Freeze Probability and Protection Efforts

Ernie NeffFreeze Protection


Citrus trees coated with ice at the base, due to microirrigation freeze protection

Florida hasn’t had a widespread tree-killing citrus freeze in years. That’s very fortunate since the industry has been dealing with the highly destructive HLB disease since 2005 and with negative impacts of Hurricane Irma since September. However, a damaging freeze is always a possibility at this time of year. Consequently, multi-county citrus Extension agent Chris Oswalt held a winter weather update recently in Bartow. Oswalt, agent for Hillsborough and Polk counties, discussed the probabilities of freezes and the science behind growers’ widespread use of microsprinkler irrigation for cold protection.


chris oswalt

“Right now we’re in what we call a near-neutral (weather) condition,” Oswalt says. “Those near-neutral conditions sometimes are when we have our typical bad freezes.” He reports on a research paper that studied freezes from the 1980s through 2000. The paper stated that during that period, there was a 50 percent chance of a hard freeze during a year with near-neutral conditions. Three hard freezes during the 1980s destroyed a large percentage of Florida’s citrus acreage, but the industry recovered well prior to the discovery of HLB in 2005.

Oswalt addresses microsprinklers for cold protection. He says growers get a “significant benefit” from microsprinkler irrigation use within the canopy of the tree when winds are calm. Temperatures within the canopy can be four degrees warmer than the outside air. Additionally, microsprinkler use reduces the length of time temperatures remain below a critical temperature, he says.

The Extension agent offers a bit of advice for using microsprinklers as cold protection. “Just make sure you’re ready for it,” Oswalt says. “And make sure that you have a plan in place that if you’re going to choose to use microsprinklers for cold protection, make sure you make those decisions early on before you have any problems with your irrigation system freezing up.”

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About the Author

Ernie Neff

Senior Correspondent at Large