Weather, animals, and people cause mechanical injury to plants. Most of this damage is caused by people and the improper use of lawn equipment around the plant. If a lawnmower or lawn trimmer touches the bark, it can cause damage to the bark and vascular system of the tree. By injuring the bark, the tree diverts energy from other systems such as branch and leaf development to healing the wound. By damaging the vascular system, the plant becomes less effective in the movement of water and sugar, which is vital to its health. As a result, these plants have a tendency to decline or eventually die.

Roots can also be affected by mechanical injury. Soil compaction occurs because of increased foot traffic and decreases the amount of oxygen available to the root structure. Bad weather can also cause mechanical injury. Large amounts of ice and snow can build up during a severe winter and can cause branches to break. Lightning strikes can also damage or kill a tree. Lightning causes massive damage to the vascular and structural tissues, killing the tree or making it structurally unsafe.

Preventing Mechanical Injury

Step 1. Use mulch around the base of the tree or shrub to aid in protecting the roots, trunk and branches. Three inches of mulch is sufficient. Do not use white rock or other reflective material as this has the potential to scorch the bark.
Step 2. Proper pruning at the correct time of year will encourage the proper growth and create a stronger, more vigorous tree.
Step 3. Stake larger trees or shrubs until they become established. Ensure you remove these stakes the following year to prevent girdling problems.
Step 4. Location is important to prevent wind damage. Provide a windbreak, or choose a plant tolerant of high winds.
Step 5. (Optional) Install a lightning protection system for taller, more valuable trees. Contact a tree service company for more information on this.
Step 6. Use caution when cutting or landscaping around trees and shrubs not to damage the bark and vascular system.

For more information, call the professionals at Ace of Blades at 818-LAWN (818-5296),
or e-mail us at