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Stupid Sunshine

February 6, 2009

I am very vocal and passionate about my hatred for the cold. I know I’m not going to get much sympathy from the rest of the country but I feel completely justified complaining that it felt like 17 degrees this morning walking into our lovely Mayo building.

For Florida farmers the cold isn’t an inconvenience, it can mean the loss of hundreds, thousands or even millions of dollars worth of production. This week’s unusually cold temperatures had our entire industry on alert.

Farmers usually know for several days in advance that temperatures are going to reach a critical point. To protect vulnerable crops, farmers exploit some simple concepts to keep plants warm and minimize freeze damage. One of the most visually impressive (see below) is spraying crops with water to create a protective layer of ice.

A big thank you to Cindy Suszko, Sr. Market Manager of the Plant City Farmers’ Market, for the great photos!Young citrus trees

freeze2

Strawberries covered with ice

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5 Comments leave one →
  1. Zach permalink
    February 9, 2009 4:08 pm

    That’s crazy to think the farmers intentionally spray water on their crops to keep them from freezing. Doesn’t that go against everything our parents taught us when were kids! Or now you know my parents are not in the agriculture business. I wouldn’t believe this is the answer to keep our produce from freezing without the pictures.

  2. paul permalink
    February 10, 2009 11:28 am

    I’m not a scientist, but I’ll play one on this blog.

    The way it was described to me is that frozen water (the Indians call it ice) is 32 degrees Fahrenheit. Not 31, surely not below 28 as some of our citrus areas incurred.

    That being true, a barrier of ice around the plant and it’s fruit prevents those 28 degree temps from reaching the plant causing more harm than if left exposed.

    Any further insight would be appreciated!

    pd

  3. erin permalink
    February 10, 2009 1:57 pm

    Actually, the principle behind using irrigation to protect against frost/freeze (there is a difference b/w the 2) is the latent heat of fusion and not the igloo principle that you described. In not-so-scientific terms, heat is released when water changes to ice. When a farmer turns on irrigation during freezing temperatures, the water freezes on the crop, releasing heat. This heat replaces the heat crops lose to the environment when it’s cold. Because heat is only released when water turns to ice, farmers must irrigate continuously and consistently until temperatures rise enough to melt the ice.
    If you don’t believe me or need a more detailed scientific explanation, go to http://www.ces.ncsu.edu/depts/hort/hil/pdf/hil-705.pdf.

  4. Chilly Willy permalink
    February 12, 2009 12:21 pm

    Nice tie-in to latent heat of fusion. Tell that to the ice fishermen on Lake Erie. “Just keep going back in. It works in Florida! “

  5. Dan permalink
    February 20, 2009 9:33 am

    Besides of course the heat fusion process, which is interesting and widely in use, industry may also opt to utilize the disruption of thermoclimate…that is, the air is coldest near the ground and slightly warmer at say 6 to 25 feet (no lapse rate effect)…in dire conditions many will use helicopters to push warmer air down upon trees and plants–it’s expensive though, running around $1000 an hour for a bird–but if you can save for instance 20 acres of strawberries–which produces 2200 flats per acre at approximately $16.00 per flat, well, your $700,000 crop might still be marketed. And farmers are smart enough to use every tool is the tool box when it comes to safeguarding their livelihoods.

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