Field tests seek new control methods for resistant ragweed in cotton crops

December 7, 2012

Giant ragweed lives up to its name, towering over crops and choking out surrounding plant species. Just one ragweed plant per square meter has been shown to reduce crop yields 45 to 77 percent. Now giant ragweed has evolved resistance to the herbicide glyphosate, which had been effective at controlling the weed.

The journal Weed Technology reports results of a field test with giant ragweed and WideStrike®, a cotton variety resistant to glyphosate and glufosinate herbicides. Planting this new variety of cotton will allow farmers to treat ragweed without negatively affecting their crop yield.

Giant ragweed has extended its reach from Midwestern corn and into Southern . Once a bystander in fence rows and ditch banks, giant ragweed now grows rapidly, has an extended period of emergence, and is able to thrive in many environments. These features have made it a major competitor with .

Few postemergence herbicides are providing effective control of resistant giant ragweed. Glufosinate, which currently has no known broadleaf resistance, proved one of the most effective in this study. In 2009, 2010, and 2011, Widestrike cotton was planted in a Tennessee grower's field known to have a population of glyphosate-resistant giant ragweed.

Unfortunately, many of the herbicide treatments in this study reduced cotton yield along with the resistant giant ragweed. Of 12 treatments tested, glufosinate alone, glufosinate plus glyphosate, glyphosate plus pyrithiobac, and glufosinate plus fluometuron were the most effective. The only combination that showed 90 percent control of giant ragweed without reducing crop yield was glufosinate followed by another treatment of glufosinate. However, growers will need to use multiple methods of in the future to prevent weeds from developing resistance to glufosinate as they have with other herbicides.

Explore further: Farmers relying on roundup lose some of its benefit

More information: www.wssajournals.org/doi/full/10.1614/WT-D-12-00042.1

Related Stories

Farmers relying on roundup lose some of its benefit

April 14, 2009

(PhysOrg.com) -- Roundup Ready crops have made weed control much easier for farmers, but a new study shows their reliance on the technology may be weakening the herbicide's ability to control weeds.

Herbicide diversity needed to keep Roundup effective

July 13, 2009

Using a diverse herbicide application strategy may increase production costs, but a five-year Purdue University study shows the practice will drastically reduce weeds and seeds that are resistant to a popular herbicide.

Old herbicides enlisted in new 'war on the weeds'

May 23, 2012

The emergence of weeds resistant to the most widely used herbicide is fostering a new arms race in the war against these menaces, which cost society billions of dollars annually in control measures and lost agricultural production. ...

'Superweeds' linked to rising herbicide use in GM crops

October 2, 2012

A study published this week by Washington State University research professor Charles Benbrook finds that the use of herbicides in the production of three genetically modified herbicide-tolerant crops—cotton, soybeans and ...

Recommended for you

Fighting explosives pollution with plants

September 3, 2015

Biologists at the University of York have taken an important step in making it possible to clean millions of hectares of land contaminated by explosives.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.