Trees can slowly weaken and die over a period of years or decades because of trunk girdling due to girdling roots. Roots that begin to grow around the main stem of the tree continue to enlarge as the trunk expands, cutting off or restricting the movement of water, mineral elements, and stored food reserves. Girdling roots often develop when trees are planted too deeply, or mulch is continually piled high against the trunk. Over time, growth of the branches on the side of the plant affected by the girdling will be slowed. As injury progresses, leaves will become smaller and lighter green, fewer leaves will be produced, and eventually the affected branches will begin to die back. Death of the entire plant can occur in five to 20 years; watering, fertilizing, and pruning will do little to correct the problem.
Girdling roots can be suspected if the trunk of the tree lacks flaring buttress roots. Girdling roots can often be discovered by digging into the top few inches of soil on the side of the tree lacking a root flare. Use of an air knife or air spade by a professional arborist can reveal such roots without injuring them. If girdling roots are found, the girdling root must be removed (a process normally carried out with a chisel).
Conducting a preventative inspection when the tree is about six inches in diameter will assist in correcting the problem before it becomes serious. If the inspection reveals girdling and a considerable amount of damage, the most prudent action may be to replace the tree. Spending money on a weakened tree which subsequently dies can be an extremely frustrating experience; because correction of this problem is so labor intensive, the costs and benefits should be weighed carefully prior to making any decisions. Removing a girdling root creates a wound, and if the wound is extensive, further problems could develop. However, if nothing is done, the girdled tree will likely decline further and die.
