Soybean and cotton farmers using dicamba are reeling after a federal judge revoked the national permit for the popular herbicide.

It works for them because crops are genetically modified to resist the herbicide dicamba, and weeds in those fields are sprayed without harming the soybeans or cotton plants.

Deliveries of the weedkiller and the crop seeds engineered to withstand it were already being delivered to farms for the 2024 crop season when a federal judge barred its use in the United States last week.

Three manufacturers are also impacted by the court decision — Bayer, BASF, and Syngenta. The drift-prone dicamba pesticide has long been among their most popular and, at the same time, controversial projects.

Soybean and cotton farmers are turning to their associations, seeking help from the U.S. Environmental Protection Agency (EPA), which had issued the now-revoked permit.

Pesticide is the primary weapon in the war on weeds. For example, soybean farmers rely on post-emergent dicamba to manage yield-robbing weeds, which have the potential to destroy more than half of a crop’s yield and inflict more than $15 billion in damages to U.S. soybean crops if not controlled,  Some weed varieties, such as palmer amaranth, can exact catastrophic yield losses of nearly 80 percent without pesticide use.

The American Soybean Association and state soybean groups from about half the states were quick to write EPA Administrator Michael Regan as soon as the federal court ruling dropped. It’s up to Regan to decide whether to appeal or seek a stay of the order.

The Soybean associations called it a “deeply flawed order” and urged Regan to appeal the decision. The letter to EPA also points out that for the upcoming 2024 growing season, about 45 percent of acres planted in soybeans — more than 37 million acres — are expected. to be planted with soybean varieties of the pesticide.

The letter also urges the EPA to issue an “existing stocks” order to allow the use of “all volumes of low-volatility dicamba.”

The winning side plaintiffs in the court action were the National Family Farm Coalition, the Pesticide Action Network, the Center for Food Safety, and the Center for Biological Diversity. Legal counsel from the Center for Food Safety and Biological Diversity represents them.

The ruling was by the U.S. District Court of Arizona in Tucson. It overturned EPA’s 2020 approval of the pesticide, which included additional application restrictions that the plaintiffs argued failed to prevent the ongoing drift damage.

They claimed dicamba use is causing far-reaching harm and pointed to USDA’s estimates that as many as 15 million acres of soybeans were damaged by dicamba drift.