As tolerance evolves, UW researcher tests other herbicidesFarmers have hailed the development of crops such as sugar beets and alfalfa that tolerate applications of Roundup without damage.Roundup Ready crops aren't harmed by Roundup, which kills weeds along with most broad-leafed plants. That usually allows growers to apply it to replace several applications of other herbicides. Its use can reduce fuel costs and carries other benefits since, unlike other herbicides, Roundup leaves no soil residue.

Unfortunately, some weeds are starting to show resistance to Roundup, which means growers may have to try other herbicide treatments, said Andrew Kniss, a University of Wyoming researcher. But some herbicides also may damage crops, he said, so he's set up experiments to test plant damage from herbicide applications.

Kniss said at least three weed species have evolved tolerance to Roundup and that kochia has been reported in some parts of the country.

“If we get Roundup resistant kochia (weeds) up here,” Kniss said, “what are we going to do?”

Kniss is running test plots at the UW Powell Research and Extension Center just north of Powell to try new herbicide combinations. At last week's annual field day at the research center, Kniss said he and a team of graduate students are using aerial imagery to try to calculate whether applying different herbicides injures Roundup Ready beets.

“Roundup doesn't injure beets, but the other herbicides can,” he said.

Targets mark areas of the test plots. Kniss works with a pilot from a North Dakota company to create aerial images that Kniss can use to evaluate effects of different application rates and timing of those applications.