A knot stretcher for use in tightening splice knots that connect twine balls on an agricultural baler. The knot stretcher includes a pair of pulling bars connected at pulling bar pivot at one end of each of the pulling bars, and a pair of levers, where one of the pair of levers is attached in a middle section of its respective pulling bar. Each lever has a handle portion at one end and an arm portion extending from an elbow formed in the lever. Each lever attaches to its respective pulling bar with a fixed pivot located near the elbow and distal ends of the arm portions of the two levers are attached at a moving pivot. The knot stretcher has clamping jaws positioned on the pulling bars to securely clamp a respective one of the twine tails of the splice knot that is to be tightened.