Mercury will rise following freezing weekend

Despite Saturday night being the coldest night of the season so far, most citrus growers escaped any serious damage to their crops.

California Citrus Mutual reported that for the third consecutive night, temperatures failed to reach predicted lows across citrus producing areas, stabilizing in much of the San Joaquin Valley in the upper-20s allowing for frost protection to be successful at preventing any damage to this season’s citrus crop.

While navel oranges can withstand lower temperatures, some mandarin growers may have suffered some crop loss, CCM reported. Mandarins are at risk at sustained temperatures below 31, while navel oranges can take temperatures below 27 right now.

Still, the cold nights have come at a dollar cost. Estimates are it cost $30 an hour to run wind machines and the machines have been busy the past several nights.

Sunday night they were expected to be busy again. However, the forecast is a little more favorable. The National Weather Service has issued a freeze watch with forecast lows in the Orange Belt between 26 and 31 degrees.

Duration of cold temperatures is the critical factor. The duration of time at temperatures in the mid- to upper-20s Saturday was longer than previous cold nights, but with protection by wind machines and water, minimal damage is anticipated. Although some cold pockets dropped down to approximately 25 degrees in the early morning hours, the duration of time at the lowest of temperatures was not significant enough to be a cause of worry.

Growers have been running water over the past few days in order to keep ground temperatures up. Once again, wind machines were turned on between midnight and 2 a.m. for navels as temperatures began falling to the 28 degree threshold in order to keep warm air from escaping the grove.

Fruit on the exterior perimeter of groves, farthest from the wind machines, are expected to incur some damage. But, with moderate temperatures season-to-date, the navel and lemon crops have had time to mature and build up internal tolerance to cold temperatures.

The mandarin crop, however, will likely see some damage resulting from the cold temperatures this weekend. With a threshold of 31 degrees, wind machines have been used for longer durations on mandarins in order to keep damage at a minimum.

Four days into what is forecast to be a five-day frost event, growers in the San Joaquin Valley have spent $11.4 million in frost protection mechanisms, not including previous cold nights this season. At this point of the season last year, the industry had spent approximately $100 million in frost protection.

Sunday may have been the last night to need protection as temperatures are expected to rise into the mid- to upper-30s. Daytime highs will reach 60 by late this week.

Citrus is a three-quarters of a billion dollar commodity in Tulare County, with navel oranges the bulk of what is harvested. To date, only about 25 percent of the crop has been harvested.