ATLANTA — Pittsburgh right-hander Charlie Morton, who leads the majors in losses, was placed on the 15-day disabled list with shoulder fatigue Friday.

Manager John Russell said Morton also may need a mental rest. Russell said Morton would head to the Bradenton, Fla., for his rehabilitation.

Russell said Morton's arm likely was overworked from numerous side sessions as the right-hander sought better results. The 26-year-old Morton, who began his career with the Braves, is 1-9 with a 9.35 ERA in 10 starts. His nine losses and 45 earned runs allowed lead the majors.