Crop Tech Corner

Resistant Weeds Near 60-Year Anniversary

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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Glyphosate resistance doesn't represent a new problem -- agriculture has been dealing with resistant weeds for 60 years. (DTN photo by Nick Scalise)

ROCKVILLE, Md. (DTN) -- This bi-monthly column condenses the latest news in the field of crop technology, research and products.


The phenomenon of resistant weeds has a big birthday coming up next year -- and it's older than you might think. Scientists have been documenting weed resistance to other herbicides for almost 60 years, according to a news release from the Weed Science Society of America.

The year 1957 was a big one for weeds. In a Hawaiian sugarcane field, scientists documented resistance to a synthetic auxin herbicide in a weed called spreading dayflower. That same year, wild carrot plants with the same type of resistance were found along the roadways of Ontario, Canada. In the past two decades, glyphosate resistance has gained notoriety for its near-dominance of the American farming landscape, but weeds have shown resistance to 160 different herbicides (and 23 of the 26 available chemical modes of action) around the world, the press release noted.

WSSA scientists hope the looming 60-year anniversary of this problem will drive home the danger of trying to manage weeds with a single mode of action. "It would be naive to think we are going to spray our way out of resistance problems," University of Georgia weed scientist Stanley Culpepper said in the release. "Although herbicides are a critical component for large-scale weed management, it is paramount that we surround these herbicides with diverse weed control methods in order to preserve their usefulness -- not sit back and wait for something better to come along."

See the WSSA press release here:….


Certain insect pests of wheat are getting harder to control, and scientists think climate change is at least partly to blame. In the past few years, Kansas State entomologists have noticed that planting after the "fly-free" date for Hessian flies in October is no longer consistently preventing infestations, according to Kansas Wheat press release. Even the most Hessian-fly-resistant varieties were showing Hessian fly problems, so the team of scientists took a closer look at 12 traditionally resistant varieties. They found that half could no longer be categorized as resistant to the Hessian fly.

The scientists believe two factors are at play, and one of them is likely temperature-related. Kansas State entomologist Mike Smith noted in the release that "some Hessian fly resistant genes in wheat are affected by higher temperatures, but we don't know enough about the pedigrees of these lines to know if that's the case" for some or all of these changes. "But the bottom line is, not only the climate changing but also something in the genetics of the varieties is changing. So that's what we're trying to get to the bottom of," he added. Higher temperatures and drought might also be behind the rising problems with wheat curl mite and Russian wheat aphid in the Southern Great Plains, Smith said.

See the press release from Kansas Wheat here:….


Researchers have been poring through the 30,000 genes of the corn genome ever since it was first sequenced in 2009. Now researchers from Cold Springs Harbor Laboratory in New York have broken into a surprising new wellspring of diversity within those genes. According to a press release from the laboratory, a new sequencing technique allowed researchers to document over 111,000 RNA messages delivered by these genes, 57% of which had never been identified before. Those messages direct the production of proteins that help shape the development and growth of the plant.

"It begins to reveal new functional parts that we didn't know about before," said USDA biologist Doreen Ware, who works at CSHL and was part of the discovery. "By having insight into what those other parts are and what they do, we begin to realize new ways of breeding corn, adapting it, for example, to changes in climate as average annual temperatures in growing zones continue to climb," she said in the press release.

You can see the press release here:…, and the study here:….

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Emily Unglesbee