Respect the Rotation: Glyphosate-Resistant Weeds One Year Later


RESEARCH TRIANGLE PARK, NC.  — Growers, consultants, weed scientists, researchers and government agency officials who participated in the July 2010 launch of the Respect the Rotation™ initiative have taken measureable steps toward progress in the fight against the proliferation of glyphosate-resistant weeds. But university experts still believe the system will fail if current practices continue.

There is enough of an ominous threat that government officials have taken an interest in the topic. With that knowledge, one initiative to come from the 2010 Respect the Rotation field day urges growers to remember management practices from a time before glyphosate resistance was widespread and diverse management practices discouraged the development, and additional cost, of resistant weeds.

“Glyphosate-resistant marestail costs soybean growers an added $11.50 per acre,” said Jason Norsworthy, associate professor of weed science at the University of Arkansas and a key member of the Weed Science Society of America (WSSA) who is working with the Environmental Protection Agency to develop guidelines for proper resistance management practices. “Glyphosate-resistant Palmer pigweed costs cotton growers $19.45 per acre. Resistance is impacting land values, conservation tillage and more. The system, the way it is currently set up, is not sustainable.”

Norsworthy and other WSSA members are working diligently with other government agencies to develop incentives for proper stewardship of glyphosate-tolerant technologies and encourage proactive management strategies. This cooperation will spur producers to stay ahead of weed resistance and raise a profitable crop.

In a move to make rotation easier for growers, Bayer CropScience is voluntarily labeling all herbicide modes of action on herbicide containers for easy identification. “If growers can see the numbering system associated with various chemistries and easily identify what mode of action they’re applying, they can better identify opportunities for herbicide rotation” said Andy Hurst, product manager for Bayer CropScience. “Without that knowledge, it is easy to apply the same mode of action over and over, encouraging the development of resistance.”


Flag the Technology

Another proposal from the 2010 Respect the Rotation event is the Flag the Technology program spearheaded by the University of Arkansas. Colored flags are placed around a field to help prevent herbicide misapplication and to warn of technology that is sensitive to potential off-target chemical drift. The colored flags help applicators easily identify what technology is planted to a particular field.

The University of Arkansas has promoted the effort and helped standardize the size of the flags and what each flag color means. LibertyLink® fields are identified with green flags, signifying it’s tolerant to Ignite® herbicide. Roundup Ready® varieties are marked with white flags. Conventional fields are identified with the color red.

Reports indicate fields have been saved from accidental misapplication by the colored flags.

“This will help growers be conscientious of what’s in their fields and their neighbors’ fields,” Hurst said. “Rotation encourages diversity and leads to stronger management against resistant weeds. The flag system offers growers who rotate herbicide-tolerant traits peace of mind.”


Looking Ahead

Midwest attendees of the 2010 Respect the Rotation meetings were shocked at the scope and breadth of glyphosate-resistant Palmer pigweed in the Mid-South. To see firsthand how much money was invested in Palmer pigweed control and to watch fields being plowed under because of out-of-control weeds, was a wakeup call to many.

In 2011, Bayer CropScience is taking the Respect the Rotation story to the Midwest. Building on the success of last year’s Respect the Rotation event, this year there will be six field days throughout the Midwest. Topics will center on weed resistance – what the problem is and how to manage it – on sites from Nebraska to Ohio to southern Illinois.

“Producers are offered an intimate look at what weed resistance looks like locally and what it means for their farms,” Hurst says. “We’ve teamed with university experts across the Midwest to set up plots that demonstrate glyphosate weed resistance and the best programs available for control based on local conditions.”

Respect the Rotation is an initiative to elevate the importance and grower adoption of herbicide diversity. The Respect the Rotation Field Tours scheduled for 2011 are bringing the issues to the doorsteps of those who can benefit most from its message. “We’re moving in a positive direction and offering choices to break the cycle of continuous glyphosate use,” Hurst says. “I’m looking forward to making even bigger strides this year.”

2011 Respect the Rotation events will be held at:

Tuscola, Ill.                              July 11, 12

Portageville, Mo.                     August 2

Red Bud, Ill.                            August 9, 10

Clarksburg, Ohio                     August 23

Beaver Crossing, Neb.            August 24

Ames, Iowa                             Sept. 13, 14

To find out more about weed resistance management or Respect the Rotation, visit our website at