A federal judge overseeing about 900 lawsuits that allege Bayer’s Roundup weed killer caused cancer has appointed Kenneth R. Feinberg, a lawyer known for helping to resolve high-stakes litigation, to mediate settlement talks.

Mr. Feinberg has been instructed to meet with lawyers for Bayer and plaintiffs within 14 days, Judge Vince Chhabria of United States District Court in San Francisco said at a hearing on Wednesday. Judge Chhabria, who ordered confidential mediation on April 11, appointed Mr. Feinberg after the parties failed to agree on a mediator.

Mr. Feinberg has led mediation talks over the September 11th Victim Compensation Fund, the BP Deepwater Horizon oil spill, Volkswagen’s diesel emissions scandal and General Motors ignition switch litigation.

More than 13,400 plaintiffs allege that Roundup, which contains glyphosate, causes non-Hodgkin’s lymphoma and that the manufacturer failed to warn about that risk. Most of the lawsuits are pending in state courts.