- Myth, topping is an effective way to reduce the crown of a tree for aesthetics and powerline clearance.
Fact, Topping a tree creates a dangerous tree. Topping is cutting branches or stems to random lengths. Trees should never be topped. Topping creates hazardous trees because the wood inside the cut branch begins to decay. The sprouts which grow in response to topping are not well secured to the topped branch and they can easily split from the tree as they grow larger. To avoid this, always prune a branch back to a living branch crotch. This technique is called drop crotching. - Myth, flush cutting is the proper way to prune a tree.
Fact, Never cut a branch flush with the trunk. That is, never make a flush cut. It has been standard practice to prune a branch flush with the trunk. Extensive research has shown that this practice injures the trunk and is extremely detrimental to tree health and shortens the life of trees. Flush cuts make a tree more susceptible to frost cracks, heat injury, root problems, cankers and sprouting. To avoid this, always cut to the outside of the branch collar which is located at the base of every branch. This collar is easily seen as a swelling where the branch meets the trunk. When pruning in this manner it may appear as though a stub is left on the trunk; however, properly done, this technique removes all of the branch and does not injure the trunk. - Myth, spray paint is an effective way to seal off a pruning cut.
Fact, Wound dressings and pruning paints do not prevent wood rot. Wound dressings do not prevent wood decay behind a pruning cut. They provide no benefit to the tree. Some research indicates that wound dressings promote decay in certain situations. If pruning paints or wound dressings are to be used for cosmetic purposes, apply only a very thin coat. Only proper pruning practices prevent wood rot.
- Myth, roots do not grow beyond the drip line.
Fact, Roots grow far beyond the edge of the branches. Trees growing in the woods have root systems reaching well beyond the edge of the branches. Frequently, roots extend from the trunk as far as the tree is tall. Roots on trees and shrubs planted in a landscape grow to 3 times the branch spread within 2 or 3 years after planting. - Myth, grading the soil on one side of the tree is acceptable, as long as no work is done on the opposite side.
Fact, Damaging roots on one side of a tree may cause branch dieback on that side only, or at random throughout the crown. Roots on one side of trees such as oaks and mahogany generally supply the same side of the crown with water and nutrients absorbed through the roots. When roots on one side of a tree are injured, branches on that side often will drop leaves. On other trees such as the maples and rosewood, damage on one side of the root system may cause branch death anywhere in the crown of the tree.
- Myth, running a bulldozer to clear land, will not damage trees chosen to remain.
Fact, Most roots are in the top 3 of soil. The finer roots are concentrated in the top several inches of soil. Most tree roots are located within the top 3' of soil. However, because the majority of the fine roots are concentrated in the top several inches of soil, minor soil disturbances can injure or remove a large portion of the absorbing roots on a tree. This often happens in landscapes surrounding recently constructed building.
- Myth, Cuts in tree trunks caused by dozer blades or tractor buckets, will not harm the tree.
Fact, A small trunk wound inflicted by heavy equipment during construction or at any other time can cause major injury to the tree. Trees cannot replace injured tissue (heal) like animals, therefore injury permanently reduces the trees capacity to fight future stress caused by insects, disease or other factors. In addition, many roots are destroyed as heavy equipment operates over the root system. Even one pass over the root system with a bulldozer, earth scraper or other piece of heavy equipment can cause significant root damage. Do not allow equipment to operate within the dripline of trees which are to be saved. - To save a tree during construction, do not disturb soil beneath the branch dripline. Tree roots extend to 3 or more times the dripline of the tree. Approximately 50% of the root system is located outside of the dripline. No equipment should operate within this area if the tree is to be saved. Sturdy fences should be constructed at the dripline to encourage enforcement of this guideline. This serves as the best guide to helping prevent construction related tree decline.
- Grading to prepare a site for laying sod or planting shrubs can harm trees. Since many of the fine roots are located close to the soil surface, changing the soil grade by as little as 6 inches can cause extensive damage to the root system of existing trees. Design the landscape to largely fit the existing grade. If grade changes are necessary close to a tree, remove the tree and plant several younger, healthy trees.
- If a tree survives the first 2-4 years following construction, it may still die from construction related injuries. Trees frequently decline after construction of a building. Often, branches begin dying within a year or two due to severe root damage. The tree may be dead within 3 or 4 years. However, it is not uncommon for trees to show a slow decline over a 5 to 15-year period. The tree may not show obvious signs of decline for many years, but, following a drought period branches may quickly loose leaves and begin a rapid decline. The tree may be dead a year or two later.
- Trees do not heal, but they are capable of isolating injured tissue from healthy wood. Trees are not like people because they do not heal. They lose the storage capacity and function of injured tissue forever because cells cannot be replaced. In contrast, animals heal by replacing injured tissues. Plants must seal off the injured tissue from the healthy portion of the plant in order to stay alive. The swollen callus tissue developing around a trunk wound or pruning scar is closing over the injured tissue, not healing.