Idaho and Oregon growers were alerted June 11 about a possible case of glyphosate-resistant weeds in at least two sugar beet fields in the Treasure Valley area of Western Idaho and Eastern Oregon.
University of Idaho weed scientist Don Morishita posted the alert on the Pacific Northwest and Treasure Valley Pest Alert Network after being notified by growers who observed kochia weeds still growing in sugar beet fields that had been sprayed with Roundup.
Morishita did not know the particulars of either location as of press time.
Glyphosate is a weed killer that is the active ingredient in the herbicide Roundup produced by Monsanto Corp. The fields where the kochia was found still growing were planted with Roundup Ready sugar beets, which are developed by Monsanto and genetically modified to be resistant to glyphosate.
Morishita said no tests have been done yet to determine if the weeds are in fact resistant to glyphosate. But he said he thought it was important to let growers know about the issue because kochia is a widespread weed in this region.
Morishita said researchers are in the process of collecting samples for testing.
“I don’t want growers to get over-alarmed by it but on the other hand, I want them to be somewhat alarmed about it,” he said.
Trent Clark, Monsanto’s public and government affairs director, said there are several reasons a weed like kochia could have survived being sprayed with Roundup that don’t involve glyphosate resistance and “at this point, it could be nothing.”
“There are several possible explanations that don’t involve any genetic changes in the plant,” he said. But, he added, “This would be an incident that probably merits additional study to find out why this kochia is not responding to glyphosate control.”
Morishita said growers with Roundup Ready sugar beet or corn fields in this area should report any suspicious kochia escapes to their local crop consultant or adviser or extension educator.
“The bottom line is, if they do suspect it, we really want them to contact (us),” he said. “We don’t want any of these plants to go to seed.”