Farmers who plant varieties containing Monsanto's new Roundup Ready Flex technology won't be limited to early season over-the-top sprays as they have been with the first generation of Roundup Ready.

But Monsanto will stress that growers should continue to try to control weeds as early as possible in their Roundup Ready Flex cotton although those varieties will have a wider application window for Roundup herbicide.

“We know that cotton is very sensitive to early season weed competition when growing conditions are less than ideal,” said Kent Croon, product manager for Monsanto's Roundup Ready Flex technology, which recently received regulatory clearance from USDA and the U.S. Food and Drug Administration.

“We will continue to recommend that farmers spray early — when weeds are in the one- to two-leaf stage when possible — to reduce that competition and control those weeds when they are generally more susceptible to herbicides.”

The clearances by USDA and FDA moved the Roundup Ready Flex technology a step closer toward its anticipated commercial launch for the 2006 growing season. Monsanto said in a press statement that regulatory clearances in other key production and export countries are expected later this year.

Varieties containing the Roundup Ready Flex technology will have tolerance to Roundup Ready herbicide during both the vegetative and reproductive stages of plant development. The older first generation Roundup Ready varieties had full tolerance to Roundup in the vegetative stage and limited tolerance in the reproductive stage.

As a result of the increased tolerance, Roundup Ready Flex varieties can be sprayed over the top with Roundup through layby and beyond, according to Croon.

“The new technology has novel promoter sequences that drive the expression of the gene that conveys tolerance,” he said. “It's the new promoter system that gives us tolerance in the vegetative and reproductive stages.”

Croon said Monsanto began developing the Roundup Ready Flex technology in 1998, the year after it introduced Roundup Ready cotton in the United States.

“Roundup Ready cotton gave us a number of benefits, including a broad spectrum weed control system, increased rotational options, reduced labor costs, increased grower profitability and broad compatibility with reduced tillage and IPM practices,” he said.

“But growers also told us they would like to have greater flexibility in making herbicide applications. Roundup Ready Flex cotton was developed to provide growers that greater flexibility.”

Taking another cue from growers, Monsanto also began providing seed from varieties containing the new technology to university scientists in 2001. Since then, three-fourths of the tests involving Roundup Ready Flex cotton have been conducted by university and third party researchers.

“We feel that you really can't get the technology out to universities soon enough,” said Croon. “We want them to be able to get a good look at the new varieties before they're in growers' hands.”

Although growers will no longer be required to precision post-direct Roundup at fifth leaf through layby once Roundup Ready Flex varieties are fully cleared, Croon said post-directed spaying may still have a place in the new system.

“Our recommendations will say post-directing should be used ‘as needed to achieve weed coverage,’” he noted. “There may be times when growers still need to spray near the base of the plant to control certain weeds.”

Croon said Monsanto will continue to broadly license the Roundup Ready Flex cotton trait to seed companies. Elite varieties from those companies, including Roundup Ready Flex and Bollgard II stacked gene versions, are expected to be available for the 2006 season.

Monsanto officials said the regulatory actions for Roundup Ready Flex cotton affirmed the benefits transgenic lines of cotton and other crops have provided to farmers.

“These clearances by USDA and FDA underscore the food, feed and environmental safety of this and other plant biotechnology products which have delivered tremendous value to growers and the environment over the last 10 years,” said Robb Fraley, Monsanto's chief technology officer.

No restrictions on domestic planting or food and feed use of Roundup Ready Flex cottonseed exist now that the USDA and FDA have completed their review processes, he said.