Another way to prevent weedeater damage on young trees is to use trunk guards that fit around the base of the tree. A trunk guard is a flexible plastic or vinyl tubing, approximately 1 foot tall, that will expand with the growth of the tree. They will expand up to approximately 4 inches in diameter.
This is good to protect the tree from gardeners who are careless or even accidentally allow the weedeater string to slap the trunk of the tree. The trunk guard can protect the bark and cambium layer of your tree from damage by the weedeater string.