Agriculture officials have collected samples of citrus in the Redlands area to determine whether fruit has been harmed during the current cold snap, but they said Monday it was "too early to tell" whether local crops have sustained costly damage.
More freezing or below freezing conditions are expected Monday night in wind-sheltered areas of Redlands and Mentone, citrus and weather officials said Monday. It should be the last of five consecutive nights of potentially damaging cold for citrus growers, according to forecasters.
The citrus crop in San Bernardino County was worth an estimated $9.8 million in 2011, the last year figures were available for, County Agricultural Commissioner John Gardner said.
Citrus growers in Redlands and Mentone have been spending sleepless nights since last week as overnight temperatures have plunged into the 20s and 30s, because sustained freezing conditions can damage vulnerable oranges, grapefruits and lemons.
Early Sunday Jan. 13, some growers in east Redlands and Mentone lit kerosene and oil-burning smudge pots to ward off the freeze, in groves including locations off Citrus Avenue, Nice Avenue and Third Street.
The current cold snap is a concern for growers statewide, with an estimated $1.5 billion in fruit still ripening in groves from the Inland Empire to the Central Valley, according to the growers association California Citrus Mutual, which is based in Tulare County in the San Joaquin Valley.
"After four consecutive nights of temperatures in the 20s and low 30s the citrus crop will see some damage, the extent of which will become clear in the coming days," Joel Nelsen of California Citrus Mutual said in Monday morning's frost report.
The growers association calls the current cold snap "a 5-day freeze event." Monday night is expected to be the last with potential freezing conditions. It has been slightly colder in the San Joaquin Valley than it has in Redlands and Mentone, according to California Citrus Mutual.
Bob Knight, a Redlands-area grower who founded the Inland Orange Conservancy, said he's been running water on his 37 acres in Crafton and San Timoteo Canyon the past three nights.
Knight said he is expecting to see some damage to citrus in the colder pockets of San Timoteo Canyon.
"I'm on 37 acres, commercial," Knight said. "We've been running water but we don't have wind machines. I have two blocks, here in Crafton and over in San Timoteo Canyon, which is typically the coldest part of Redlands.
"We had temperatures at 26, for hours at a time, the past three nights," Knight said. "I think there will be pockets that get some damage in the Redlands and Loma Linda area. It wasn't that cold up on my Crafton section."
Growers work about 2,500 acres of citrus in Redlands, Mentone, Crafton and some portions of Highland, Gayle Covey, executive director of the San Bernardino Farm Bureau, said Monday.
The Farm Bureau represents all agriculture in San Bernardino County, including the citrus growers in the East Valley area, Covey said.
"Since Friday it's been in the low 20s at times, so growers have been on high alert," Covey said. "It's no longer an issue of frost protection. Now they're combatting the freeze, with water and wind machines."
Asked about the smudging in east Redlands and Mentone early Sunday, Covey said the use of smudge pots is less prevalent these days, and more growers use water and wind machines to keep ground and grove temperatures near 30 degrees.
As far as potential freeze damage to citrus, "it's too early to tell," Covey said. "They have to get through it, and wait until the temperatures have risen to see if there's been any damage."
Samples have been collected from three different groves in areas that are generally colder, including Nevada and Palmetto in west Redlands, and in San Timoteo Canyon, Gardner, the county agricultural commissioner, said in a phone interview.
"We typically wait until about three days after the sample has been pulled, to see if there's damage," Gardner said. "We slice the fruit and spread the segments and look for sugar crystals that form if the cells have ruptured.
"If the cells rupture and release the juice, it leaves sugar crystals," Gardner said. "The end result is the orange is dry on the inside, all the cells have ruptured. You cut it open and it's just a mass a broken cells and all dry on the interior."
Temperatures below 28 are the real concern for growers, Gardner said.
"I do know it was down below 28 for a few hours these past few nights," Gardner said. "Down to 24 for a couple hours and you will get damage to the fruit.
"Whenever it gets down to 30 at night they're checking to make sure it won't be going down to 28 or lower - six to eight hours at 28 can cause damage, and as it goes lower the time for potential damage decreases."
Flowing water in the groves is intended to raise ground temperatures, and water that freezes results in ice that also acts as an insulator, Gardner said.
Asked about smudging in groves early Sunday, Gardner said, "We see them every couple of years when we get short periods of cold weather that are cold enough to be a concern, temps down to the mid 20s.
"The smudge pots today are not as dirty as those of the past," Gardner said. "They burn kerosene or fuel oil, and we don't see as much smoke as we used to."
Redlands and Mentone can expect temperatures right around freezing or just below freezing Monday night into Tuesday morning, Cynthia Palmer, a meteorologist with the National Weather Service, said in a phone interview Monday afternoon.
"We have a high wind warning for that area, and the winds will actually make it a little warmer," Palmer said. "They mix the atmosphere so the cold air won't settle. That said, Redlands and Mentone are in a wind-sheltered area due to the mountains nearby.
"For Redlands and Mentone we're looking at a low of 30 to 32 tonight," Palmer said. "It will be the last of the really cold nights. . . . The wind-sheltered areas can get colder and we are advising of the potential for frost. So we are suggesting people take steps to protect sensitive plants and crops, including citrus."
Tuesday night the lows should be in the upper 30s to low 40s, and by Wednesday lows are expected in the 40s, Palmer said.
One of the last times growers lit smudge pots in east Redlands and Mentone was during a cold snap in January 2007. Growers lost 60 percent of the state's citrus crop due to freezing temps that month, according to industry officials.
East Redlands and Mentone are in San Bernardino County, about 70 miles east of downtown Los Angeles.