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Posted 5 May 2009. PMN Crop News.

Be Mindful of Atrazine Setbacks and Best Management Practices

University of Minnesota.

St. Paul, Minnesota (April 27, 2009) —Atrazine is the third most widely-used corn herbicide in Minnesota, and according to the Minnesota Department of Agriculture (MDA), was used on 22 percent of Minnesota’s corn acres in 2007. Restrictions were placed on the use of atrazine (it is a Restricted-Use Pesticide, as is any product containing atrazine) after atrazine and its breakdown products were detected in ground and surface waters. Following required setback restrictions and voluntary Best Management Practices (BMPs) should help reduce the risk of potential impacts of atrazine on our water resources.


The majority of atrazine applied in Minnesota is through pre-mixed products where it may not be readily apparent if atrazine is a component or not. Check the active ingredient listing on the herbicide label to determine if atrazine is included. The MDA also has a listing of products that contain atrazine for handy reference at

When using a product that contains atrazine, be sure to check the label for use restrictions. Setback requirements for an atrazine application include a minimum of 50 feet from wells and sinkholes, 66 feet from points where field runoff enters intermittent and perennial rivers and streams, 66 feet from standpipes on terraced fields if atrazine is not incorporated or if no-till is not used, and 200 feet from lakes. Some product labels contain language where a 66-foot setback is required from all standpipes, regardless if the field is terraced. Always refer to the herbicide label for specific requirements on the product you are using. The MDA website also provides helpful discussion on label language and interpretations on atrazine restriction requirements (

Following voluntary BMPs for atrazine can also help reduce potential impacts on our water resources. BMPs developed for atrazine can be found on the MDA website listed above. One of these practices includes using a reduced rate of atrazine.

Researchers at the University of Minnesota evaluated reduced rates of atrazine tank-mixed with several postermergence broadleaf herbicides at Rochester, Minn. (2007 and 2008) and the Southwest Research and Outreach Center in Lamberton (2008). A 0.5 pound per acre rate of atrazine was used in the trial, which is below the BMP rate for atrazine. Results from this trial demonstrated that although results varied by year and location, the addition of a low rate of atrazine can enhance weed control and lead to increased yield, with only a minimal increase in input costs. This trial also compared potential replacements for atrazine. Further details on this trial can be found in the “2008 Southern Minnesota Regional Research and Demonstration Summary” on the Southwest Research and Outreach Center website at

Atrazine has been a tool in weed management for decades. As producers plan herbicide applications for this growing season, be mindful of required setbacks and voluntary BMPs to help reduce or prevent potential impacts of atrazine on our water resources.

Lizabeth Stahl
University of Minnesota Extension