A twine tensioning system for a baler in which adjacent lengths of upper and lower twine lengths are knotted and passed around a bale that is being compressed in a baler. Knots are formed to connect twine at the forward and rearward end of the bales. A slack arm maintains tension during the process of knotting and severing the twines and a stop bar is removably positioned to provide a lower stop for the slack arm when the bales are being passed through the system to minimize wear.