NAAA eNewsletter - 06/29/2017

On June 23, the Arkansas State Plant Board passed an emergency rule that would ban the in-crop sales and use of dicamba. The only exemption from this ban is for applications to pastureland. This ban technically only impacts Engenia, which was the only new formulation of dicamba approved for over the top applications of dicamba tolerant crops in Arkansas in 2017. The board also voted to expedite the rule that increases the penalties for illegal applications of dicamba. Following the vote, the proposed emergency rule will be reviewed by Arkansas Gov. Asa Hutchinson. From there, it will be submitted to the Executive Subcommittee of the Arkansas Legislative Council for approval.

The vote also expedited the enactment of new, higher fines for illegal dicamba usage. These fines could be up to $25,000 for “egregious” violations of Arkansas’ dicamba regulations. These new fines are set to take effect on Aug. 1, 2017. The plant board’s vote on June 23 puts the new penalty system into effect on Aug. 2. The current maximum fine for illegal applications is $1,000.

The pending emergency ban applies only to Arkansas and would last 120 days. Debate over the ban has pitted members of the agricultural community against each other, as those who have suffered from dicamba drift damage oppose the use of the new technology, making them at odds with those who have invested in it in the hopes of controlling weeds that have become resistant to other types of herbicide. In particular, glyphosate and PPO resistant pigweed is a serious problem. Many growers hoped that the new dicamba technology was the solution they were looking for to control these resistant weeds.

As a bit of background, there has been a long series of events that have led to this current situation. It began in the 1990s with the introduction and subsequent widespread use of glyphosate tolerant crops. As use of this technology increased, more and more weeds became resistant to glyphosate and spread throughout the country. In response to this growing problem, several companies began to develop crops that were tolerant to dicamba and 2,4-D, two popular herbicides that have long been used in agriculture. These new dicamba tolerant crops would allow direct applications of dicamba to them, providing another tool in controlling weeds, especially those that had become resistant to glyphosate and other types of herbicides.

The recent dicamba drift incidents began in Arkansas and Missouri in 2015, when dicamba tolerant cotton seed became available to growers. While the cotton was tolerant to the dicamba herbicide, no formulations of dicamba were yet labeled for in-crop, or over the top, applications to the cotton. To control resistant weeds, several growers made the decision to make illegal applications of older formulations of dicamba that are more prone to vapor drift. There were several incidents were the dicamba drifted and caused injury to soybeans. Soybeans are extremely sensitive to dicamba, and even minute quantities can cause symptoms.

In 2016, dicamba tolerant soybeans became available, but there was still no formulation of dicamba that could be legally applied over the top to these crops. Intense resistant weed pressure resulted in even more illegal applications of dicamba and a further increase in drift complaints. A dispute between growers over dicamba drift resulted in a murder occurring.

At the end of 2016, the new formulations of dicamba designed to be more resistant to volatilization were approved for use in 2017. These included XtendiMax from Monsanto, FeXapan from DuPont, and Engenia from BASF. None of these products received an aerial label to apply over the top of dicamba tolerant crops. The main Engenia label does allow aerial applications, but not to dicamba tolerant cotton or soybeans. The only legal way to apply Engenia or the other new formulations of dicamba over the top to dicamba tolerant crops is by ground.

Of the two formulations, only Engenia was approved for use in Arkansas due to an earlier Plant Board decision. All other forms of dicamba were illegal to use after April 15, making Engenia the only option for over the top applications to dicamba tolerant cotton and soybean in Arkansas. It was hoped that the new formulations with reduced volatility, strict label requirements for application, and intensive education efforts would reduce the number of drift complaints. Unfortunately, that has not occurred. The proposed ban in 2017 is the result of 242 alleged dicamba misuse complaints from 19 counties as of June 23, when the vote to approve the ban was taken. At the time this article was written on June 28, those numbers had increased to 420 complaints in 20 counties. There have been dicamba related drift complaints in Missouri, Tennessee and Mississippi as well, but not to the extent experienced in Arkansas.

Determining the exact cause of all the 2017 drift incidents will take time. One potential lead cause for many of the claims could be the continued use of the older, more volatile formulations of dicamba that are still illegal to use. At this time, no specific products have been identified for the 2017 misuse complaints. Another culprit could be failure to follow the label requirements, which have strict restrictions on nozzles, adjuvants, and weather conditions. The Engenia label limits applications to wind speeds below 15 mph and requires a downwind buffer zone of 110 feet for all applications. Arkansas passed even more restrictive parameters, limiting applications to wind speeds below 10 mph and requiring a 100-foot buffer on all sides of the application except for the downwind side, which requires a quarter-mile buffer zone if sensitive areas or crops are downwind. They also required applicators to complete certification training before making applications of Engenia.

As previously mentioned, aerial application cannot be used to make over the top applications of the new dicamba formulations to dicamba tolerant crops. That doesn’t mean there is not a valuable lesson to be learned from the current situation about the importance of pesticide stewardship and following the label.

The new herbicide technologies were hoped to provide some relief from the growing problem of controlling herbicide resistant weeds. When the EPA approved the new dicamba formulations in 2016, it made the registrations automatically expire in two years. This two-year expiration date allows the agency to decide whether to let the products expire permanently, or make changes to the registration requirements to address issues such as drift that arose during the first two years of the products registration.