New Regulation on Atrazine Public Comment Period Closes October 7.

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The Environmental Protection Agency (EPA) has proposed additional mitigations and regulations on the use of atrazine.  The open comment period will close this Friday October 7.   If you are interested in commenting see this link. I know that it is a very busy time of year but please consider making a comment on this topic. You all are the experts since you steward this herbicide, on many acres, each spring and your comments have more value than many that are sent.

The additional proposed regulations are complex with the first set of regulations affecting all use of atrazine in the United States.  They include:

  • Prohibit application when soils are saturated or above field capacity (i.e., the soil’s ability to retain water);
  • Prohibit application during rain or when a storm event, likely to produce runoff from the treated area, is forecasted to occur within 48 hours following application;
  • Prohibit aerial applications of all formulations; and
  • Restrict annual application rates to 2 pounds of active ingredient or less per acre per year or less for applications to sorghum, field corn, and sweet corn.

Of those four new proposed rules, the biggest change for Tennessee corn and grain sorghum users is the reduction from 2.5 lbs/A to 2 lbs/A total season use rate.

The next set of proposed regulations does not affect all of Tennessee but rather a handful of counties that the EPA model estimates would have an atrazine concentration of more than 3.4 or 9.8 ug/L. The map for the additional regulations listed below is based on watersheds and not counties.  The best I can tell from the map (Figure 1) is that the impacted Tennessee counties would include the counties bordering the Mississippi River so Shelby up to Lake as well as Obion, Weakley, Henry, parts of Crockett and Gibson as well as the Middle Tennessee counties of Franklin and maybe parts of Macon and Robertson.  The fields where atrazine is applied in those counties must have some additional runoff mitigation tactics in place to be on label.

The additional mitigation pick list for those counties include:

  • No preemergence applications (to the crop)
  • Greater than or equal to 30 ft vegetative filter strips on A and B hydrologic group soils
  • Greater than or equal to 100 ft vegetative filter strips on C and D hydrologic group soils
  • Grassed waterway • Field border • Irrigation water management
  • Cover crop
  • Contour buffer strips
  • Contour farming
  • Terrace farming
  • Strip cropping
  • Soil incorporation to a depth of 2.5 cm (1 in)
  • No tillage/ reduced tillage

The way I read this would suggest that a farmer in Dyer county (Pink in map) on soil that is NOT on highly erodible land (HEL) would have to comply by using two runoff reduction practices in order to apply up to 2.0 lbs/A of atrazine. While for I assume Lake and Obion counties (Blue on map) 2 mitigation tactics only allow a rate up to 0.8 lbs/A.

Most Tennessee fields are in reduced or no-till so by default everyone would start with one.  Another one that is pretty common in West Tennessee is not using atrazine PRE but only POST which qualifies as a runoff reduction practice.  Where these regulations become more cumbersome is on highly erodible land where 4 runoff reduction practices must be in place in order to apply atrazine at a rate that is effective.  In looking at the pick list some of those practices, though not rare like using a cover crop, are not as ubiquitous as no-till.

The EPA has stated they are particularly interested in additional mitigation options for atrazine users to employ so that they can use the herbicide on their fields. If you have some additional ideas please let the agency know.

This graphic shows areas of the country where atrazine use would exceed limits imposed under the proposed EPA regulations. Source Brian O’Conner; Crop Protection. Posted August 5, 2022.


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