By Chris Oswalt
The weather folks are predicting weak to moderate La Niña conditions this winter. Typically, having either the La Niña or El Niño conditions during the winter in Florida is a good thing. There is a historically lower probability of having severe freezing temperatures during either of these El Niño-Southern Oscillation (ENSO) conditions in Florida.
What this means for Florida specifically is warmer winter temperatures and less rainfall. While freezes can occur any time during the winter, chances are greater during near neutral ENSO winters. Notice I said “greater,” which should not imply “nonexistent” during any given ENSO winter condition in Florida.
Regardless of the ENSO conditions, growers should have a citrus cold production plan in place. This plan should take into consideration practices to implement now before a freeze. It should also include a cold-protection action plan to execute during the immediate days prior to and during a freeze event.
Before a freeze event is even forecast, growers using micro-sprinkler irrigation systems for cold protection should ensure that the systems are properly maintained and operational for use. In addition, now is the time for growers to manage their tree row middles by cleaning them up or mowing. This will enhance the soil absorption of solar energy and the natural flow of cold air out of the grove. Ensure fuel-burning engines and pumping systems to run micro-sprinkler irrigation systems are well-maintained and operating properly. Make sure to have enough fuel for multiple days in case of a major freeze event.
At the time of the freeze, growers need to know the threshold temperature or critical temperature at which they would want to protect their trees. Usually this will depend on the type of freeze and the characteristics of the cold air mass. This type of information should come from a reliable weather forecast source, such as the Florida Automated Weather Network website. Once the freeze event begins, know the temperature and wind parameters which must be met for you to turn your micro-sprinkler irrigation system on and off.
More detailed information on the cold protection of Florida citrus can be found in the 2021-22 Florida Citrus Protection Guide’s chapter on citrus cold protection.
Chris Oswalt is a UF/IFAS citrus Extension agent for Polk and Hillsborough counties.
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