Black farmers have filed a federal lawsuit against Bayer in an effort to stop the sale of Roundup, the weed killer it inherited with its $63 billion purchase of St. Louis-based Monsanto Co. in 2018. “The cycle can only be broken by removing the product from the market,” said Chris Schnieders, a partner in the Kansas City office of Napoli Shkolnik and one of the attorneys who filed the suit.