Winter Pruning Essentials: Managing Black Knot in Stony Plain

STONY PLAIN, AB: The Town of Stony Plain is continuing proactive efforts to protect trees throughout the community. These efforts include monitoring and managing harmful tree diseases that can spread quickly if left untreated. One of the most common forms in Alberta is Black Knot, a fungal disease significantly damaging tree health. 

Black Knot is caused by a fungus that manifests as greenish-brown growth on branches and stems, most commonly affecting cherry and other fruit tree varieties. As it matures, the growth, becomes black and hard, restricting growth and weakening the tree, eventually causing tree death. 

However, Black Knot can be managed with proper pruning. The best time to prune is when trees are dormant, and infected areas are visible. Pruning between October and March makes Black Knot easier to identify and reduces the risk of disease spread. 

Once pruned, branches and material removed from the tree must be destroyed to help prevent the spread of the disease through the community. Diseased wood must be burned in a controlled fire pit, buried, or bagged and removed from the infected site. 

“Pruning is an important part of environmental stewardship,” says Mayor William Choy. “By remaining proactive, we help protect the towns trees and ensure they continues to benefit our community.” 

The Town is responsible for pruning on public property, including open spaces and boulevard trees, using sterilized tools and equipment to prevent disease spread. Residents are encouraged to contribute to these efforts by regularly monitoring their trees on private property for symptoms of Black Knot by following recommended pruning and disposal guidelines. 

 “Crews have begun pruning this winter, continuing our systematic, thorough approach to tree care,” says Darcy Carter, Parks and Leisure Supervisor. “Pruning is vital to tree health and disease control; we encourage all residents to monitor their properties and know the signs of Black Knot.” 

Guidance on identifying Black Knot, proper pruning timelines, and disposal practices is outlined on Plants and Trees as part of the Town’s ongoing tree health management efforts.