Variety, they say, is the spice of life. And the same philosphy is needed to combat herbicide resistance in weeds.


If you continually use glyphosate herbicides, chances are the weeds and their seeds will develop a tolerance or resistance to it over the years, according to a five-year study conducted by Purdue University associate weed science professor Bill Johnson.

By changing management and rotating to different herbicide modes of action, you can greatly reduce chanceds for marestail, also known as horseweed, to develop resistance to the broad-spectrum hericide.

"Another herbicide application is expensive, and it means more trips across the field," Johnson said in a news release. "But we can reduce the population and density of resistant weeds, which increases the crop yield potential."

The results of Johnson's five-year study were published in the journal Weed Science.

Marestail was the first weed to develop resistance to glyphosate.

A handful of other weeds have since been identified as having resistance to the herbicide, too.

Johnson's study found that farmers should diversify the herbicides they use.

"Glyphosate-resistant marestail develops very quickly in a field. Populations reach staggering levels of infestation in about two years after it is first detected," Johnson said in the release. "For us, marestail being the first weed that developed resistance showed that a weed-management system that is solely reliant on glyphosate is starting to break down. However, a system that incorporates other herbicides with glyphosate can be sustainable for quite some time."