Weather, animals, and people cause mechanical injury to plants. Of the 3 causes, damage by people is number 1. Most of this damage is caused by the improper use of lawn equipment around the plant. If a lawn mower or weed whacker hit the bark they can cause damage to the tree. By hitting the bark these machines cause damage to the bark as well as the vascular system. By damaging the vascular system you cause the plant to be less effective in the movement of water and sugar which are vital to the health of the plant. By injuring the bark you cause the tree to divert energy from other systems such as branch and leaf development to healing the wound. 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 the increased foot traffic. When soil compaction occurs it 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. Large accumulations of both of these can cause branches to break. Lightning strikes can also damage or kill a tree. Normally lightning will not knock a tree down, but causes massive damage to the vascular and structural tissues, killing the tree or making it structurally unsafe.

Solving the problem:

There are steps a homeowner can take to decrease the chances of mechanical injury occurring.

Step 1. Use mulch around the base of your tree or shrub to aid in protecting the roots, trunk and branches. 3 inches of mulch is sufficient to achieve this. 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 will encourage the growth of a stronger, more vigorous tree.

Step 3. Stake larger trees or shrubs until they become established. Ensure you remove these stakes in the second year to prevent girdling problems in later years

Step 4. Site location is important to prevent damage from wind. If you choose an area that is exposed to wind ensure you use a plant that can tolerate high winds. If you can, provide some sort of windbreak.

Step 5. Although not a big concern, you can install a lightning protection system for taller, more valuable trees. Contact a tree service company for more information on this.

Step 6. Take a little extra time when cutting or landscaping around your trees and shrubs. By being aware of the damage you can cause, you will lessen the chances of injuring your trees and shrubs.