Roundup Ready alfalfa varieties performed well in a 2011 variety trial at the University of Wisconsin’s Arlington Agricultural Research Station, reports Dan Undersander, Extension forage agronomist at the university.

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

Only seeding-year data is available, since planting the transgenic alfalfa varieties was prohibited prior to this year, he notes. The highest-yielding commercially available variety in the Arlington trial was a Roundup Ready variety treated with Roundup herbicide. However, due to field variability, alfalfa varieties must have a least significant difference of 0.5 ton/acre to be truly different, and several conventional and Roundup Ready varieties were not significantly different from the top variety.

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

Yields of the transgenic varieties were not significantly different whether they were treated with Roundup or Butyrac 200 and Poast Plus, says Undersander.

More information about forage variety trial results can be found at