Updated

A deep freeze that already may have ruined as much as three-quarters of California's citrus crop threatened the few surviving fruits as the region endured a fourth night of icy temperatures.

A large arctic air mass continued hovering over the western states early Tuesday morning, icing up the San Joaquin Valley's billion-dollar orange and lemon crop. Other crops, including avocados and strawberries, also have suffered damage in the cold snap, state agricultural officials said.

"This is one of those freezes that, unfortunately, we'll all remember," California Department of Food and Agriculture Secretary A.G. Kawamura said.

Philip LoBue, a Tulare County farmer and chairman of California Citrus Mutual, a 2,000-member trade organization, estimated Monday that growers already had lost between 50 and 75 percent of their citrus crops in temperatures that dipped into the teens. The fruits are threatened whenever the mercury falls below 28 degrees.

"When you're already cutting ice within the oranges, you know those are gone," LoBue said.

While growers hastened to pick as much of the $960 million in fruit still hanging on trees before the cold hit Friday, an industry labor shortage meant much of the crop went unharvested, LoBue said.

The National Weather Service predicted a very gradual warming trend during the week, although a freeze warning remains in effect in the San Joaquin Valley through Wednesday morning.

Damages from the latest freeze will likely surpass those caused by a three-day freeze in December 1998 that destroyed 85 percent of California's citrus crop, a loss valued at $700 million, Kawamura said.

The full impact of the freeze would not be known until inspectors have a chance to check fruit for damage, state agricultural officials said. In the meantime, fruit packers were asked to keep produce harvested during the freeze on hold for five days to monitor for quality problems and keep damaged fruit off store shelves.

Jim Bagnall, an NWS meteorologist based in Hanford, said the unusual weather pattern bringing such low temperatures to California only comes about once every eight years.

"It's a rare pattern that we get an arctic outbreak like that," Bagnall said. "It's likely to be the coldest that we experience this season."

After a weeklong freeze in 1990, the industry took two years to recover, said Joel Nelsen, president of California Citrus Mutual.

The extreme cold also was being blamed for burst pipes that cut off water to residents and business in several California communities, including Bakersfield, where 24-degree temperatures reported Monday broke the previous record low set in 1972 by two degrees.