Renowned acts include The Avett Brothers, Greensky Bluegrass, and more MILL SPRING—A celebration of bluegrass roots and forward-looking Americana will once again take center stage Labor Day weekend as the Earl Scruggs Music Festival returns to Tryon International from September 4 through September 6. Now in its fifth year, the festival honors three-finger banjo pioneer Earl Scruggs with a lineup that bridges generations of American roots music…