The Packers announced the move with Tretter on Wednesday, one day before the season-opening game at Seattle. To take his place on the roster, the team promoted center Garth Gerhart from the practice squad.
Tretter, a fourth-round pick in 2013 out of Cornell, missed most of his rookie season with an ankle injury. He was groomed all offseason to take over at center and had a strong preseason, but he sustained a knee injury during the third preseason game against Oakland.
Players on IR-designated to return are sidelined for the first six weeks of the season. At that point, they can begin practicing, but they are not allowed to play until Week 9. For Green Bay, Week 9 is a bye. The Week 10 game is at home against Chicago on Nov. 9.
Gerhart (6-1, 310) entered the NFL as an undrafted free agent out of Arizona State in 2012. As a rookie, he spent training camp with Cleveland and the entire regular season on the Browns’ practice squad. When the Browns didn’t retain him at season’s end, he joined Green Bay’s practice squad for the 2012 playoffs. He competed for a roster spot in 2013 but was released. After a week on Carolina’s practice squad, Gerhart was released, only to wind up in Green Bay for the rest of the season.
Gerhart again competed for a roster spot in training camp this summer but was among the final cuts.
To fill Gerhart’s spot on the practice squad, Green Bay signed rookie guard Josh Allen. Allen (6-3, 312) started 42 games at Louisiana-Monroe, earning all-Sun Belt first-team honors as a senior. He spent training camp with Tampa Bay.