While Southern Californians have enjoyed balmy weather over the last week, some citrus growers in the San Joaquin Valley are still coping with the aftermath of harrowing cold last month, the longest stretch of subfreezing temperatures on record in the area. In general, the state's commercial citrus industry appears to have escaped without disastrous losses, and this season is shaping up as a good one, but some of the small growers who sell at farmers markets lost significant portions of their crops, and it behooves shoppers to be alert for damaged fruit over the coming weeks.
When temperatures remain below about 28 degrees for more than a few hours, citrus fruits can freeze, causing the tender juice vesicles in the flesh and oil sacs in the rind to rupture. It can take up to several weeks for the damage to become evident as rind blemishes, free-flowing juice and ultimately dried-out pulp.
Such fruit develops off-flavors and becomes inedible, so if damage exceeds the tolerances in California Department of Food and Agriculture standardization regulations, growers have to divert it to juice factories or dump it. In the most severe recent freezes, in 1990, 1998 and 2007, the state's citrus growers lost hundreds of millions of dollars, and thousands of packinghouse and grove workers temporarily lost jobs.
Several times during the month of December, forecasts called for temperatures in the low 20s in the colder districts, which would have caused serious losses, but to growers' great relief, it rarely got below 24 or 25 degrees, and just for brief durations, in most citrus areas. Growers fought the freeze by running irrigation water and wind machines, which pulled down slightly warmer air from the inversion layer a few hundred feet above the ground and raised temperatures several critical degrees.
These measures cost the San Joaquin Valley's commercial citrus growers an estimated $87.8 million in December, for water, fuel and labor, said Bob Blakely, director of industry relations for California Citrus Mutual, a trade association. "On top of that, many growers were getting completely exhausted, putting in a hundred hours a week, making late-night runs to refill fuel tanks, and making emergency repairs to pumps and wind machines," he said.
At least these measures enabled most commercial growers to avoid serious damage to their crops. Robert Milner, an inspector for the Tulare County Agriculture Commissioner's office, said that he recently cut fruit from some of the coldest local groves and found no more than 8% of the fruit to be freeze-damaged.
Many farmers market vendors, however, grow small blocks of citrus for which it is not cost-effective to put up and run wind machines or grow outside prime citrus districts, and so more of them experienced losses.
Troy Regier of Dinuba, who sells mandarins at the Pasadena, Santa Monica and Corona del Mar farmers markets, said he and his parents spent thousands of extra dollars on water last month and derived some benefit from wind machines on neighboring farms but don't have wind machines of their own.
His Gold Nugget mandarins were "wiped out," he said, because they mature later in the season and so did not have high enough levels of sugar, which acts like antifreeze, to be protected when the cold snap hit. His W Murcott mandarins, which are usually harvested starting in late January, experienced some spotty damage to outside rows. His satsumas, which he's been bringing for more than a month, were plenty sweet already, and he had also protected the trees with plastic covers, so the fruit did fine.
Mike Agnew of Lindsay, who sells at the Hollywood farmers market and also does not have wind machines, said he lost half of his Page mandarins and a quarter of his Washington navel oranges on exposed trees. He is very careful not to bring freeze-damaged fruit to farmers markets, and if there's any doubt, he holds off until the fruit's status becomes clear, he added.
The different kinds of citrus fruits vary greatly in their susceptibility to cold injury. Thick-skinned and sweet types, such as oranges, pummelos and grapefruits, are less vulnerable; lemons and limes, which are naturally low in sugar, and mandarins, which have thin skins, are more so.
Mature citrus trees themselves are less often injured by freezes, unless if gets really cold. Young trees are more susceptible and require protection in greenhouses or under plastic covers. Trees of more tropical species, such as limes and pummelos, are more vulnerable, while trees of species that originated in cooler areas, like mandarins and kumquats, are less susceptible.
Traditionally citrus growers in the San Joaquin Valley have planted in or near the southeastern foothills, on "thermal slopes" from which freezing air drains down, providing a crucial advantage on the coldest nights. Most of these plantings survived last month's freeze fairly well, but in recent years sizable citrus acreage has been planted in nontraditional, low-lying areas like Shafter, and some blocks of the later mandarin varieties, particularly, may have sustained more serious damage.
Fortunately, Southern California citrus growers, who provide much of the fruit available at local farmers markets, say that they experienced little or no damage from December's cold nights. And cold that doesn't injure citrus makes it stronger and tastier: Night temperatures in the 30s toughen the rind, deepen the color and sweeten the fruit.
After a slow start for some varieties, partly because of warm nights earlier in the fall, a lot of citrus, both from the San Joaquin Valley and southern districts, has been exceptionally delicious recently, perhaps because of the warm, sunny days and cool nights.
Right now I'd especially recommend Algerian clementines from Bob Polito of Valley Center, at the Santa Monica Wednesday, La Cienega and Venice farmers markets; seedless Kishu mandarins from Jim and Jeanne Davis of De Luz, at Hollywood and Beverly Hills, and from Jim Churchill and Lisa Brenneis, at Ojai; Washington navel and Moro blood oranges from Arnett Farms of Fresno, at Torrance, Brentwood, Studio City, and Mar Vista; and Cocktail grapefruit from Garcia Organic Farm of De Luz, at Santa Monica Wednesday and Saturday downtown.
These should all be good, but as a general rule, after a freeze, farmers market shoppers in particular should be alert to what area citrus comes from, ask vendors if there's any chance it has been damaged, examine the fruit carefully and try samples.