March 28, 2011
 

US corn growers warned against flouting atrazine rules

As the 2011 cultivation season approaches, Wisconsin corn growers are reminded to abide by the state's rules on the use of the corn herbicide, atrazine, according to the state agriculture officials.

"Atrazine or products that contain atrazine cannot be used within an area where its use is prohibited," said Stan Senger, environmental quality section chief, Department of Agriculture, Trade and Consumer Protection. "There are 101 atrazine prohibition areas in Wisconsin that cover approximately 1.2 million acres of land. This includes land along the Lower Wisconsin Riverway."

Prohibition areas are drawn out when atrazine levels in a private well pass the state health standard of three parts per billion.

Farmers and pesticide applicators need to check the label and spot the active ingredients in the herbicide and not rely on the product name.

"Remember that many 'premix' herbicide products contain atrazine even though you would not know this from the product name itself," Senger said. "Any herbicide product that lists atrazine as an active ingredient cannot be used in a prohibition area."

Some of the most common atrazine-containing premix products used in Wisconsin are Lumax, Keystone, Bicep II Magnum, Harness Xtra and Marksman. Products that contain atrazine as the one active ingredient include Aatrex 4L and Aatrex Nine-O. Senger noted that more than 80 products registered for use in Wisconsin contain atrazine so he urges applicators to read product labels carefully. 

Knowing the locations of atrazine prohibition areas is also vital. Maps of Wisconsin's atrazine prohibition areas along with other product restrictions can be found on the department's website.

Senger advised growers to look at the maps every year for possible changes. "Most of the prohibition areas were created 10 or more years ago but through well sampling, laboratory tests and environmental investigations, we may add or modify an area through a rule revision," Senger said.

Sauk County has a new prohibition area that is beside the Lower Wisconsin River Valley. In Columbia County, more restricted acreage near Pardeeville joins two neighbouring prohibition areas. These areas will come into effect on May 1, 2011.

Finally, the mixing and loading of any atrazine product is forbidden unless the mixing and loading is done over a spill containment pad.

For fields that are not situated in a prohibition area, Wisconsin has more restrictions on the use of atrazine that apply throughout the state. On coarse texture or sandy soils, atrazine can be used at a maximum rate of 0.75 pounds per acre per year. On medium texture or loam soils, atrazine can be applied at one pound/acre if the field had received atrazine the previous year or 1.5 pounds/acre if it did not. Farmers can apply atrazine from April 1 through July 31. No fall applications will be entertained.