Two More Conductors Join the Injury Roster With two more conductors sidelined, here and in Europe, just weeks after Andris Nelsons and Christoph Eschenbach bowed out of Tanglewood performances, the classical music world is compiling an injury list that rivals Major League Baseball. James Conlon has withdrawn from engagements at Ravinia, the Chicago Symphony Orchestra's summer home, and in La Jolla, Calif., because he is having surgery to remove an inflamed section of his colon caused by diverticulitis. These include two performances of Britten's "Burning Fiery Furnace" at Ravinia, where Mr. Conlon is music director, both scheduled for Aug. 17, and a concert of Britten's orchestral music, with members of the Chicago Symphony Orchestra, at Trinity Episcopal Church in La Jolla on Aug. 23. The Ravinia concerts have been canceled. The Los Angeles Opera, which is presenting the La Jolla concert as a part of a Britten festival, has not announced whether Mr. Conlon (who is also the opera company's music director) would be replaced. Mr. Conlon's spokeswoman, Constance Shuman, said that Mr. Conlon's surgery required four weeks" recuperation time, and that he was expected to recover in time to conduct Britten's "Midsummer Night's Dream" at the Metropolitan Opera on Oct. 11. In Lucerne, meanwhile, Pierre Boulez, who is the artistic director of the Lucerne Festival Academy, has withdrawn from festival concerts on Sept. 7 and Sept. 9 because of a fractured shoulder. He is, however, expected to be present for the rehearsals, as well as for discussions that introduce the concerts (one of which includes a commissioned work by Dieter Ammann and a work by Mr. Boulez; the other includes music by Webern, Stravinsky and Bartok). The Spanish conductor Pablo Heras-Casado will lead those performances in Mr. Boulez's place.