ST. LOUIS — The National Black Farmers Association filed on Wednesday a federal lawsuit to block Creve Coeur-based agribusiness giant Monsanto and its German parent company, Bayer, from selling the weedkiller Roundup.

The suit alleges that Black farmers across the country have been forced to use Roundup-resistant seeds and Roundup in increasingly heavier applications, and that Monsanto failed to inform the farmers of the weedkiller’s risks.

“The cycle can only be broken by removing the product from the market,” Chris Schnieders, a partner at Napoli & Shkolnik in Kansas City and one of the attorneys who filed suit, said at a Wednesday press conference.

In June, Bayer agreed to pay more than $10 billion to settle tens of thousands of claims that Roundup causes cancer, but wouldn’t agree to stop selling the product, or add warning labels.

Bayer said Wednesday’s suit is brought by two firms that refused to settle. “People should see this action for what it is — an attempt by plaintiffs’ lawyers to use media and more litigation to further their own financial interests,” the company said in a statement sent by deputy communications director Susan Luke. “There is no basis in fact or law for the health claims in this suit, as Roundup has been assessed and approved by independent health regulators worldwide, including the EPA, which have found that Roundup can be used safely as directed.”

Farmers have many seed and weedkiller choices, the company said. “Competition and choice are alive and well in agriculture and benefit farmers equally,” the statement concluded.

Bayer had hoped the June settlement would end a period of uncertainty that carried great risk for the company’s valuation and reputation. Over the past two years, for instance, two separate California juries ordered the company to pay plaintiffs $286 million and $2 billion, before judges and appeals courts trimmed the payments into the tens of millions of dollars.

But Wednesday’s new lawsuit signals that legal fights are keeping Bayer’s marquee weed control product in the crosshairs.

Jim Onder, an attorney from the St. Louis-based Onder Law Firm and a co-counsel for the suit, said there are at least 25,000 alleged cancer victims who have not settled with Bayer. Some of those are members of the National Black Farmers Association who sued Wednesday.

John Wesley Boyd Jr., the association’s founder and president, equated Bayer’s settlement offer to “pennies” at Wednesday’s press conference.

The organization represents 109,000 Black farmers in 42 states. Wednesday’s suit alleges that thousands of those farmers have used Roundup for decades. Some have already been injured by the product, the suit says. Others believe they are developing cancer.

The suit says Monsanto has slowly bought up seed companies and shelf space in local seed stores, “crowding out conventional varieties,” and practically requiring growers to adopt seeds that are genetically modified to withstand Roundup herbicide. An “overwhelming majority” of Black farmers, the suit says, use the product and are disproportionately affected by the risks associated with it.

“I don’t know a Black farmer that has not used the product,” Boyd said at the press conference. “That’s how big the issue is.”

Those farmers, he added, face compounded risks as members of groups that have historically been denied access to outreach and technical assistance about ways to best use the chemical. Black farmers, “due to long-documented disparities in literacy and education rates,” have been particularly hurt by the lack of a “plain, clear warning” on Roundup products, the suit alleges. And Monsanto has told them for decades that Roundup products are safe, the suit says.

Moreover, the weeds Roundup was meant to kill, pigweed and broadleaf species, are becoming more and more resistant to the herbicide, the suit says, requiring farmers to use more Roundup, and also other dangerous chemicals.

The suit asks the court to block Monsanto from continuing to market and sell Roundup, to force Monsanto to remove the products from store shelves, and to more clearly label the product’s dangers.

Ben Crump, a co-counsel for the Black farmers association, also represents the family of George Floyd, killed by a police officer in Minneapolis.

Bayer did not make an executive available for an interview, but said in its statement, “Racism has no place in our society or at Bayer.”