The performance of Roundup Ready alfalfa varieties is being evaluated in University of Wisconsin-Madison/Extension alfalfa variety trials according to Dan Undersander, UW-Extension Forage Agronomist.

He noted that only seeding year data is available since no one could plant Roundup Ready alfalfa varieties prior to this year due to a court injunction prohibiting such planting.

The highest yielding commercially available variety in the 2011 seeding at Arlington Agricultural Research Station was a Roundup Ready variety in the treatment receiving Roundup. However, due to field variability, alfalfa varieties must have a least significant difference of at least 0.5 t/a to be truly different and several conventional and Roundup Ready varieties were not significantly different from the top variety.

“Roundup Ready varieties were generally in the upper half of the yield range at Arlington,” said Undersander. “This would indicate that alfalfa varieties have no yield drag due to the Roundup Ready trait.”

The trial was conducted both with Roundup Ready varieties planted with non Roundup Ready varieties in a standard trial and treated with the same herbicides. Butyrac 200 and Post Plus were used to control weeds in these trials to minimize herbicide injury. The Roundup Ready varieties were also planted in a separate trial treated with Roundup.

Undersander said, “Yields of the Roundup Ready varieties were not significantly different whether Roundup Ready alfalfa varieties were treated with Roundup for herbicide control compared to those receiving the butyric 200 and Post Plus.”

More information about forage variety trial results can be found at

Source: University of Wisconsin Cooperative Extension