Although trees can usually take care of themselves in rural forests, in urban environments such as your yard or community, trees need protection and appropriate care. These persistent and insidious myths cause many costly and dangerous mistakes in tree care every year.
Myth: Trees Have Deep Roots
Most trees begin life with a taproot – a straight tapering root that grows vertically down and from which other roots sprout. Over time, the roots will reach very deep into the earth and remain mostly vertical.
Most trees do not have a taproot; they tend to be more shallow-rooted than you might think. While some trees do have a taproot when they are saplings, after a few years the main root system changes to a widespread system with mainly horizontally growing surface roots and only a few vertical, deep anchoring roots.
Tree roots have to be shallow to stay within the loose, oxygenated soil near the surface. They are extensive, spreading to several times the width of the canopy. Damage to roots is a major cause of decline, death, or physical failure. Roots are injured or destroyed by soil compaction, soil removal, severed roots, fill soil over roots, flooding, or drought.
Myth: Tree Wounds Must Be Dressed
Like animals, trees can be wounded. Dressing the wound by painting over it or stuffing a cavity with material will speed and complete the healing process.
Unlike animals, trees have no wound-healing process. Healing means to restore to a previous healthy state, to repair or replace injured tissues. Trees, with their rigid cell walls, are unable to heal injured or infected tissue. Trees seal off damaged tissue rather than heal it. When tree bark is damaged, as in this picture, microbes attack the plant tissue, and trees respond by creating walls around the tissue. This process is called “compartmentalization,” and it occurs as the tree builds four walls around the injured area in order to preserve the rest of the tree. How well the tree ultimately survives the wound will depend on how successful the tree is at compartmentalizing the damage.
Research shows that wound dressings do not stop decay or stall rot. Trees respond effectively to their wounds without the aid of additional chemicals. Do not interfere with this natural process by applying house paints, wood preservatives, or heavy coats of any material to a tree wound. Keep your tree healthy, and it will take care of its wounds. In a short time, the wound surface will blend perfectly with the tree bark.
Myth: Prune Branches Flush With the Trunk
Pruning is often done to remove dead wood from a tree, to provide ground clearance, and to thin the crown for air circulation or to balance weight. To make sure there aren't any ugly stumps left on your tree, clip the branch as close to the trunk as possible.
The branch collar, which is the part of the branch that meets the trunk, must remain intact for the tree to remain healthy. Cutting a branch flush with the trunk removes the collar, which leaves the tree open to pests, decay, and disease. Learn more about pruning here.
Myth: Topping Is the Right Choice
When a tree becomes too tall, it's appropriate to remove all of the highest branches in order to make sure the tree doesn't interfere with the view, sunlight, or surrounding structures.
This practice, known as "topping," is completely unacceptable. It violates all accepted pruning practices. A topped tree is weak and deprived of nutrients from its leaves, which leads to weak branches, pests, decay, and disease. Not only that, but it is also expensive to maintain and visually offensive - ugly, bushy, weakly attached branches typically grow back even taller than the original limbs and may break or fall with little or no cause. Topped trees often need to be removed because they become hazardous.
Whenever topping is being considered, there are two acceptable alternatives: