Temperatures throughout most of the Central Valley citrus belt failed to reach predicted lows Thursday night and Friday morning. In the coldest of areas, temperatures dipped to 26 degrees, although for much shorter durations than originally anticipated. Generally, temperatures hovered in the 29 to 31 degree range for most of the night and early morning.
Growers report turning on wind machines to keep grove temperatures elevated by as much as 3 degrees to ward off any potential for freeze damage. Growers also report running water in the groves yesterday to moisten the ground in anticipation of the cooler temperatures. As the warm air rises from the moist ground, wind machines effectively trap and circulate warm air in the grove. When temperatures fall below critical levels, even a two-degree increase can prevent crop losses.
For the navel orange crop, growers ran wind machines for an average of 6 to 8 hours overnight. For the less cold-tolerant Mandarin varieties, growers report using wind machines for an average of 10 hours. The duration of cold temperatures is a critical factor in whether a freeze event is positive or negative. In the case of last night, temperatures were cooler than the previous night, but with protection, were well within a manageable range and no freeze damage is expected.
The average cost to run a wind machine is $22 per hour and each wind machine can protect up to 10 acres. Season to-date, growers have collectively spent an estimated $23 million to protect the Valley’s citrus crop. Valued at over $2.6 billion, the Central Valley accounts for nearly 80 percent of the State’s total citrus production.
The citrus crop is currently 25-30% harvested and the season is anticipated to go through mid-June. At this point in the season, cold weather is to be expected and is beneficial for fruit quality, color, and flavor. The gradual reduction in temperatures, and the mild winter conditions season to-date has also helped to “harden off” the trees so that if, or when, a freeze episode occurs the trees will be stronger and less prone to fruit drop.
For the time being, it appears Mother Nature has delivered an early Christmas present for Valley citrus growers.