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Severe Crown Reduction? It’s Just Topping

Severe Crown Reduction? It’s just Topping by another name

By Maureen Sexsmith-West, ISA Certified Arborist PR4600A

If topping is so bad for trees – why does it happen so often? This method of pruning is frequently done by uneducated and untrained people in the tree care industry. Consumers fail to understand the adverse effects or sadly, they are stuck with the end product. (For tips on selecting a tree care company click this link: )

Topping does not keep large trees small or make them safer. On the contrary, it only temporarily reduces size and ultimately makes the tree more dangerous. It also increases the cost of maintenance over the life of the tree. This is the case with both deciduous and coniferous trees.

Professional agencies such as the International Society of Arboriculture, Tree Care Industry Association and the American National Standards Institute all view TOPPING as an UNACCEPTABLE PRACTICE. Cas Turnbull of Plant Amnesty refers to this out of date practice as “an act of vandalism” and is “the largest single threat to our urban forests”.

Guidelines by the Province of Alberta to prevent Dutch Elm Disease, state: “Improper pruning techniques and tree topping can weaken the elm tree and increase the risk of attracting EBB’s. Tree topping is not an approved pruning method. All pruners should be trained and certified.” In fact, many municipalities (Brooks, for example) now have by-laws that require a permit to prune or remove municipal trees.



Excessive removal of branches and leaves that feed the trunk and root mass cause dieback. Photosynthesis is the food production factory for trees. By removing the leaves you, in essence, starve the tree. While your tree appears to bounce back (or ‘fluff up’) with numerous branches full of large leaves – this is a panic response. A typical leaf of a poplar is 7 to 12 cm long. In this photo, it is twice that. It often results in extensive suckering along the root system (often in the middle of your lawn or in your neighbour’s yard). Now you have hundreds of baby trees to navigate while mowing. Treating them with herbicides can further contribute to tree mortality.


Internodal pruning or severe crown reductions (as described in a recent Lethbridge Herald Article) are all terms that are used to describe TOPPING. The unprotected stubs are unable to ‘wall off’, create wound wood and protect themselves against invaders. It also releases a flood of pheromones. These scents attract insects. Unprotected stubs are easy entry points for micro-organisms that breakdown wood. Decay and dieback are imminent. Trees seldom survive excessive pruning – the older they are, the less live wood removal they can tolerate. It is essentially a staggered, expensive removal system.


Branches that develop have very little holding capacity making them hazardous. They have a high rate of failure in winds or under snow loads. In some species, shoots can grow 10+ feet in one season. Before you know it, it is back to the same height it was originally. The real difference is that you have created a liability that can cause extensive property damage or injure people. In the case of evergreens, they need the single strong leader to distribute snow and rain along their pyramidal form. Removal of the leader results in competition from remaining branches causing co-dominant leaders and decay of the stem. They are very susceptible to breakage from snow and wind.

Want proof? Seeing is believing. Sadly, this 100+ year old tree is situated at the front entrance of a organization with very high traffic volumes.

Response growth is taller than the height of the original pruning cut.

Note the decaying stubs, blistering bark, oozing and numerous sprouts.

Here you can see the bore holes from insects and the entry hole of a nesting cavity near the base of a 12 inch limb.


Topping destroys the natural beauty and form of a tree. In winter it resembles a porcupine or something that belongs at a haunted house. In summer is looks like a giant lollipop of dense twigs and leaves. A well maintained landscape can contribute significantly to the value of your property. On the contrary, it can be viewed as a detriment and a liability.


By exposing the trunk to full sun, the tree becomes susceptible to sunscald. This results in cankers, cracking and dead tissue. Certain varieties of trees are best pruned at a certain time of year – know what you have and when is the best season to prune it. The increased sun will expose turf and under-story plants to higher heat and drought stress – increasing your need to irrigate more to maintain them. Shade loving plants will have to be relocated. You may also see a change in your utility costs.

Consider these alternatives:

  1. Trees are never too big – they simply grow in the form of their species. Embrace the fact that you have a mature tree and take pride in your carbon capturing, oxygen producing factory.

  2. Have it Properly Pruned – A certified arborist can offer a variety of pruning techniques and solutions that won’t harm your tree.

  3. Remove and Replace – some trees should be removed because they are the wrong species for the location or they are in poor condition. It may be better to start over with a better tree selection for the location.

As a Certified Arborist, my training and experience in arboriculture and tree risk assessment enable me to provide you with a qualified diagnosis. I would be pleased to assess your tree in relation to your concerns. We can review any alternatives that address health and safety issues and develop a plan of action that is cost effective, does not adversely affect the future health of your tree or diminish your property value.

I value trees for the numerous benefits they offer you, wildlife and to future generations. Let me be the voice for your tree.

For more reading by tree industry associations:

The illustration above can be found on “The Ugly Truth About Topping” produced by Liz Ball, Marple Tree Commission


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