Trees are susceptible to diseases such as Dutch elm disease (DED) and black knot. These diseases can spread rapidly amongst trees throughout the City. 

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. 

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.

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 is closed for the season. 

Topics in this section

Black Knot

Black knot fungus (Apiosporina morbosa) is a common disease of the Prunus family (i.e. Schubert,...

Dutch Elm Disease

In recent decades, Dutch elm disease has made its way across Europe and was eventually introduced...

Ash Tree Health

Tree health is important to maintain St. Albert’s urban forest and the benefits that come with a...