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Monday , 6 July 2020
City of Cold Lake.

Cold Lake residents asked to help trees from Black Knot fungus

Image credit: City of Cold Lake. 

Black Knot is back this spring and Cold Lake residents can help keep local trees safe.

The fungus causes brown and black knot-like swelling on the branches of the trees, which if left untreated, will eventually kill the tree and potentially spread to others.

It affects the prunus tree species, such as maydays and chokecherries.

Residents are asked to keep watch for Black Knot this spring and summer, and if spotted, to cut off infected branches.

The City of Cold Lake will again be providing a burn bin at the transfer station for residents to dispose of their Black Knot tree clippings.

There is no charge and they’ll be disposed of safely by city staff in a controlled burning container.

Here are some tips on how to deal with Black Knot:

  • Prune out the infected branches between late fall and early spring when the plants are dormant and the knots are easier to see
  • Remove the infected branches to at least 15-20 cm (6-8 inches) below the knot
  • It is best to prune an infected branch further back to a suitable location, such as a healthy collar, rather than leave a stub
  • For knots on the trunk or scaffold branches (main branches growing directly from the trunk) that can’t be removed, cut away the diseased material down to good tissue and at least 1 cm (1/2 inch) beyond the edge of the knot
  • Sterilize your cutting tools between each cut using bleach to prevent further spread of the disease
  • Destroy infected prunings immediately, as they can continue to produce spores for months after being removed

You are asked not compost these clippings.

About Michael Menzies

Menzies is the editor-at-large for Connect Media. Born and raised in Vermilion, he started in May 2018 during his NAIT Radio and Television practicum and reports on local politics, sports, and community issues. He became the Bonnyville Pontiacs play-by-play voice during the 2019-20 season. He also comments on provincial and national issues. Menzies hosts Connected! Evening Monday-Thursday at 5 o’clock. He also likes to buy books and read some of them.