We can think of mechanical damage as any damage sustained by a tree or plant caused by a physical force. You will more often see this happen to young or thin barked trees. Young trees’ bark is vulnerable to even the most incidental bumps by kids toys, cat claws, bicycles and those aren’t even the most common ones. The most common would be: string trimmers, lawn mowers, cars and staking paraphernalia
It can be so frustrating to go through all the trouble of selecting and planting a tree only to have it die because someone got too close to it with a string trimmer. People assume that because it is just a thin piece of plastic that it won’t be a big deal if it “bumps” into the tree a bit. That might be true if you are talking about an old thick barked ash tree where if the damage is to the outer bark it is not a problem but in thin barked trees the inner and outer bark are so close as to be almost the same thing. The inner bark is also known as the phloem and it is the food supply highway for all the transportation of nutrients between the leaves and the roots.
When a tree or plant’s phloem has been cut, torn or compressed to the amount of half its circumference it is called girdling. This can happen above or below ground but wherever it happens the symptoms most people recognize are going to be found in the canopy. These can include: irregular leaf sizes, scorching, early fall color, canopy thinning, dieback and death. There have been many times I have been called to look at a tree that the homeowner was convinced had some disease only to find that it had been girdled by an old staking wire that was never removed or the neighbor boy with his lawn mower.
The good news is that there is an easy way to help prevent mechanical damage from happening. That is to create a buffer zone between thin barked trees and any lawn/ shrub maintenance equipment, aka put in mulch rings. Do not mound mulch around the base as that will rot out the bark and cause the same issue we are trying to prevent. Mulch is best when it is tapered away from the trunk to an ideal depth of about three inches.
If you have a question about what you are seeing in your trees or would like to have a free estimate please feel free to give us a call at (208)523-5296.