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Minot Park District

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Pruning 101

Pruning is the most common maintenace procedure for a tree, and is essential to developing a tree with strong structure and a desirable form. However, it is crucial to understand how to prune a tree correctly as to avoid damaging the tree, or worse, permenantly shortening it's life-span. In the sections below, a brief introduction of proper pruning techniques are given. Keep in mind, just as you would never try to fix your car without some knowledge of what you are doing, never prune a tree without first learning a little about the proper techniques!

Keep in Mind Before Pruning:
 Each cut could potentially change the growth of the tree. Therefore any branch should not be removed without a reason (i.e. to remove dead branches or crowding that prevents air/light penetration).
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 Removing more than 25% (one quarter) of the foliage on a tree at one time can be detrimental to the tree, resulting in reduced growth, starvation, and/or stress on the tree.
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 Poor pruning can permanently damage a tree for life. For instance, any wounds inflicted on a tree will be a part of that tree forever. The tree does not repair itself the same as the human body does.
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 Large cuts are more damaging to a tree than small cuts are.

Pruning A Young Tree
 Pruning a tree when it is still young is very important. As a properly trained young tree ages, it will require far less corrective pruning later on if it was pruned correctly when it was young. Pruning is also important to a new tree since it is critical to establish sturdy, well-spaced branches and a strong trunk. Pruning a new tree should involve removing only those branches which are structurally weak. However, be sure to still maintain the tree's natural form. Scaffold branches, or the main branches connected directly to the trunk, should also be established when pruning. These branches will act as the primary framework for the tree once it matures. Such branches should be both vertically and radially spaced along the trunk for optimal tree health. Vertically, a permanent branch should be spaced a distance equal to 3% of the tree's eventual height. Meanwhile, radial branches should all be found growing outward from one point in a different direction. Just be certain to watch for included bark (excess bark enclosed deep within the crotch of the branch and trunk), which can weaken a branch's attachment. Any included bark branches should be removed to avoid dangerous branch failure.

 Young trees also should only have one trunk leader. It is important to maintain only one dominant leader to avoid structural weakness or included bark. Therefore, secondary branches that outgrow the leader branch should be pruned. Yet, be careful not to prune the tip of the leader while the tree is still young. This could negatively effect the tree. In addition, do not overprune a young tree. Some lateral branches, known alternately as temporary branches, aid in the development of a sturdy, well-tapered trunk. They also protect the tree's trunk from sun or mechanical injury. However, some lateral branches can be pruned once the tree has established itself and matured. A good rule of thumb when planting a new tree is to remove only torn or broken branches, leaving all other pruning measures for the second or third year. It is unnecessary to prune a tree that is newly planted simply to compensate for root loss. In fact, a tree left unpruned shortly after planting is likely to establish faster, with a stronger root system, than a tree pruned at the time of planting.

Pruning a Mature Tree
 Pruning a mature tree should only be done to remove weak, diseased, or dead limbs, as well as to maintain a healthy, safe, or attractive condition. Tree size, species, and age need to be taken into consideration when pruning. In general, mature trees should require little routine pruning. Yet, should the tree need cutting back, it is important not to over-thin the foliage or small branches. Foliage should be left evenly distributed along large limbs or those in the lower crown portion. In all, at least one-quarter of a tree's leaf-bearing crown should be left in tact.

 It is also important to remember that heavy pruning should be avoided just after the spring growth flush. The rapid production of foliage and shoot growth during this period causes the tree to depleat a great deal of it's energy. Pruning could leave the tree stressed from a loss of foliage. Therefore, late fall is generally considered the best time for pruning (for most varieties of trees). This will also prevent most bleeding and the risk of certain tree diseases.

Making The Cut...
 All pruning cuts should be done just outside the "branch collar" (the swollen area near the origin of the attached branch). Yet, if a permanent branch needs shortening, it should only be cut as far as a lateral branch or bud. Otherwise, the tree may end up with stem decay, spout production, or misdirected growth. If the branch/limb is very large, a "three-cut method" is advised. This is done in order to reduce the weight of the branch. The first step in the three-cut method is to locate the part of the limb that is 12-18 inches from where it's attached to the tree. Next, make an undercut at this spot, followed by a second cut on the top of the limb a few inches out from the first cut. The limb can then be removed with a third and final cut, to the point of the branch collar. This technique is suggested when removing a limb in order to reduce the possibility of tearing the bark.

If You Learn Anything About Pruning, Learn This...
 NEVER TOP A TREE! Many people are unware of the devastating effects topping can have on a tree. Since many tree services around the country offer topping as a solution, homeowners are likely to believe that it is an acceptable practice. In reality, a tree company that offers or promotes topping a tree should not be used under any circumstances.

So you still want top your tree? Here's what you can expect
A stressed tree. A topped tree will quickly starve and become vulnerable to insects and disease.
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A tree that will rapidly decay. Severe wounds caused by topping are unable to close, allowing the exposed wood tissue to decay down the length of the branch.
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A sunburned tree. With no leaves to absorb the sunlight, the trunk is suddenly exposed to more light and heat than it can manage. The sunburn can then lead to cankers, bark splitting, and death to the remaining branches.
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A hazardous tree. Multiple shoots will rapidly be produced by the tree in an effort to sustain itself. Ironically, by trying to downsize the tree by means of topping, you will have caused it to ultimately grow larger than it originally was. New shoots can grow as much as 20 feet per year. These shoots will be weak and unstable.
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You can count on having an ugly, unnapealing tree. Think about it - would you rather see leaves or stubs on your tree? Any tree that is topped will never regain it's natural form.
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Be prepared to spend, spend, spend! Pruning a topped tree never ends. You'll have to keep paying large sums of money to keep the tree under control. Not to mention that long term, the tree will cost you in decreased property value. While a healthy tree can add 10-20% to the value of a property, a topped tree will be seen as a liability at resale, since it is considered a danger and impending expense.

Options Other Than Topping...
 There are techniques that don't involve topping a tree if it must be reduced in height or spread. Any city forester would be more than happy to offer up alternatives! Some alternatives include removing branches back to their point of origin, cutting back to a lateral, or simply removing the tree completely. Starting over with a new tree can sometimes be the best solution! Remember, anything is better than a topped tree!