WASHINGTON - U.S. farmers who grow tomatoes and strawberries might have to cut back more than they planned on the use of an ozone-depleting pesticide.

Negotiators for an international treaty to phase out chemicals that harm the Earth's protective ozone layer are balking at the continued delay the United States sought in meeting the 1987 treaty's goal for a 2005 ban on methyl bromide.

The situation adds uncertainty for U.S. farmers' plans for the planting seasons and crop income. The chemical also helps control pests in wooden pallets used by shippers.

The treaty allows for "critical use" exemptions, and the Bush administration has asked for one for a second year in a row. This time it wants to use the popular killer of insects, weeds and diseases at a rate of 37 percent, or 5,550 tons, of the 15,000 tons used in 1991.

Other nations want the U.S. request scaled back to 27 percent, or 4,050 tons.

"All the parties want to get to zero but we're obviously not quite ready to do that yet," Claudia McMurray, deputy assistant secretary of state for environment, said Tuesday by telephone from Prague, Czech Republic, where negotiations were being held this week.

Last year, the United States won an exemption at a rate of 35 percent of its 1991 baseline. Among all nations, the United States was using nearly two-fifths of the 38,600 tons of the pesticide used worldwide in 1991. Others nations also have requested exemptions.

"We've already come way down in our methyl bromide use," McMurray said. Government figures put U.S. consumption at 6,300 tons in 2002.

The Natural Resources Defense Council, an environmental group, says the administration is promoting "industry-friendly increases" in the chemical's use. But McMurray denied the administration was catering to industry.

Some 183 countries, including the United States, signed the United Nations' 1987 Montreal Protocol on Substances that Deplete the Ozone Layer.

Source: Associated Press