Beating The Ban: UF Researchers Seek Alternatives To Methyl Bromide

Joe Noling (941) 956-1151
John Van Sickle (352) 392-1826 ext. 221
Michael Stuart (407) 894-1351
Jessica Vallette (202) 783-7400

GAINESVILLE—Methyl bromide, a soil fumigant used to control soilborne pests, is the single most important pest management tool used to produce high-value crops in Florida today, but it’s blamed for contributing to the depletion of the earth’s protective ozone layer.

A recent delay in the 2001 ban on this pesticide until 2005 is giving University of Florida researchers more time to develop effective alternatives.

“Now that Congress has delayed a looming ban on methyl bromide until 2005, we’re intensifying our search for alternatives to the ozone-depleting pesticide,” said Joe Noling, who heads a statewide research team for the UF’s Institute of Food and Agricultural Sciences.

He said the delay brings the United States in line with other developed countries that must stop using the broad-spectrum soil fumigant by the year 2005. However, under the Clean Air Act of 1990 and the ozone-protection treaty known as the Montreal Protocol, developing countries such as Mexico can continue using methyl bromide until 2015.

“Giving Mexico, our strongest competitor in the winter vegetable market, another 10 years of use will put Florida producers at a real competitive disadvantage — unless we can develop cost- effective alternatives,” said John Van Sickle, a UF agricultural economist. “Methyl bromide is our single most important pest management tool, and it’s critical to farming in Florida and California.”

Van Sickle, who serves on the United Nations’ Economic Options Committee that evaluates ozone-depleting substances, said there currently is no suitable alternative to methyl bromide. The soil fumigant is essential in the production of tomatoes, strawberries, bell peppers, eggplant, cucumber, squash, watermelon, ornamentals and turf. It’s also widely used to fumigate citrus and other produce entering and leaving the United States.

Ending use of methyl bromide would leave producers without an effective control for nematodes, diseases and weeds, resulting in an estimated $600 million loss in Florida fruit and vegetable production and jeopardizing some 13,000 jobs, said Michael Stuart, president of the Florida Fruit and Vegetable Association in Orlando.

Meanwhile, environmentalists want an immediate ban on methyl bromide. Jessica Vallette, atmosphere campaigner at Friends of the Earth in Washington, D.C., said the United States uses 40 percent of all methyl bromide in the world, and developing countries use only 18 percent.

“There already is significant ozone depletion over the Northern and Southern hemispheres, and it makes no sense to delay the ban any longer,” Vallette said. “Ozone depletion increases the amount of harmful ultraviolet radiation that causes skin cancer, cataracts and weakened immune systems. It also poses a risk to farm workers and residents near fields where the pesticide is applied.”

Joe Noling, associate professor of nematology based at UF’s Citrus Research and Education Center in Lake Alfred, has coordinated UF research efforts on alternatives to methyl bromide since 1993 and says that alternatives identified to date all have shortcomings of one kind or another. These include loss of pest and disease control or yield inconsistences, or requirements for additional land, equipment, or worker protection and safety equipment.

“We’ve tested both chemical and nonchemical alternatives, and the results from this work show there is no one chemical or nonchemical treatment that will do as effective a job as methyl bromide,” he said. “However, tests on a so-called chemical cocktail approach, a combination of three separate chemicals, have produced some encouraging results on tomatoes.”

The cocktail is a combination of three different chemicals (1,3-dichloropropene and chloropicrin; Telone C-17 or C-35) and a separate, but complementary, herbicide treatment (such as Tillam).

Noling said lower crop yields, coupled with higher application and labor costs, have not always been acceptable for growers who have tried the cocktail treatment. Of particular concern to all growers is that one of the chemicals in the cocktail, Telone, requires all workers in the field at the time of application to wear uncomfortable protective gear and respirators during hot weather.

“If alternative application methods cannot be developed and implemented, then these requirements will — in all probability — force growers to limit field workers to no more than 20 minutes work per hour, according to current Occupational Safety and Health Administration standards,” he said. “You don’t have to be a rocket scientist to see how labor requirements would increase dramatically, which would probably limit the broad scale adoption of such a tactic.”

Noling is working with a team of UF researchers who also are evaluating various chemical and non-chemical pest management tactics, including biological control agents and derivatives of natural products, organic amendments, cover crops, plant resistance, flooding and soil solarization (use of clear plastic to trap solar radiation in beds and kill pests, diseases and weeds).