The Environmental Protection Agency announced late Monday, June 8, it has issued a cancellation order for three dicamba herbicides, but it will allow farmers to continue using some existing stocks of the products through July 31.

The order follows a June 3 ruling by the Ninth Circuit Court of Appeals vacating registrations for XtendiMax, Engenia and Fexapan. Another product, Tavium, which is a mixture of Dicamba and S-metolachlor, was not included in the ruling and can still be used.

Dicamba use as a post-emergence herbicide has been controversial because the product sometimes can volatilize and drift from a field planted with dicamba-resistant soybeans to neighboring fields of beans without the resistance trait or to other crops susceptible to dicamba. In its decision, the Ninth Circuit Court of Appeals said the EPA and registrants knew the chemical could cause such drift.

The court 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. After the decision, several states, including North Dakota, Nebraska, Minnesota, Iowa and Wisconsin, had decided to continue allowing farmers to use the products under state policies for this growing season.

South Dakota had decided to immediately prohibit sales and use of the three dicamba products, but South Dakota State University Extension Weed Science Coordinator Paul Johnson said the EPA's order will allow growers and applicators to use product in their possession as of June 3, including products for which they prepaid.

"So if a farmer has chemical at home he has already bought, he is fine," Johnson said. "He can spray it out."

However, he said there was very little product in the supply channel, so EPA’s decision may not be much help for farmers with dicamba beans. Johnson said the options farmers have left are to use Roundup, Tavium if they can find it, or another conventional herbicide. He does warn against using generic dicamba.

Johnson said the states with emergency exemptions issued in the last few days will also have to follow the EPA order.

The Monday EPA decision was a shock to the industry, which had suggested to EPA that it should appeal the court ruling. However, Bayer, which produces XtendiMax, said it welcomes "the EPA's swift action," calling the dicamba products "vital tools that many growers rely on to safely, successfully and sustainably protect their crops from weeds." The company said it is reviewing the EPA's action.

"Bayer stands fully behind XtendiMax, and we will continue working with the EPA, growers, academics and others to provide long-term access to this important tool," a company statement said.