Lawn mower blight is a tree injury sustained from repeated hits from a lawnmower blade or weed whacker string. Trees afflicted with lawn mower blight are more prone to diseases and may have shorter lives.
What causes lawn mower blight?
Mowing too close to a tree or using a string trimmer close to a tree can cause lawn mower blight. The wickedly fast rotations of mower blades or trimmer line can wound the bark on the tree’s trunk, which becomes an opening into the tree.
Running a mower over a tree’s exposed roots also can cause lawn mower blight.
Young trees are the most vulnerable to lawn mower blight as their bark is still thin and tender. A young tree’s bark can be bruised or torn off completely.
Older trees are not immune to lawn mower blight. Travis Cleveland, an extension specialist with the University of Illinois Urbana-Champaign Extension, says that while the thicker bark of older trees offers better protection, they can still be injured. “The edge of a steel mower deck can still cut through the tree bark,” he says.
Lawn mower blight that extends around the whole base of the tree girdles it. Girdling often happens when a string trimmer is used to cut weeds at the base of a tree.
How does lawn mower blight weaken trees?
The openings in the bark caused by lawn mower blight indirectly weaken and kill trees. These openings are entry points for diseases and insects that can cause further injury to the tree. The worst scenario is that wood-rotting organisms get into the tree and start rotting it.
But how does lawn mower blight weaken and kill trees directly? The damage to the bark often extends into tissues inside the tree that are responsible for transporting sap, which has nutrients and water the tree needs to grow. The site of lawn mower blight can become a dead end that sap will have difficulty passing through.
“The outer bark and inner bark (phloem) would be the first layers injured. The cambium is a thin layer between the phloem and the xylem (sapwood). Any injury to these tissues disrupts their functions and affects growth,” Cleveland explains. The phloem and xylem transport food and water, respectively, while the cambium is responsible for new growth.
A small wound isn’t the end of the world for the tree. “If 25% or less of the bark around the trunk has been damaged, the tree will likely recover, though it may show some stress,” says Cleveland.
The worst-case scenario is when the tree becomes girdled. A tree with damage all around the base of its trunk can’t get the nutrients it needs and will die. You will need to remove dead trees for your own safety.
FAQs about lawn mower blight
Can you fix lawn mower blight?
There’s not much that you as a homeowner can do to fix lawn mower blight.
In some cases, lawn mower blight can partially heal as the tree will try to seal the wound. “This can take many years and isn’t as protective as the trees’ normal bark growth,” says Cleveland, the extension specialist.
It’s better to think of lawn mower blight as permanent because the tree won’t be the same, even after many years.
How do you prevent lawn mower blight?
There are a few ways to prevent lawn mower blight:
- Create a weed-free area around the tree with mulch, gravel, or groundcover.
- Protect the trunk with a cage or plastic pipe.
- Hand-pull or use garden shears to cut grass and weeds around the tree.
Does lawn mower blight spread to other trees?
Lawn mower blight doesn’t spread to other trees. “In plant pathology, ‘Blight’ is a term often used to describe the symptoms of an infectious plant disease,” says Cleveland, the extension specialist. “The injury resulting from a mower can cause a tree to appear sick or diseased. However, mower damage is a mechanical injury and is non-infectious.”
Hire a pro to carefully maintain your lawn
Lawn mower blight can lead to the death of your beloved trees. When they die, you’d lose not just shade and aesthetics but also money as you’ll need to have a professional remove the tree from your property.
If you’re worried about injuring your trees while you’re caring for your lawn, why not hire a pro to do it for you? Lawn Love’s pros have the skills, knowledge, and experience to mow your lawn and remove weeds with the utmost care. If you’re still worried, our pros can also mulch around your trees to help prevent mower blight. Hire a Lawn Love pro to maintain your landscape today.
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