States continue to grapple with how to handle the dicamba herbicide after a Ninth Circuit Court of Appeals decision that vacated labels approved by the Environmental Protection Agency for most formulations that are sprayed over growing soybeans.

Several states have decided to continue to allow spraying of dicamba formulations Xtendimax, FeXapan and Engenia for this season under state regulatory processes. South Dakota, however, broke with the pack on Monday, June 8, suspending all sales and applications of the three dicamba products until further guidance is provided by the EPA, which the South Dakota Department of Agriculture has requested.

The South Dakota decision runs counter to those of its neighbors in North Dakota, Nebraska, Minnesota, Iowa and Wisconsin. State officials in those states have decided to continue to allow the use of dicamba under state registrations until they receive further guidance from the EPA.

Dicamba has been controversial because of cases where the herbicide would sometimes drift from a field planted with dicamba-resistant soybeans to neighboring fields of susceptible beans and other non-target crops. The court said EPA and registrants knew the chemical could cause such drift.

The Ninth Circuit opinion came at a particularly bad time for northern soybean growers, as the peak spraying season has yet to begin. Cut-off dates for dicamba use in most of the states fall in late June. However, most farmers already had purchased or planted their seed, including dicamba-tolerant seed, and many had purchased dicamba.

“The Circuit Court of Appeals decision to revoke the use of these products was, unfortunately, very untimely for our farmers as many had already purchased the herbicide for this growing season,” said Minnesota Agriculture Commissioner Thom Petersen. “Timing is critical for farmers to apply the products and our further interpretation of Minnesota law allows us to use these products.”

Other options

Not all dicamba formulations were affected by the Ninth Circuit ruling. Tavium, a mixture of Dicamba and S-metolachlor, is still labeled for over the top use, however there are limited supplies available. South Dakota Extension lists a few additional options farmers can consider.

Conventional products like Flexstar, Ultra Blazer and Cobra are labeled for post application and are effective on waterhemp at 2-4 inches, but will have limited control on larger weeds. Furthermore, Cobra is effective on kochia at 1-2 inches. Producers should follow labels closely, as there are limited products available to control other broadleaf weeds.

And while generic dicamba may be available, SDSU Extension Weed Science Coordinator Paul O. Johnson does not recommend it.

“I caution farmers not to look at buying generic dicamba to spray on their soybeans just because they are still available for purchase,” said Johnson. “These products are illegal to use over the top on soybeans, and when this has happened in the past, it caused significantly more drift to non-target crops than the former labeled products."