From the Exeter-based California Citrus Mutual:
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 mechanisms to be successful at preventing any damage to this season’s citrus crop. Ventura, Riverside, and Imperial leveled out in the 30s, again, manageable temperatures with frost protection.UPDATE 2:30 P.M.: Some citrus damage has been reported, according to the AP via CapitalPress.com.
Duration of cold temperatures is the critical factor. The duration of time at temperatures in the mid to upper 20s 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 32 degrees, wind machines have been used for longer durations on mandarins in order to keep damage at a minimum.
Three days into what is forecast to be a 4-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. Needless to say, this season has been far more moderate than last, and the crop is expected to make is through the cold nights with little damage. The citrus harvest is approximately 25% complete.
Growers are anticipating and preparing for another cold night tonight and will be running water and wind machines starting in the early evening.