With more free time due to his cancellation in Bayreuth, Andris Nelsons will expand his commitment at Tanglewood next summer, leading ten programs with the Boston Symphony Orchestra over four weeks. He will open the Tanglewood season with Mahler’s Second Symphony on July 7, and lead the traditional closing program of Beethoven’s Ninth Symphony August 27. He will also lead the BSO’s first full-length concert performance of Wagner’s Das Rheingold on July 15.