A large round baler is equipped with a device for wrapping a bale formed in the baling chamber of the baler with a web of plastic sheeting or net wrapping medium. A supply roll of the wrapping medium is located in a box mounted forward of the baling chamber for movement along a fore-and-aft extending guide rail between a standby position, wherein a free end of the wrapping medium is supported by a guide surface at a location spaced forward of the baling chamber, and a wrapping position, wherein the free end of the wrapping medium is located for being grabbed by rotating rollers and/or the formed bale so that a length of the wrapping medium is pulled from the supply roll as it is wrapped about the bale. A power operated brake operates on the supply roll so as to provide a constant tension in the wrapping medium during wrapping operation.