Stressed tree from stem girdling root

The red maple on the right was planted at the same time as the red maple on the left but it is smaller. Both trees received mulch right up to the trunk. The stem girdling root on the right tree is shown below-right and is responsible for the smaller size. The larger tree on the left has no such defect. The portion of the girdling root that is embedded in the tree can not be removed, but the root can be cut to stop its growth. Sometimes girdling roots kill trees.