The trial in the antitrust litigation stemming from allegations that mushroom farmers conspired to fix prices is set to begin May 20, and U.S. District Senior Judge Berle M. Schiller of the Eastern District of Pennsylvania plans to oversee the proceedings.

Schiller on Tuesday denied a request to step down from the case after one of the defendants demanded his recusal, alleging he had participated in ex parte communications with some of the parties engaged in settlement talks.