Citrus growers in the San Joaquin Valley were prepared last night for subfreezing temperatures which fell to predicted lows within the citrus producing areas of Kern, Tulare, and Fresno counties.
Growers starting running water as early as last weekend to saturate the ground in preparation for this cold snap, which is expected to continue through Saturday morning. In most areas warmer ground temperatures added extra crop protection, allowing wind machines to create an inversion layer and raise grove temperatures above critical levels.
The mandarin crop can withstand temperatures as low as 32 degrees, which materialized in many areas as early as 6 p.m. last night. Tuesday night was the first night of the season frost protection was necessary for the mandarin crop. Between Tuesday night and Wednesday night, wind machines have run approximately 27 hours for mandarins.
The more frost tolerant navel crop can withstand temperatures as low as 27 degrees before any damage is incurred. All field reports indicate that frost protection was successful in most areas at keeping grove temperatures above that critical point throughout the night. However, temperatures did fall considerably for a short duration at 6 a.m. this morning. Wind machines for navels were turned on last night at about 11:00 p.m. and ran for duration of 12 hours.
California Citrus Mutual estimates the total cost of protection at approximately $6.7 million for the navel and mandarin crops.
In some isolated cold spots temperatures fell to the low 20s, in which cases fruit damage is expected. However, the extent of the damage will not be known for about 3-4 weeks. It is anticipated that the mandarin crop will sustain the most damage, particularly in the coldest areas along border rows where wind machines and water protection are less effective.
At this point of the season, approximately 15% of the Valley's navel orange crop and 20-25% of the mandarin crop has been harvested. Field reports show that the fruit is maturing nicely with a high sugar content, which will offer some internal protection for the fruit through the remainder of the cold season.