When Virginia Tech Small Grains Specialist Wade Thomason asked a group of wheat growers at a recent field day if they knew about Clearfield wheat, he got mostly blank stares and no response.

After explaining how the new wheat weed management system works, the Virginia Tech researcher got plenty of questions.

Clearfield wheat isn’t exactly new. BASF began working with the system back in the 1980s and the first Clearfield varieties were released nearly a decade ago. Clearfield wheat is tolerant to the herbicide Beyond. The first Clearfield wheat variety was called Above. Above and Beyond was a good marketing ploy, but has been slow to be accepted by Virginia farmers, Thomason points out.

In more recent years Virginia Tech Plant Breeder Carl Griffey has included, first one gene and now two genes with tolerance to Beyond herbicide, into varieties more commonly grown in Virginia.

Jamestown, a popular wheat variety in Virginia, containing both one and two herbicide tolerant genes, was tested at Virginia Tech’s Eastern Virginia Agricultural Research and Extension Center in Warsaw, Va. “With the two genes, we think we have the herbicide resistance we need, now we have to find the right fit with different varieties for growers in the upper Southeast,” Thomason says.

Beyond, and similar herbicides, inhibit the activity of the enzyme, acetolactate synthase (ALS), also known as acetohydroxyacid synthase (AHAS), which is necessary for the biosynthesis of the branched chain amino acids valine, leucine, and isoleucine.

In response to a Beyond herbicide application, ALS is inhibited in susceptible plants depriving them of the previously mentioned, essential amino acids. This causes the eventual death of treated plants.

Clearfield wheat (and other plant crops) is not a genetically modified organism (GMO). It is a mutation, which produces an altered form of the ALS enzyme that is not affected by the herbicide at normal application rates. Beyond herbicide received EPA Federal registration for use in Cleafield wheat in December 2001.