Brrrr, it’s cold outside! We’ve been ringing in the New Year with record temperatures all over the U.S. and ironically, the Sunshine State. With recent snowfall reported in the Florida panhandle, Hard Freeze Warnings have prompted swift responses within the agricultural community. According to the National Weather Service, Hard Freeze Warnings state that temperatures 27 degrees or less are expected for at least a period of 2 hours. Considering the severity of these warnings, proactive caution by strawberry farmers is important as Plant City and surrounding farms are responsible for nearly 300 million pounds of strawberries each year.
As noted by John Sizemore, owner of Sizemore Farms and an IMPAC certified grower, “We haven’t seen freezes like this in years, and we have to do what we can to protect our crops during these freezing nights.” Sizemore Farms and many other growers are taking the necessary steps to ensure the safety of our crops.
A strawberry plant can become damaged easily, so growers have to implement creative solutions to ensure high-quality fruit. While it may seem counter-intuitive, it’s very common to see farmers run irrigation throughout the night to create a layer of ice over the entire surface area of the plant. A phenomenon called “latent heat”, the act of creating an ice made shell around the circumference of the fruit is an energy heavy process with a chemical by-product being heat. The act of freezing the fruit is actually an indirect form of insulation. The act of creating the ice actually raises the internal temperature to 32˚F, a “magic number” of sorts. The strawberry plants will avoid any internal damage, so the temperature does not drop below 28˚F for a long period. “Our lowest temperature was 28˚, before that 24,” says Andy McDonald, owner of Sweet Life Farms in Plant City. “It’s more about the duration. One night we ran the sprinklers from 2:30 a.m. – 9:30 a.m., and then another night from 11:30 p.m. – 10 a.m. We are exhausted right now, but we have to do it.”
Although the standard practice is to apply sprinkler irrigation across the field, there are other methods that growers can use to protect their crop when overhead sprinkler irrigation is unavailable. Some growers choose lightweight row covers made from polyethylene, polypropylene, polyester, and other materials (see photo). These row covers work by enclosing the mass of air around the plant canopies and trapping the heat already absorbed by the soil and plant during the day. A labor intensive process, these row covers are placed in the field only during freeze nights and must be removed the following day if the temperature does not threaten to remain low for subsequent freezes.
A third option is the application of foliar polymer to the plants (i.e. Desikote) to reduce or prevent freezing damage. This product is an anti-transpirant that creates a physical barrier and reduces heat loss from plant tissues.
The good news is that our strawberries are still thriving here in Florida thanks to our farmers who determine the best methods for their crops. Look for your IMPAC-grown strawberries in your local stores during Florida strawberry season, Thanksgiving through Easter.