
"We don't expect consumers to notice a price increase or any shortage in supply," she said. About a quarter of California's mandarin crop was lost to frost last year.
Navel oranges and the slightly more cold-susceptible mandarins make up the bulk of California's citrus production, an industry worth $2 billion a year, and the latest cold snap struck just as harvest operations were ramping up for both.
Prolonged exposure to temperatures below 28 degrees Fahrenheit can spoil the crops. The temperature fell into the low- to mid-20s across much of the San Joaquin Valley early Monday.
But Houtby said farmers have taken steps to safeguard the estimated $1.5 billion worth of fruit that remains to be picked. In recent days, growers spent some $17.5 million running fans and pumping extra water through their orchards, trying to raise temperatures just enough to fend off damage, she said.
Meanwhile, farmers in Ventura County, just north of Los Angeles, labored to save their strawberry crops.
California's strawberries, valued at roughly $2.2 billion a year, are especially vulnerable to cold snaps, with plants generally unable to withstand extended exposure to temperatures lower than 34 degrees Fahrenheit, said Carolyn O'Donnell of the California Strawberry Commission.
Much of the state's 855,000-ton annual strawberry yield comes from Watsonville, just south of San Jose, but the harvesting season there is still months away.
The current U.S. fresh strawberry supply depends on farmers in Ventura County, who produce far less.
Strawberry farmers ran fans and flew helicopters over their fields to increase airflow and raise the temperatures by a few, critical degrees. It will take one to two weeks before the berries become withered or show other signs of any damage they might have sustained, O'Donnell said. (Editing by Steve Gorman and Bill Trott)