Now that lab tests have confirmed that some kochia weeds in the Treasure Valley area are resistant to the herbicide Roundup, researchers will try to determine how widespread they are and develop recommendations to control them.
Oregon State University and University of Idaho researchers will discuss the situation and recommendations with sugar beet growers during their winter meetings.
OSU weed scientist Joel Felix alerted growers Aug. 4 that tests performed by Colorado State University scientists confirmed glyphosate resistance in kochia weeds found in two sugar beet fields in Eastern Oregon.
Samples of suspect weeds collected from two sugar beet fields in southwestern Idaho were sent to Montana State University by UI weed scientist Don Morishita. He expects those results soon.
Glyphosate is the active ingredient in Roundup. The fields where the resistant and suspect weeds were discovered had been planted with Roundup Ready sugar beets, which are genetically modified by Monsanto Corp. to resist Roundup.
The weeds survived being sprayed with Roundup.
The Southwestern Idaho and Eastern Oregon farming communities are closely linked, and UI and OSU researchers are working together to better understand the issue and develop control recommendations for sugar beet growers.
That will require understanding how widespread the problem is in this area and growers can help, Felix said.
Researchers will scout sugar beet fields in the region at the end of the season and collect seed from suspicious kochia plants. The seed will be used to grow new plants that will be sprayed with Roundup to determine if they are glyphosate-resistant.
“Then we’ll be able to know the extent of the distribution of glyphosate-resistant weeds in this region,” Felix said.
He said sugar beet growers should report any suspicious kochia weeds to him, extension educators or crop consultants.
“The important thing is to call someone so we get an idea of what is going on,” Felix said.
Morishita said it’s also important for growers, if possible, to remove kochia weeds that have escaped being sprayed with Roundup to minimize the buildup of resistant seeds in the soil.
“I think the infestation is maybe small enough yet that we can try to hold this thing off by removing escapes in the field,” he said.
Felix said the discovery of glyphosate-resistant kochia weeds will require sugar beet growers to include other herbicides in the mix.
“They are going to have to include other herbicides in their spraying,” he said. “It’s not going to be Roundup by itself any more if one wants to have full control of kochia.”
He said crop rotation will be another important tool so that other weed control herbicides can be used that have different modes of action than glyphosate.
That will increase costs somewhat, Felix said.
Rupert farmer Duane Grant, chairman of the Snake River Sugar Co., said the emergence of glyphosate-resistant kochia weeds will complicate weed control somewhat for sugar beet growers in this area, but he said the industry will continue to benefit from Roundup Ready sugar beets.
“Clearly, the sugar beet industry has benefited by biotechnology and the ability to use glyphosate to control weeds in sugar beets,” he said. “The emergence of glyphosate-resistant weeds … complicates weed control a little bit in sugar beets. But I don’t think it’s anything we can’t manage through.”