Methyl bromide is a chemical fumigant used to sterilize the soil for field crops like strawberries and to kill pests on export crops like walnuts and almonds.
Nov. 6— Methyl bromide is a chemical fumigant used to sterilize the soil for field crops like strawberries and to kill pests on export crops like walnuts and almonds.
It has also been identified as a contributor to ozone depletion in the atmosphere, so an international group of more than 180 countries called the Montreal Protocol is trying to ban its use around the world.
Facing a January 2005 deadline to phase out the chemical, state, federal and international agencies are continuing to sort out rules for getting rid of it — and who can use it after the deadline.
But the phaseout is already reducing the use of methyl bromide.
In Stanislaus County, for instance, growers used 243,620 pounds of methyl bromide in 2000. By 2002, the most recent statistics available from the Department of Pesticide Regulation, the county used 72,983 pounds — a 70 percent reduction.
However, developed countries are allowed exemptions for agricultural uses in which a suitable alternative can't be found. Less-developed countries also have longer to phase out the chemical.
One of the exemptions allowing continued use of methyl bromide in the Central Valley is for sterilizing commodities for export.
"There's really no viable alternative, from a time standpoint and cost-effectiveness," said Steve Slacks, vice president of Frazier Nut Farms in Waterford.
Frazier pumps methyl bromide into a vacuum chamber full of walnuts, then uses air to clean the fumigant off the nuts, Slacks said.
The process takes about four hours, compared with three to seven days for an alternative chemical fumigant, Slacks said.
Some methyl bromide does get into the atmosphere, he said, but new fumigation chambers are now required to have air scrubbers to burn off any chemical residue before it is released.
The chamber is inspected annually and certified by either the county or state, Slacks said.
Another obstacle to switching to an alternative chemical is that some countries specifically require imported walnuts to be treated with methyl bromide, Slacks said.
Without the treatment, that export business would be lost, he said.
Rodger Wasson, president of the California Strawberry Commission, also sees problems with the phaseout.
Strawberry growers cover fields with plastic and inject methyl bromide into the soil to combat pests that attack the roots of the plants.
Strawberries are allowed to use 3.2 million pounds of methyl bromide next year, down from 3.7 million pounds in recent years, Wasson said. An additional 20 percent reduction has been recommended for 2006, he said.
About a third of California's strawberry acreage is using alternative chemicals, but not everyone can, Wasson said.
Factors such as the slope of the land and soil conditions can make alternatives more or less effective, he said. Growers will have a learning curve to find the best methods for applying new chemicals, he said.
The strawberry industry also has competitive issues with the phaseout, Wasson said. China, as a developing country, has 10 more years to stop using methyl bromide — and is exporting frozen strawberries to the United States.
"The concern is that they don't have to go by the same rules we do," Wasson said.
California's Department of Pesticide Regulation approved new regulations for methyl bromide last week which are focused on limiting the amount of the chemical that gets into the air, rather than the amount used.
The state regulations, unrelated to the federal and international efforts to ban methyl bromide, make more sense, Wasson said.
Strategies such as drip application of methyl bromide can reduce the amount that gets into the atmosphere, he said.
Not everyone is happy with the exemption process.
David Doniger of the Natural Resources Defense Council contends that the United States is asking for exemptions in 2005 that would exceed the total use of methyl bromide in 2003.
"I'm not saying there are no critical uses, but we don't want to go backwards," Doniger said. "The numbers requested are drastically excessive.
Somewhere closer to zero is where the exemption should be," he said.
The U.S. Environmental Protection Agency says the 2005 exemption is for 35 percent of the 1991 use, a figure it called "robust."
Wasson commented that farmers won't use more than they have to, given the phaseout.
"If they find an alternative is working well, growers will switch," he said.
"Just because it is being requested doesn't mean it will be used."
Doniger is skeptical. People don't like change, he said, and will stay with something they are familiar with unless cost or regulation forces them into alternatives.
In the meantime, researchers and growers are working on pest treatment alternatives, and the EPA is evaluating them.
AT A GLANCE:
—Methyl bromide is an effective fumigant used to control insects, nematodes, weeds and pathogens in more than 100 crops.
—Besides agricultural applications, it also is used in forest and ornamental nurseries and in wood products.
—Primary ag uses include soil fumigation, post-harvest protection and quarantine treatments.
—The United States uses about 60 million pounds of methyl bromide each year.
—Of that amount, about 75 percent is to fumigate soil before planting crops, about 11 percent to fumigate harvested crops; and about 6 percent to fumigate structures: food processing plants and warehouses. The remaining 8 percent goes into the production of other chemicals.
—It's even used to fumigate museums and antiques.
—More than $431 million in U.S. exports were treated with methyl bromide in 1994 (the latest year for which figures are available).—Required by the importing countries, the fumigated crops include apples and cherries going to Japan, cotton and peaches to Mexico, oak logs to Europe and strawberries to Australia.
—The fumigant also is used extensively at ports of entry on commodities found to be infested with exotic pests that might pose a threat to U.S. agriculture.
Sources: Agricultural Research Service, U.S. Department of Agriculture
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