{"id":5264,"date":"2017-11-13T01:59:53","date_gmt":"2017-11-13T07:59:53","guid":{"rendered":"https:\/\/agrilife.org\/texasaglaw\/?p=5264"},"modified":"2026-04-17T15:24:42","modified_gmt":"2026-04-17T20:24:42","slug":"dicamba-update","status":"publish","type":"post","link":"https:\/\/agrilife.org\/texasaglaw\/2017\/11\/13\/dicamba-update\/","title":{"rendered":"Dicamba Update (Part I)"},"content":{"rendered":"

Dicamba will likely go down as the biggest agricultural issue in 2017.\u00a0 This post will discuss some background information and then address several recent developments regarding the herbicide dicamba.<\/p>\n

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Photo by Chris Bennett, Farm Journal<\/p><\/div>\n

Background<\/strong><\/p>\n

The herbicide dicamba has been in use since the 1960’s.\u00a0 In 2012, it was the 5th most used herbicide worldwide.\u00a0 The chemical, marketed under names including Clarity and Banvel, kills broadleaf weeds.<\/p>\n

Things changed in the last few years when several agricultural businesses sought to alleviate concerns with weeds that had become resistant to the common herbicide glyphosate (the active ingredient in Roundup).\u00a0 Companies including Monsanto, BASF, and DowDupont developed genetically modified seeds for soybeans and cotton that possessed a dicamba tolerance.\u00a0 Thus, rather than applying glyphosate over the top of growing crops, farmers who planted these new seed\u00a0varieties would be able to apply dicamba to growing crops that are tolerant to the chemical.\u00a0 This would allow farmers to combat the weeds that were resistant to glyphosate.\u00a0 In addition to these genetically modified seeds, the companies developed corresponding herbicides.\u00a0 For example, Monsanto touted its “cropping system” of dicamba-tolerant seeds called Xtendflex and XtendiMax herbicide containing the active ingredient dicamba.\u00a0 The new herbicide products were advertised as being less volatile and safer than prior formulations.<\/p>\n

In 2015, Monsanto began selling its Xtendflex cotton seeds.\u00a0 In 2016, Monsanto’s Xtendflex soybean seeds were on the market.\u00a0 However, despite selling these seeds for the 2015 and 2016 crop years, the corresponding herbicide, XtendiMax, was not approved by the EPA for sale until November 2016.\u00a0 Other companies also developed herbicides to be used with the tolerant seeds.\u00a0 Dow received EPA approval for its Engenia product in December 2016 and DuPont’s FeXapan being approved in February 2017.\u00a0 At the time of approval, these herbicide products were approved for 2 year periods and were classified as general use pesticides–meaning that no pesticide applicator license or certification was required to purchase or apply.<\/p>\n

In addition to receiving EPA approval and labeling under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), the products had to be approved for use in individual states as well.\u00a0 States can issue an approval or not, and can impose various additional requirements in addition to those included on the federally approved label.\u00a0 For example, in Arkansas, pesticide use is governed by the Plant Board.\u00a0 To date, the Monsanto XtendiMax product has never been approved for over-the-top crop use in Arkansas.\u00a0 The BASF Engenia herbicide was approved in 2017, but then in June, over-the-top dicamba use was banned by the Plant Board.\u00a0 In Texas, dicamba use was limited when it was listed as a “special use” and “regulated use” pesticide, unless it was to be applied in accordance with an approved label to transgenic auxin herbicide-tolerant crops, by ground, with wind speeds not exceeding 10 miles per hour.<\/p>\n

Drift Complaints<\/strong><\/p>\n

Unfortunately, the rollout of these new crop\u00a0systems was not as smooth as the companies would have hoped.\u00a0 Complaints of drift damage to neighboring fields began pouring in.<\/p>\n

Even before the new dicamba formulations were approved for use, drift complaints were prominent across the South.\u00a0 In Tennessee, for example, there were approximately 40,000 acres destroyed by dicamba drift in 2016.\u00a0 Given that there was no dicamba formulation available for over-the-top application approved by the EPA during the 2016 growing season, it is likely that farmers who purchased the dicamba-tolerant seeds applied older, potentially more volatile versions of dicamba and applied them off-label to their crops.<\/p>\n

These issues did not end when the new herbicides were available for use.\u00a0 The University of Missouri reports that drift damage from dicamba has been reported in 21 states.\u00a0 From January to September 2017, there were more than 963 alleged misuse complaints involving dicamba in Arkansas.\u00a0 At one point mid-growing season, drift complaints were so severe that Arkansas banned the further use of dicamba during the growing season.\u00a0 In June, Missouri initially imposed bans, but withdrew those in favor of imposing additional restrictions on application.\u00a0 Tennessee also imposed additional restirctions in June.\u00a0 The issue of drift damage is particularly concerning for sensitive crops such as soybeans, wine grapes, or vegetable produce.<\/p>\n

According to Texas Farm Bureau, however, there have been only a handful of dicamba-related drift claims reported in 2016 and 2017.<\/p>\n

Cause of Trouble<\/strong><\/p>\n

What is causing these drift issues remains to be seen. Certainly, a major difference between the new dicamba formulations versus the use of prior dicamba versions like Banvel or Clarity, is that the new products can be applied over the top of growing crops, not just at the pre-emergence stage.\u00a0 This means that if nothing else, there are more growing crops in neighboring fields and the sheer potential of damage to crops increases because more growing crops exist.<\/p>\n

There are a number of possibilities that could be contributing to the drift damage from dicamba, and likely it may be a combination of any or all of them causing the problems:<\/p>\n