Published on January 31, 2023

Prune to Protect During Winter Months

Trees are an integral part of St. Albert’s botanical identity and residents take pride in the city’s lush green canopy. In fact, St. Albert has been recognized with the Tree City of the World Award from the Arbor Day Foundation for the past three consecutive years. Unfortunately, there are many naturally occurring threats to trees including common diseases, pests and invasive plant species. 

Common Tree Diseases

Dutch elm disease is caused by a fungus that clogs the elm tree's water conducting system, causing the tree to die. The fungus is primarily spread from one elm tree to another by elm bark beetles. The most common early sign of Dutch elm disease is severe leaf wilt. There are currently no reported cases of Dutch elm disease in the region and all measures are preventative.

In line with several Albertan municipalities, St. Albert has established Bylaw #5-98 which makes it illegal to prune elms between April 1 and September 30 without expressed written permission from the City. Cut elm wood should not be stored for firewood or other purposes and can be disposed of at the Mike Mitchell Recycling Depot while the Compost Depot undergoes its seasonal closure.

"By keeping elm wood out of the compost stream, it helps avoid attracting beetles carrying the disease or providing a site the beetle could use as a nursery to increase its population,” says Operations Supervisor Erin Pickard.

Black knot is a native plant disease caused by a fungus and can spread rapidly with the potential to seriously deform trees, primarily affecting chokecherry and Mayday trees. Black knot is well established throughout the province and is not regulated through any legislation.

Affected branches should be pruned during winter months when fungus is dormant to minimize spread. The infected areas should be pruned out, and cuts made 15 to 20 centimetres back from the infection. To ensure pruning equipment is properly sterilized after removal, all equipment should be washed down with a mixture of water and bleach (10 per cent).

Trees on City Property

The City’s certified Arborists ensure best tree care practices are used for regular and preventative maintenance for our approximately 65,000 planted trees on public property. The City prunes City-owned trees year-round on a five-year tree maintenance cycle. When the City removes dead or diseased trees to slow or stop the spread of disease, trees that present a risk to people and property are prioritized first. Trees that are taken out are placed on a list for replacement in the future subject to current engineering standards and utility locates.

When asked what residents can do if they would like to report damaged, broken, or diseased trees on City property Erin remarks, “Please report the issue online or call 780-459-1557. These requests are recorded and sent to the appropriate section. They will then be inspected and scheduled for maintenance based on their level of severity.”

Prune to Protect 

To help keep St. Albert a Tree City, please bring any diseased branches and elm wood to the Mike Mitchell Recycling Depot during the winter months while the Compost Depot undergoes its seasonal closure. Residents can also dispose of small diseased branches infected with black knot in a sealed bag in their Brown Garbage Cart to prevent the spread of spores.

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Last edited: February 1, 2023