A method for controlling a braking mechanism for a supply roll with wrapping material for a round baler that passes through a first phase wherein, after detection of sufficient crop material in the baling chamber, wrapping material is brought up to the baling chamber and introduced into the baling chamber. The braking mechanism provides a higher braking force during the wrapping operation than the first phase. The wrapping operation is started on detection of movement in the wrapping material. This prevents the braking mechanism from being activated prematurely and leaves sufficient time to deactivate the braking mechanism after the wrapping operation.