Scruggs died of respiratory problems at Nashville's Baptist Hospital Thursday, the Tennessean reported.
Scruggs helped incorporate bluegrass into the folk music boom of the 1950s and 1960s and helped turn the genre into a money-making business, the newspaper said.
Dwight Yoakam told the newspaper: "One of the loudest sounds ever in country music just silently left. She didn't take the curtain calls, but a lot of us would never have heard Flatt & Scruggs if it hadn't been for Louise Scruggs."
Louise Certain spotted her husband-to-be during a Grand Ole Opry show in 1946. Earl Scruggs had just joined Bill Monroe's Blue Grass Boys band.
Despite his obvious talent, she recalled she was "more struck by him, not his playing." The pair met after the show and married two years later.
She formed the Scruggs Talent Agency and got her husband on the bill of the first Newport Folk Festival in 1959, orchestrated live Flatt & Scruggs recordings at Carnegie Hall and Vanderbilt University and set the deals with TV's "The Beverly Hillbillies" and the big screen's "Bonnie and Clyde."
She is survived by her husband, Earl, as well as sons Gary and Randy.