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No Dicamba in July; South Dakota Sets Cut-Off Date to Reduce Drift Damage

The South Dakota Department of Agriculture has set this year’s cut-off date for applying the controversial and unneighborly herbicide dicamba: when soybeans reach the R1 growth (beginning bloom) stage, 45 days after planting, or June 30, whichever comes first.

South Dakota restricted dicamba application based on weather and growth stage last year but fixed no clear cut-off date. South Dakota Department of Agriculture agronomy services program manager Tom Gere said last year that South Dakota struggled to enforce those looser restrictions and that “the majority of our sales that we’ve looked at for the last two years resulted in applications that were made after July 1.” Proper enforcement of the new 2019 cut-off date would thus have significant impact on soybean farmers’ operations. It could also significantly reduce damage to neighbors crops and trees: according to the South Dakota Agri-Business Association, “40% of the dicamba drift investigations had application dates after July 1.”

South Dakota is using something called the 24(c) label to impose this cut-off date. The label is named for Section 24(c) of the Federal Insecticide, Fungicide, and Rodenticide Act, which allows states to issue pesticide labels that supplement the federal labels. The Trump Environmental Protection Agency is signaling that it may stop states from using 24(c) labels to impose greater restrictions on dicamba, since 24(c) authorizes additional uses for “special local needs,” not reduced uses:

Due to the fact that section 24(a) allows states to regulate the use of any federally registered pesticide, and the fact that some states have instead used 24(c) to implement cut-off dates (and/or impose other restrictions), EPA is now re-evaluating its approach to reviewing 24(c) requests and the circumstances under which it will exercise its authority to disapprove those requests. Before making any changes in this regard, EPA intends to take public comment on any potential new approaches before adopting them.

EPA is not making any immediate changes in this area and does not expect any potential changes will impact 24(c) requests that states submit ahead of the 2019 growing season [Environmental Protection Agency, statement on FIFRA 24(c) registrations, 2019.03.19, retrieved 2019.04.03].

If it blocks the ability of states to impose greater restrictions on dicamba, the EPA will be moving in the opposite direction of growing scientific and public concern. University of Arkansas weed scientist Jason Norsworthy said at a February conference that dicamba may damage entire landscapes through “atmospheric loading”:

Norsworthy likens the effect to smog in Los Angeles. “When you look at Los Angeles, it’s not just one vehicle adding emissions or causing the problem,” he said. “It’s the fact that you have thousands upon thousands of vehicles within a very small area contributing to this issue and as a result, everyone in the region is impacted. I see this not really being any different from what we’re observing in areas where we have heavy use of dicamba and the volatility that is ultimately occurring.”

That effect would explain the widespread injury found in certain regions where a lot of dicamba spraying occurred, such as northeast Arkansas and southeast Missouri in the past two years, both Norsworthy and University of Missouri weed scientist Kevin Bradley told DTN. In many of these injury investigations, the dicamba injury to vegetation was clear but no individual culprit could be identified, because dicamba was used so extensively in the area, Norsworthy and Bradley noted.

“With atmospheric loading of volatile herbicides such as we have observed in northeast Arkansas, the Bootheel of Missouri and west Tennessee, you will have landscape damage with no obvious source of where the damage came from,” Norsworthy said [Emily Unglesbee, “Dicamba Data Download,” DTN Progressive Farmer, 2019.02.15].

Emily Unglesbee writes that increased attention to dicamba drift damage may prompt wider regulation:

Ultimately, dicamba’s visibility may soon move this issue out of agriculture and regulators’ domain, and into the public’s. In August of 2018, I toured the small town of Waverly, Nebraska, with members of the Nebraska Forest Service. In a beautiful little recreation center called Wayne Park, tucked in among residential streets, nearly every tree we walked past bore the same distinctive signs — cupped, crinkled leaves and shrunken canopies. At nearby tree nurseries, we walked row after row of dicamba-damaged redbuds, Kentucky coffee trees and a wide range of oak trees.

Nebraska Forest Service landscape specialist Justin Evertson has been noticing herbicide injury to the state’s trees for years, especially in the spring. But only now that dicamba has increased the visibility of this problem does he have funding available to study its long-term effects. For the next two years, led by South Dakota State University, Nebraska will join five other Midwestern states to conduct surveys of herbicide injury to trees in rural America.

Their findings will be public. And we won’t be able to unsee them.

Agrichemical companies, regulators and farmers have perhaps one more year, maybe two, to take ownership and responsibility for off-target dicamba movement. After that, they may have to accept the consequences of an unsympathetic public calling the shots on this chemical’s use [Emily Unglesbee, “How Dicmaba’s Visibility Could Change Ag Pesticide Use Forever,” DTN Progressive Farmer, 2019.03.27].

Most of the corporate-run applicator trainings for dicamba products in South Dakota have already taken place; the Department of Agriculture says Monsanto has one more training scheduled for Friday, April 5, here in Aberdeen, but neither the SD Agri-Business Association nor CHS Northern Plains include that event on their list. Applicators must have taken training this year to use dicamba. This guidance from Purdue Extension offers some of the guidelines trained and responsible applicators will follow when using dicamba.


  1. Nick Nemec 2019-04-03

    Two years ago I noticed the leaf cupping that indicates dicamba damage in my soybeans. My damage was fairly minor but a field a couple miles away had what I would classify as severe damage. I came out of the season considering myself lucky it wasn’t worse. Last year I didn’t want to take the chance of more severe damage, decided to pay the Monsanto protection fee and planted the dicamba resistant beans. Monsanto didn’t threaten to break my knee caps but they metaphorically threatened to knee cap me and I succumbed to the implied threat.

  2. mike from iowa 2019-04-03

    What happens to the deadline if Mother Nature tosses a really cold wet Spring at farmers and they can’t plant beans before June 30th?

    Well and truthfully stated about then knees, Mr Nemec. Farming has become a captive industry for Bayer/Monsanto.

  3. Debbo 2019-04-03

    “If it blocks the ability of states to impose greater restrictions on dicamba, the EPA will be moving in the opposite direction of growing scientific and public concern.”

    What, again?

    So dicamba turns the land brown and dead except for what? Soybeans? Corn? Good lord, what a hellish way to “pharm.”

    That’s probably what turned it red and dead. The Martians used dicamba.

  4. Cory Allen Heidelberger Post author | 2019-04-05

    Monsanto as Mafia, fancy seeds as protection money—excellent, Nick!

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