Trees are wonderful additions to the landscape. For a tree to survive, it must extend its roots throughout the yard. Unfortunately, some of the roots may burst through the surface, ruining the yard or garden. Some trees such as willow and poplar are more prone to surface roots, while others may extend their roots in search of water. Be aware that killing some roots may greatly damage the tree. If you've removed the tree, you can kill the roots without prejudice.
Mix a non-selective herbicide according to the instructions on the label. Failure to mix the herbicides according to the instructions is dangerous and often illegal.
Spray the exposed root with the herbicide on a day with good weather. Do not spray when there are heavy winds or rain.
Cut the dead root from the ground, using a shovel to sever the root. Dig up the root area to remove the root from the dirt.
Place synthetic burlap over the exposed roots to kill them if the herbicide doesn't work.