Chill Threatens Florida's Valuable Winter Crops

A layer of ice might not seem the best way to protect a plant from freezing temperatures, but some of Florida's farmers are doing everything they can think of to protect their valuable winter crops from the increasing cold.

CBS News correspondent Mark Strassmann reports that some citrus farmers in Clermont, Fla, actually spray water over their crops when the temperature drops because ice acts like a blanket from even colder temperatures.

Florida's annual citrus crop is worth billions of dollars annually, and many farmers were thankful that temperatures did not stay below 28 degrees, the threshold below which crops die.

Near St. Petersburg, some farmers hired helicopters to hover about their vegetable crops to push warmer air closer to the ground.

Farmers are especially nervous because an 11-day freeze in January wiped out many crops, from corn to kumquats. Florida is the largest winter producer of sweet corn in the U.S. - the kind people eat. In 2009, the value of production of sweet corn from Florida was $227 million.

The helicopters, which can cost as much as $2,500 per hour, work because the air 50 feet above the crops is warmer than the air near the plants. The helicopter blades push the warm air down and the temperature goes up, said David Sui, a University of Florida expert on vegetables and tropical fruits. The warmer air prevents cold and frost from settling on the plants.

"Even if it raises the temperature a couple of degrees it may save the crops," he said.

Last week, three helicopters crashed within a matter of hours in South Florida during missions to protect crops from the cold. All three pilots survived.

Green beans and sweet corn are cultivated in the nutrient-rich muck soil located near the Florida Everglades, though farmers in other parts of the state are also scrambling to protect their fruits and vegetables, many of which are near harvest.

When Florida's crops die, shoppers pay more at the grocery store because replacement produce is usually imported from outside the U.S.

Gov. Charlie Crist on Sunday declared a state of emergency because of the threat of severe crop damage. That news prompted orange juice futures to rise over concerns the weather would damage this year's crop.

It's unusual for temperatures to be this cold this early in the season, said Lisa Lochridge, a spokeswoman for the Florida Fruit and Vegetable Association.

Temperatures are expected to dip below freezing in central and South Florida - though temperatures of up to 78 degrees are more common this time of year.

"When you're talking about temperatures as cold as those predicted, virtually everything is in peril," she said.