Monsanto sales representatives and field agronomists are prepared to assist Indiana and Ohio growers in managing and minimizing the risk of glyphosate-resistant giant ragweed. Researchers at Purdue University and the Ohio State University jointly announced the recent discovery of separate populations of giant ragweed in Indiana and Ohio that exhibit low levels of resistance to glyphosate (Glyphosate-resistant giant ragweed confirmed in Indiana, Ohio).

“We have provided in-depth training for our sales force as well as our local field agronomists on how to assist growers in making their weed management decisions next year,” says Dr. Jennifer Ralston, Roundup Technical Manager. Monsanto continues to collaborate with academics and support studies on the most effective ways to control weeds in a Roundup Ready system.

“More than ever, growers are seeing the benefits of the Roundup Ready system in corn and soybeans,” says Ralston. This year alone, Monsanto is expecting an increase in Roundup Ready Corn 2 acres from 32 million acres to 40 million acres based on early season orders “However, we want to make sure farmers are choosing the weed control options that will minimize the risk for glyphosate resistance,” says Ralston. “Farmers should use a pre-emergence residual herbicide in the Roundup Ready system to help manage early season weed control and reduce the pressure on glyphosate.”

Purdue Extension Weed Scientist Bill Johnson agrees.

“Growers can’t afford NOT to apply a pre-emergence herbicide in the Roundup Ready system,” says Johnson, one of the scientists who discovered the resistant giant ragweed. “A pre-emergence residual herbicide in Roundup Ready soybeans and Roundup Ready Corn 2 protects against early season weed competition and can maximize yield.” In recent studies, Johnson and Ohio State University Weed Scientists Mark Loux and Jeff Stachler demonstrated that a pre-emergence herbicide used prior to a post-glyphosate application increased yield by 4 to 9 bushels an acre.

Some other giant ragweed populations have been confirmed resistant to ALS herbicides in Indiana and Ohio, reducing herbicide choices for tank-mix recommendations. For the growers that are experiencing poor control of giant ragweed in Roundup Ready Corn 2 or Roundup Ready soybeans, Monsanto provides the following recommendations:

• In Roundup Ready® soybeans – Use a pre-emergence residual product at planting such as FirstRate® or Gangster®. Tank mix Roundup WeatherMAX with Cobra®, Flexstar®, or FirstRate® if post-emergence giant ragweed control is needed.

• In Roundup Ready Corn® 2 – Use a pre-emergence residual containing atrazine, such as Harness Xtra or Degree Xtra at planting. Tank mix Roundup WeatherMAX with 2,4-D or dicamba (Clarity®, Banvel® or Distinct®) if post-emergence giant ragweed control is needed.

Monsanto also recommends growers consider the benefits of a corn-soybean rotation, including the ability to use different herbicides and alternative cultural practices and the disruption of disease and insect pressure.

The Ohio State University and Purdue University recommendations continue to include glyphosate as a key component in the weed control program, utilizing a residual herbicide or additional pre-emergence burndown product to potentially reduce weed populations and allow for more timely applications of glyphosate. This will also help manage other weeds in the field. Monsanto supports these recommendations as effective weed management strategies in Roundup Ready crops.

For more information on weed management recommendations for Roundup Ready crops, please visit www.weedresistancemanagement.com. The National Corn Growers Association and the American Soybean Association offer weed resistance management training modules on-line at their Web sites at www.ncga.com and www.soygrowers.com, respectively.

Monsanto Company is a leading global provider of technology-based solutions and agricultural products that improve farm productivity and food quality. For more information on Monsanto, see: www.monsanto.com.