Errant lawn mowers and string trimmers are wounding trees all over the residential landscape. As people mow and trim lawns, many inadvertently create damage that could eventually kill trees. These wounds often become large unsightly scars that impact the overall health and vigor of the trees. There are simple solutions that can be implemented to ensure trees will not succumb to lawn-mower disease or trimmer syndrome.
Even a gentle encounter with a lawn mower can cause bark to slip off during the spring when heavy sap flow occurs and trunk expansion is greatest. Lawn mowers also damage trees by cutting into exposed surface roots. String trimmers can slowly rip bark off until the strings begin to damage the tissue below the bark.
The living layer of the tree, the cambium, lies just below the bark and is the place where growth originates. The xylem and phloem are on either side of the cambium, and, if they are damaged will no longer transport water and other materials up and down the tree. Part of the tree may die, or if the wound is mostly or all the way around the tree, the whole tree can die.
There are two simple solutions to the problem. First, install a tree ring with mulch or rocks around the base of the tree to keep lawn-mowing equipment from damaging the tree. If you must have turf growing right up to the base of the tree, use a hand shear to trim the grass there. Use a trimmer around hardscapes such as brick edges, concrete walkways, block retaining walls and steel edging.
If damage already has occurred to a tree, remove any dead bark. A razor blade or chisel with a rubber mallet can be used to remove loose bark. If there is damage to any portion of the trunk in contact with the soil, the wound will not seal over because of the activity of soil microorganisms. Remove any soil or mulch that is near the wound.
Root damage also can occur during lawn mowing. The best solution is to put about a ¼ inch of good topsoil next to roots and slowly raise the grade each spring and fall up and over the exposed roots. The grass will grow right through the topsoil each spring and fall.
Professional lawn mowing companies should be aware of the possibility of damaging your trees, and should be held accountable for any damage that results from gas- or electric-
powered lawn equipment. If trees are being damaged, the company should be made aware of the problem and should correct it. If your trees are killed or damaged beyond repair, the trees should be replaced. It is always a smart idea to make sure any company you deal with provides proof of its general liability insurance in the form of an insurance binder.
Robert Brudenell is a certified master arborist and owner of The Natural Way Inc. Send questions to robert@thenaturalwayinc.net.
