SoCal fires impacting citrus industry

The cold overnight lows this week are just what Central Valley citrus growers needed this time of the year.

Freeze alerts were issued for the region earlier this week with some forecasters projecting lows to be in the high 20s, but fortunately for citrus growers the critical temperatures were not felt.

In the Central Valley, sub-freezing temperatures failed to materialize as forecast last night, dipping only into the low 30s in the early morning hours.

“Generally, last night’s temperature conditions were ideal for the area’s citrus crop, ” California Citrus Mutual of Exeter stated Tuesday. “Central Valley citrus growers report conditions were ideal for crop at this point in the season given the mild conditions to-date.”

Those mild conditions have kept the navel orange harvest in Kern and Tulare counties from shifting into high gear.

Approximately 85-90 percent of the Central Valley navel orange, lemon, and Mandarin crops remains on the tree, CCM stated. At this point in the season, a gradual decrease in temperatures, rather than a sudden drop, will better enable a tree to adjust while promoting a steady maturation process of the fruit by improving color and increasing flavor.   

With temperatures hovering around the freezing mark, growers were still busy protecting their crop. Monday and Tuesday night were expected to see the coldest overnight lows. Wednesday and Thursday night were forecasted to be in the 28-34 degrees range with daytime highs in the mid to upper 50s to around 60. No rain is in the forecast for the next week.

Navel and lemon crops growers report sporadic and limited use of wind machines for frost protection. For these more cold-tolerant varieties, critical temperatures at which frost protection is needed is generally 27 degrees and below, CCM stated.

“Duration of cold temperatures is a critical factor in whether a freeze event is positive or negative,” according to CCM. “In the case of last night, temperatures did not approach critical levels, and were in fact a very welcomed change from the unseasonably warm temperatures had to-date.”

Some growers did report running water as a precautionary step to keep the ground moist and grove temperatures elevated slightly. In the event of a hard freeze, the combination of a wet orchard floor and the use of wind machines can elevate temperatures in the grove by as much as 5 degrees.

“As the warm air rises from the moist ground, wind machines effectively trap and circulate warm air in the grove,” CCM stated. “When temperatures fall below critical levels, 5 degrees is significant in preventing crop losses.”

For the less cold-tolerant Mandarin varieties, growers report using wind machines for an average of 10 hours last night in combination with running water.  The critical temperature for mandarins is generally 32 degrees, however, growers will run wind machines at warmer temperatures early in the season to allow the trees to adjust.

While Central Valley growers evaded Mother Nature last night, Citrus Mutual reported the widespread wildfires in Ventura County appear to have impacted the local citrus industry, although the extent is unknown at this time. Reports indicate the area between Santa Paula and Ventura — a large citrus producing area in the region — was most significantly impacted.

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