It appears likely the California dry-bean industry can continue some use of methyl bromide to control insect pests during storage, although the amount of the fumigant to be available remains uncertain, says an industry leader.

The widely-used fumigant, identified as an ozone-depleting substance, is scheduled for phasing-out in developed nations by 2005 under the Montreal Protocol, the landmark international agreement designed to protect the stratospheric ozone layer.

Exemptions, however, are allowed for quarantine purposes or critical uses by developed nations where no alternative is available. Economically emerging nations are allowed declining amounts of use under a phase-out to be completed in 2015.

In a recent report to members of the dry-bean industry and others gathered at Bakersfield, Paul Paulin, manager of the Cal Bean and Grain Warehouse at Pixley, said the industry has no suitable alternative.

Applications for critical-use exemptions submitted by his cooperative and some 50 other organizations across the nation, including the California Bean Shippers Association, have been cleared by U.S. State Department officials for submission to the protocol organization of 160 nations.

The applications were scheduled to be taken up at a meeting of the protocol in Nairobi in November of 2003 to define the amount of methyl bromide available to the dry-bean industry. Consideration was postponed, however, until a meeting set for March of this year in Montreal.

Exemption reasons

Paulin said the protocol allows for two reasons for exemption among developed nations. One is when the specific use is critical because the lack of methyl bromide would create significant market disruption. The other is when there is a lack of technical or economically feasible alternatives acceptable on the basis of environmental and health concerns.

“So we have two different ways to state our case and we've done well to this point,” said Paulin, a member of the California Dry Bean Advisory Board.

“But the problem now with these international meetings is they are starting to politicize decisions and not make them on the basis of scientific review called for in the Montreal Protocol.”

The major issue in the exemptions will be what cap or maximum percentage of methyl bromide will be allowed, based on the 25,000 metric tons used in the U.S. in 1991. Paulin said no percentage was set by the treaty, and now environmental interests are challenging the 39 percent cap proposed by the dry-bean industry. He added that he believes some sort of limit on exemption use will be eventually applied.

“Even without taking into account the costs of using methyl bromide in handling, especially for adequate pest control during a brief bean harvest season, there is no good alternative for us.”

He went on to explain that his industry has no material that comes close to the 12 hours that methyl bromide fumigation needs for full effect against all life stages of economic pests such as cowpea weevil and bean weevil before dry beans go into storage. Other chemicals require more time to be effective.

Longer times require more fumigation chamber space to handle the same volume of beans. Costs of providing more space, he noted, would crimp resources of handlers, who would have to recover costs from already strapped growers.

Phostoxin gas

One alternative, Phostoxin gas injected into a chamber, requires a minimum of 48 hours to kill weevils and as much as 72 hours when used during cold winter months.

Even though researchers attempt to find ways to reduce the time needed, he added, “There's not a lot of good evidence that we get as good a kill from this gas as from methyl bromide.”

Use of Phostoxin in tablet form falls short because of the residue left after a fumigation. “It's a worker-exposure issue to deal with these. Methyl bromide, on the other hand, is injected from outside the fumigation chamber without exposing workers,” he said.

Eco-fume, another fumigant used for dry beans, has been proposed as an alternative, but Paulin said its costs and longevity following shipment and a couple of months of storage are unknown. It too requires at least 72 hours for effectiveness during cold, wet weather.

Methyl iodide has been suggested as an alternative to methyl bromide for some uses, yet Paulin rejected it because of its high cost and the reluctance of U.S. manufacturers to add it to their product lines.

Legislation spearheaded by Congressman George Radanovich, R-Mariposa, seeks a solution by placing decisions on critical-use exemptions with U.S. agencies and not the Montreal Protocol.

“Our government,” Paulin concluded, “has realized there's a problem with the protocol and they can't phase out methyl bromide because several of us need it so badly. I'm starting to feel like we are going to get it one way or another. It just may be in limited quantities, but we'll have a lot more time to find an alternative.”