Here Comes The Sun

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Here Comes The Sun

Sunshine helps plants grow, and it can help rid soil of harmful organisms that hurt Florida’s crops, a University of Florida expert says. In a process called soil solarization, farmers prepare planting beds by covering them with clear plastic sheets for several weeks during the summer, trapping heat that destroys weeds, nematodes, and fungi. Popular in California and Israel, solarization is well-suited to Florida’s climate, though the practice is seldom used here, says Bob McSorley, a nematology professor with UF/IFAS.

A study published in the September 2009 issue of the International Journal of Pest Management showed solarization effectively prepared planting beds for snapdragons, in some cases as well as the soil fumigant methyl bromide.

“The big challenge is getting growers to adopt it,” says McSorley, an author of the study. “They never thought of doing without soil fumigants.”

Seeking Alternatives

Soil fumigants are chemicals sprayed or injected into soil to kill pests and pathogens before planting. The best known is methyl bromide, which is being phased out. Federal law now restricts methyl bromide use nationwide; in Florida’s it’s allowed for a handful of crops including eggplant, pepper, strawberry, tomato, cut flowers, and ornamentals. Growers and researchers want cost-effective alternatives.

Solarization has some advantages over fumigants, McSorley says. It’s inexpensive, and it’s environmentally friendly, though the sheeting requires disposal.

The downside is, solarization requires intense sun exposure, so it can only be used during summer to prepare beds and fields for fall-grown crops. And three to four months after solarization, harmful organisms start to return. “There are some limitations to it,” he adds. “If you want a spring crop, you have to use another method in the winter time.”

Testing Grounds

McSorley recommends interested growers try solarization on a small plot and see if it gives the results they need.
One farm that’s taken that first step is Sunshine State Carnations. Last year, the operation, which has locations in Palm City and Hobe Sound, took part in a USDA study. It was successful, and this year both locations are using solarization on half-acre plots, says USDA plant pathologist Dan Chellemi.

The study is meant to demonstrate that solarization is practical on a commercial scale, says Chellemi, who is based at the USDA research laboratory in Ft. Pierce. Overall, he says, solarization has “tremendous potential” for Florida vegetable and floriculture farms, especially when the method is used as part of an integrated pest management approach.

For more information, see “Solari-zation for Pest Management in Florida,” http://edis.ifas.ufl.edu/IN824.

Tom Nordlie is a science write for UF/IFAS in Gainesville, FL.

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