A new corn hybrid offers growers more options for weed management and may delay the evolution of herbicide-resistant weeds, extending the utility of some existing herbicides. The new hybrid contains two genes, hra and gat4621, combined in a molecular stack and inserted into the corn line 98140.

The authors of the article, "Response of 98140 Corn with gat4621 and hra Transgenes to Glyphosate and ALS-Inhibiting Herbicides" in the March/April 2009 issue of Weed Science studied how this corn hybrid responds to glyphosate and acetolactate synthase (ALS)-inhibiting herbicides. They found a high level of resistance to both.

Glyphosate-resistant crops, such as corn, cotton, and sugarbeet, allow growers to apply glyphosate to control weeds. This has been an effective method of weed control for the past decade; however, weeds are now adapting to glyphosate.

In the hybrid crop, when this stack of glyphosate and ALS herbicide resistance maintains its natural tolerance to commonly used selective herbicides, further opportunities are created, biologically, to manage weeds and delay the evolution of glyphosate-resistant weeds.

Both pre-emergence and post-emergence tests were conducted on the 98140 corn, which is under commercial development.

"On a rate basis, the positive 98140 isoline with a single copy of the gat4621 gene is more than 1,000-fold more resistant to glyphosate than a negative isoline without the transgene," according to the authors. "Similarly, the positive 98140 isoline with the hra gene is more than 1,000-fold more resistant to ALS-inhibiting herbicides at the whole-plant and enzyme level."