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Caring for our trees

Black Knot Disease

Black knot is a common fungal disease that affects members of the Prunus species of trees and shrubs in our region. It develops as thick black, tar-like swelling on twigs and branches. Fortunately, it is easy to identify and remove the disease before it disfigures and eventually kills your trees.

Elm Pruning Ban

Dutch elm disease (DED) is a deadly disease that can affect any elm tree. Alberta currently has the largest DED-free American elms in the world, but it is important to remain vigilant to prevent the disease from infecting our trees. To that end, pruning of elm trees is prohibited throughout Alberta each year from April 1 until Sept. 30.

Tree Roots on Private Property

Call, Don't Cut. Tree roots on private property may be growing from a tree on your property, on a neighbour's property or on Municipal property. Schedule a Tree Doctor visit by calling the PULSE Line at 780-743-7000. Municipal Arborists can help you determine who owns the tree and can make recommendations for steps you can take. Municipal Arborists cannot remove roots or trees on your property.

Spring Tree Checklist

  • Prune dead branches
  • Check for pests
  • Remove salty snow
  • Room to grow
  • Refresh mulch
  • Fertilize
  • Water

After the long winter your trees and shrubs are enjoying the warm air and sunshine. A good time to do some spring tree maintenance is when snow is melting.

Tips for a healthy landscape

Inspect for dead and broken branches and remove them with proper pruning cuts. While winter is the best time to prune, a little spring refresher is okay as well, especially if it means removing Black Knot before the leaves appear.
Check for pests like caterpillars, which can be removed by hand, or aphids, which can be sprayed off with a garden hose. Clip off small branches with egg sacks and throw them in the garbage.

Sidewalk salt is hard on trees. Remove melting snow around trees that is from the street, sidewalk or driveway and may contain salt or sand. A good soaking will help reduce salt impact as well.

Remove any decorations, cables or wrap from trees. Make sure your tree has room to grow and won’t get damaged by rubbing or constriction. Bark is just like skin and doesn’t like to be wet or chaffed.

Mulch breakdown is increased in spring. Leave the bottom layers of mulch in place to decompose, adding nutrients to the soil. Top up mulch to no more than 10 centimeters (4”), making sure you keep it away from the trunk. As your tree grows in size, you may want to widen your mulch area. Ideally any area that is under the tree would be mulched and kept grass and weed free.

Spring growth is fragile and can be easily damaged by herbicides, pesticides and even over-fertilization. Avoid chemicals.

Fertilize with a slow-release fertilizer and follow the recommended application rate on the container.

Water on dry days. Spring growth will be encouraged by healthy amounts of watering. Water pooling at the base of the tree is too much and two or three days of hot weather with no rain can reduce new growth. Using a watering bag will makes sure your tree gets enough moisture, without washing away soil and nutrients from over-watering.


Call 780-743-7000 to reach the Pulse line and ask for a Tree Doctor appointment. Municipal arborists can inspect your trees and make recommendations for tree health.

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