--- title: Mower and String-Trimmer Damage: The Quiet Young-Tree Killer url: https://battleborntreeservice.com/guides/mower-and-trimmer-damage-to-trees/ business: Battle Born Tree Service address: 6301 US Highway 50 East, Carson City, NV 89701 phone: 775.232.8243 hours: Office Monday-Friday 8:30 am-5:00 pm; phones answered seven days a week; 24-hour emergency service credentials: ISA Certified Arborist WE-11728A on staff; Nevada Business License # 20131580674; fully insured type: Tree service (removal, crane work, pruning, stump grinding, defensible space, snow removal, firewood) --- - [Home](https://battleborntreeservice.com/) - [The Field Guide](https://battleborntreeservice.com/guides/) - Mower and string-trimmer damage: the quiet young-tree killer # Mower and string-trimmer damage: the quiet young-tree killer Mowers and string trimmers wound the bark at the base of young trees, and a wound that goes all the way around the trunk can kill the tree. The simplest protection is a mulch ring that keeps turf and equipment away from the trunk. Key takeaways - The ISA lists trees badly damaged by lawn mowers or string trimmers as a conflict between trees and turf. - Bark protects the living tissue under it. Repeated wounds near the soil line weaken the trunk and let decay in. - A mulch ring 2 to 4 inches deep, kept off the trunk, reduces the chance of trimmer and mower damage. - There are no cover-ups: wound dressings are not recommended. Nobody sets out to hurt a tree. A trimmer touches the bark for a second on each pass, and over a summer those touches add up. ## What does a trimmer do to a tree? The ISA's trees and turf brochure lists trees badly damaged by lawn mowers or string trimmers when turf is too close to the trunk as one of the conflicts between trees and grass. Bark is the tree's skin. The living tissue just beneath it moves water and sugars, and a wound there interrupts the flow. Our glossary entry on the [cambium](https://battleborntreeservice.com/glossary/cambium/) explains the layer. The ISA's risk brochure lists wounds from other human activity among the defects that cause trees to fail, and says they may be the result of construction, grade changes, compaction or poor pruning. Equipment strikes at the base fall in the same category. ## Why is it so easy to miss? Damage is low, often hidden under grass and rarely noticed until the leaves look wrong or the bark opens. A tree wounded on one side may seem fine for years. Look at the base of each young tree this week. ## How does a mulch ring help? The ISA lists reduced likelihood of tree damage from string trimmers and mowers among the benefits of mulch. It recommends 2 to 4 inches of organic mulch over the soil beneath the drip line as its preferred alternative to turf around a tree, and says turf out-competes young trees for water and nutrients. The ring also holds soil moisture and reduces weeds. The ISA warns against piling mulch against the trunk. Pull it back a few inches so the root flare stays visible. In fire areas, the Living With Fire guide asks for no wood mulch in the first 5 feet next to a house and thin layers in the next zone, so use rock or bare ground there. ## What if the tree is already wounded? Stop the cause first: keep equipment away. The ISA says most experts recommend not using wound dressings. Have an arborist look at the tree. A tree wounded around most of its circumference may not recover, and one with a partial wound may be fine. The ISA's mature care brochure says to report abnormalities to a local tree care professional. We prune young trees for structure and remove trees that cannot be saved. See [young trees in new subdivisions](https://battleborntreeservice.com/guides/young-tree-care-new-subdivisions/) and call [775.232.8243](tel:775.232.8243) for a free estimate. ## What else protects young trees? Keep sprinklers from soaking the trunk, avoid staking too tight, and teach whoever mows where the ring is. If an HOA or landscaper handles your lawn, send them a note. Use hand tools or a trimmer guard near the trunk. ### Sources - [International Society of Arboriculture, Trees Are Good: Trees and Turf (brochure)](https://www.treesaregood.org/Portals/0/siteContent/pdf/Web%20TAG%20brochures/TAG_CBweb_Trees%20and%20Turf_v2.pdf) (read October 17, 2026) - [International Society of Arboriculture, Trees Are Good: Proper Mulching Techniques (brochure)](https://www.treesaregood.org/Portals/0/siteContent/pdf/Web%20TAG%20brochures/TAG_CBweb_Proper%20Mulch%20Tech_v2.pdf) (read October 17, 2026) - [International Society of Arboriculture, Trees Are Good: Recognizing Tree Risk (brochure)](https://www.treesaregood.org/Portals/0/TreesAreGood_Recognizing%20Tree%20Risk_0721.pdf) (read October 17, 2026) - [International Society of Arboriculture, Trees Are Good: Pruning Young Trees (brochure)](https://www.treesaregood.org/Portals/0/TreesAreGood_Pruning%20Young%20Trees_0621.pdf) (read October 17, 2026) ### Talk to the office [775.232.8243](tel:775.232.8243) | Monday to Friday | 8:30 am - 5:00 pm | |---|---| | Saturday and Sunday | Office closed, phones answered | Phones answered seven days a week. 24-hour emergency service. [Free estimate](#quote) ### Keep reading - [Young trees in new subdivisions: the first ten years](https://battleborntreeservice.com/guides/young-tree-care-new-subdivisions/) - [Taking out a lawn without killing the trees](https://battleborntreeservice.com/guides/lawn-conversion-and-trees/) - [Watering mature trees in the high desert](https://battleborntreeservice.com/guides/watering-mature-trees-high-desert/) - [Root and trunk decay](https://battleborntreeservice.com/tree-guide/root-and-trunk-decay/) - [Cambium](https://battleborntreeservice.com/glossary/cambium/) - [Tree trimming and pruning](https://battleborntreeservice.com/tree-services/tree-trimming-pruning/) ### Terms on this page [Cambium](https://battleborntreeservice.com/glossary/cambium/) [Drip line](https://battleborntreeservice.com/glossary/drip-line/) [Root flare](https://battleborntreeservice.com/glossary/root-flare/) [Arborist](https://battleborntreeservice.com/glossary/arborist/) [The full glossary](https://battleborntreeservice.com/glossary/) ## More from the blog Pruning and care October 17, 2026 5 min read ### What should you do with your trees in October in Carson City and Reno? In October, finish watering while the ground is open, look over your trees for dead or hanging limbs, and clear leaves and needles away from the house. Save most live-wood pruning for the dormant seas Pruning and care October 17, 2026 6 min read ### Young trees in new subdivisions: the first ten years A young tree in a new subdivision needs very little pruning in its first two or three years, then steady structural pruning to build one strong central trunk and well-spaced branches. The ISA says tre Removal and equipment October 17, 2026 6 min read ### Where tree debris and green waste go in Reno and Carson City Green waste has a few legitimate homes in our area: the landfill or transfer station if the load is only wood and green waste, a fire district drop-off day or curbside chipping program if you qualify, [All posts](https://battleborntreeservice.com/blog/) ## Questions people ask Still have a question? Call [775.232.8243](tel:775.232.8243). Phones are answered seven days a week. ### Can I paint the wound? The ISA says wound dressings do not reduce decay or speed up wound closure, and most experts recommend against them. ### How wide should the mulch ring be? The ISA recommends mulch over the soil beneath the drip line where possible. For a small young tree, start with a ring several feet across. ### Does mowing right up to the trunk hurt? Yes, it can. The ISA lists mower damage as a tree and turf conflict. ### Will you fix the tree? We can look at it and tell you if it can be saved, pruned or has to come out.