STONY PLAIN, AB: The Town of Stony Plain is continuing proactive efforts to protect cherished trees through the Black Knot Awareness Campaign. Black Knot disease, caused by the fungus Apiosporina morbosa, manifests as greenish-brown to black swellings on tree stems, most commonly affecting cherry and fruit tree varieties.

The fungus spreads primarily through spores during warm, wet weather, using carriers such as splashing water, wind, birds, and insects. This disease has become increasingly common, and can pose a potential threat to susceptible trees.

“Protecting our trees is essential for preserving Stony Plain's natural beauty and environmental health,” says Mayor William Choy. “By raising awareness and continuing to promote best practices for tree care, we can work together as a community to mitigate the impact of Black Knot disease.”

Black Knot disease's distinctive appearance starts with a small olive-green growth at a succulent growing point or on a short twig with fruit buds. Over 2 to 3 years, this swelling matures into a hard, black growth that measures 10 to 15 cm and often becomes somewhat ruptured. During the bloom period, these growths release a significant number of spores, accelerating the spread of infection and promoting further growth both internally and externally, ultimately leading to the demise of the tree branch.

To tackle this challenge, the Town of Stony Plain continues its strategic Black Knot pruning rotation, which is divided into 5 zones. “Crews will begin work in zone 1 in Fall 2024, continuing our systematic and thorough approach to tree care,” says Parks and Leisure Supervisor, Darcy Carter. “Pruning occurs between late Fall and early Spring when the trees and spores are dormant, making the knots more visible. The Town is responsible for pruning infected trees 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 for symptoms of Black Knot and following the guidelines for pruning infected branches. For detailed information on identifying Black Knot, the ongoing pruning zones, and resources for tree pruning companies, visit Plants and Trees.