Trees

Spring tree checklist

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.

• Prune dead branches
• Check for pests
• Remove salty snow
• Refresh mulch
• Remove ornaments and lights
• Fertilize
• Water

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 is a highly contagious fungus that affects cherry and plum trees. Extreme levels of black knot can lead to tree death, as well as being unsightly and stressful to the tree. The fungus is inactive in winter and won’t spread as readily as it will if pruned in summer.

During winter or early spring, simply prune knots out of trees and place them in the black garbage bin or take them to the landfill for free as organic waste. RMWB crews will be out removing black knot from boulevard and park trees as well. If you see black knot on a RMWB tree, please contact PULSE and give a description of the location. You can also request a Tree Doctor appointment for advice on how to remove black knot from your tree.

Clearwing ash borer

The Clearwing Ash Borer is a native species of clearwing moth whose larvae can quickly damage and even kill ash trees. To spot a clearwing ash borer infestation, look for the following signs: 

• Holes and damage on the trunk and branches made by woodpeckers as they search for ash borer larvae.
• Pupal cases on the trunk, left behind as the ash borer emerges from the tree.
• Sawdust-like frass borings at the trunk’s base, on branches or in any holes in the bark.

Municipal crews will remove dead or dying ash trees from public boulevards and parks. In these cases, replacement trees may be planted if the area is suitable for re-planting. 

If you see signs of a clearwing ash borer infestation on a RMWB tree, please contact PULSE and give a description of the location. If your ash tree shows signs of an ash borer infestation, you can also request a Tree Doctor appointment for advice on treatment options.

Elm pruning ban

Dutch Elm Disease (DED) is a fungal disease spread by bark beetles that can affect elm trees. 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 reduce the risk of DED, pruning of elm trees is prohibited throughout Alberta each year from April 1 until Sept. 30.

Symptoms of DED begin with the yellowing of leaves in the upper branches mid-summer, with the damage spreading over the next couple of years and eventually killing the elm tree. The best way to prevent DED is to keep your trees healthy by following the tips below.  

Tree roots on private property

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 . 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.

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.

Questions?

Contact Pulse and ask for a Tree Doctor appointment. Municipal arborists can inspect your trees and make recommendations for tree health.