The Environmental Protection Agency has completed its Food Quality Protection Act-mandated reassessment of the cotton defoliant tribufos (DEF and Folex) and agreed that cotton producers may continue to use the product.

Because it is an organophosphate compound, tribufos was subjected to a lengthy reassessment process that took more than 18 months. EPA has negotiated agreements restricting uses and resulting in voluntary cancellations of some uses of other organophosphate materials.

"This has been an interesting process in that EPA initially sought a voluntary cancellation of tribufos, and today's decision ended with a re-registration decision that is agreeable and favorable to cotton production," said Keith Menchey, manager of science and environmental issues for the National Cotton Council.

Menchey and producer representatives of the council worked closely with EPA and Bayer Corp., the major registrant of tribufos, during the reassessment process for the compound.

Those efforts included a tour of cotton operations in the Phoenix, Ariz., area for four EPA staff members last November to discuss and demonstrate the importance of tribufos and defoliation and to provide the staff members the opportunity to observe cotton harvesting and ginning operations.

The Cotton Council also scheduled a meeting between EPA and Allen Helms Jr., then chairman of the American Cotton Producers; Mark Williams, an NCC producer director from the Texas High Plains; and Roger Isom of the California Cotton Growers Association.

"Tribufos is critical to cotton production in the U.S.," said Helms, a producer from Clarkedale, Ark. "We told EPA about the benefits of DEF, including its ability to work when temperatures drop below 65 degrees. We also pointed out the role that proper defoliation plays in insuring a harvest that captures the highest fiber quality possible."

In its Re-registration Decision Summary, EPA also cited an economic impact analysis from both the Cotton Council and USDA which showed that the loss of tribufos would cost the cotton industry $156 million annually.

Menchey said that late in the tribufos reassessment, EPA proposed a 150-foot aerial application buffer strip from water bodies that support aquatic life.

Council staff members consulted at length with growers across the Cotton Belt who expressed concerns about dealing with the buffer strips. Those concerns were relayed to EPA, which, upon further consideration, decided to retract the buffer zone requirements.

Meanwhile, EPA has proposed mitigation measures because of concerns about exposure risks to workers. Those include application rates of 1.5 pints per acre per year except in Arizona and California where maximum application rates will remain at 2.5 pints per year; increasing the re-entry intervals from 24 hours to seven days; and closed delivery systems. None of the changes will take effect this year.

Menchey said the National Cotton Council would continue to work with EPA on developing the guidelines for implementing those changes.