The 49ers placed Wishnowsky (back) on injured reserve Saturday, Matt Barrows of The Athletic reports.

A back injury will force Wishnowsky to miss at least the next four regular-season games, making Week 15 against the Rams on Thursday, Dec. 12 the earliest he can return. Pat O'Donnell will serve as the 49ers' punter with Wishnowsky sidelined.