St. Louis Cardinals rightfielder Larry Walker was placed on the 15-day disabled list Tuesday with a herniated disc. The move is retroactive to July 23. The 1997 National League MVP, Walker was put on the DL so he can rest after receiving a third cortisone shot in his neck. He has been bothered by a herniated disc the entire season. Walker, who missed the last two games of a weekend series versus the Chicago Cubs after a second cortisone shot, is batting .271 with 11 homers and 40 runs batted in through 73 games this season. In other team news, the Cardinals recalled infielder/outfielder John Gall from Triple-A Memphis.