Trees are an important part of the urban environment. Healthy trees supply valuable economic and human health benefits and can increase property value. It takes many years to grow a mature tree and maintaining tree health is important and worthwhile.

Pruning is the act of removing dead, diseased or undesirable limbs. The objective of pruning is to produce strong, healthy, safe, attractive trees. Before pruning a tree it is important to understand why, when and how to prune.

It is recommended to hire a professional arborist who is qualified and experienced in pruning. Arborists should be certified and belong to a professional organization such as the International Society of Arboriculture (ISA).

It is also recommended to avoid tree service companies that advocate “topping” to control tree height and safety. Topping, the practice of removing large branches and tops of trees, dramatically shortens the lifespan of trees and creates hazardous trees rather than eliminating them. This type of cutting results in weak regrowth that becomes more vulnerable to insects and disease such as Dutch elm disease (DED). A topped tree is also more likely to break or uproot in a storm than a healthy tree.

Since DED and its vectors are included in the Alberta Agricultural Pests Act, it is illegal to prune elms during the elm pruning ban which runs from April 1 to September 30. It is also illegal to store elm firewood at any time of the year.


For more information on pruning, certified ISA arborists and DED visit either or To report a DED suspect elm tree or for more information, call the STOPDED hotline at 1-877-837-ELMS.

To connect with STOPDED executive director Janet Feddes-Calpas:
Phone: 403-782-8613