The countdown is under way for growers eagerly anticipating herbicide-tolerant alfalfa varieties.

"We're predicting the commercial release of a wide range of Roundup Ready (RR) alfalfa varieties in 2004," says Mark McCaslin, president of Forage Genetics International, West Salem, WI.

There's significant interest in the use of RR alfalfa to improve weed control options, both for establishment and for the control of tough perennial weeds in established stands, says Dan Undersander, University of Wisconsin extension forage specialist. Once approved, the genetically engineered varieties will allow growers to apply Roundup Ultra herbicide to control broadleaf weeds and grasses.

"I think Roundup Ready alfalfa will be readily accepted in the commercial hay-making regions that have a history of herbicide use and receive a premium for clean alfalfa fields," says Undersander. "I also predict it'll be of great value in the Southeast to control winter annual weeds.

"There may be less acceptance in the Midwest, where fewer herbicides are used. However, it could be used here to control the quackgrass that wasn't killed in the previous crop. Of course, a lot will depend on how much the technology fee will be and that has yet to be determined."

While row-crop farmers have been planting RR varieties for several seasons, the technology has taken longer to reach the alfalfa industry.

"Alfalfa is a perennial, autotetraploid forage crop, quite different in many ways from corn, cotton, soybeans and canola - the other Roundup Ready crops that have been commercialized to date," says McCaslin. "These differences present some unique challenges in developing the technology in alfalfa.

"In addition, stringent molecular and product safety requirements must be met before regulatory approval can be granted for Roundup Ready alfalfa, adding to the development time."

He's been working with RR alfalfa since 1998. That's when Monsanto, Forage Genetics and Montana State University began a research collaboration to develop it.

The transgene in RR alfalfa is the same one used in other crops. RR alfalfa plants were tested extensively in 1999 field plots in Wisconsin, Indiana, Iowa and Idaho. At those locations, 4 qts of Roundup were applied per acre. Those plants have shown excellent Roundup tolerance and agronomic performance, says McCaslin.

"Over 90% of the seedlings established from a bag of Roundup Ready alfalfa will carry the Roundup Ready genotype," says McCaslin. "Preliminary results suggest that yields will be equal to or better than those of current commercial cultivars and we expect that improved weed control will result in improved quality potential."

After the long process of product development and regulatory approval is completed, Forage Genetics and Monsanto will license the technology to other seed companies for sale and/or development of their own RR varieties. j