Various embodiments related to a tree guard are disclosed. One embodiment provides an L shaped breakaway bracket for use with a modular tree guard assembly. The L shaped breakaway bracket includes a horizontal member extending substantially perpendicularly from a vertical member, wherein the vertical member is thinner and longer than the horizontal member. At least one fastener hole is provided in the horizontal member for receiving a fastener for securing the horizontal member to a rail. At least one fastener hole is provided in the vertical member for receiving a fastener for securing the vertical member to a post. The breakaway bracket is adapted to break along the intersection of the horizontal member and the vertical member and separate the rail from the post when a force that would otherwise be sufficient to deform the rail is applied to the rail.