Diversity key to glyphosate issue

By Forrest Laws, Farm Press Editorial Staff

Could glyphosate, arguably one of the world’s most important herbicide compounds, become practically useless for all but a few “niche” markets in the next few years? Steve Powles thinks that is a real possibility.

In the last 15 years, glyphosate has become one of the most widely used herbicides in the world, eclipsing even atrazine as the workhorse of chemical weed control in row crops and a myriad of other uses.

So could glyphosate, arguably one of the world’s most important herbicide compounds, become practically useless for all but a few “niche” markets in the next few years? Steve Powles thinks that is a real possibility.

Powles, professor of plant biology at the University of Western Australia and director of the Western Australia Herbicide Resistance Initiative, gave that assessment during remarks at the Pan-American Weed Resistance Conference in Miami Jan. 19. The conference was attended by 284 scientists and media representatives from North America and South America.

“Glyphosate will be driven to redundancy in the cotton, corn and soybean belt,” said Powles, a widely respected authority on herbicide resistance. “Outside of these areas of the U.S., then glyphosate should continue to be effective because it is not massively used.

“Within the cotton, corn and soybean belt the massive reliance on glyphosate means that it will be driven to redundancy because many of the big driver weeds such as Palmer pigweeds, waterhemp, ragweed and Johnsongrass will be resistant. There may be many weed species still controlled by glyphosate, but glyphosate will fail on the driver weeds and that means overall failure.”

Weed scientists from throughout the Western Hemisphere talked about the increasing tide of documented cases of glyphosate resistance during the conference, which was sponsored by Bayer CropScience, though none of the forecasts were quite as dire as that of Powles.

That glyphosate could fade to near-oblivion as a herbicide would be “lamentable,” he said, “because glyphosate is one of the world’s greatest herbicides. It works on 140 weed species. It is a one-in-a-100-year discovery, and we’ll never see another herbicide like it.”