Now that the leaves have fallen, please check your chokecherry (and other cherry and plum) trees for black knot, a fungus that causes black, tar-like swellings on the branches of infected plants.
This disease is widespread in St. Albert, and now is a good time to remove and properly dispose of diseased branches.
For more info, go to the Alberta Agriculture and Forestry website.
J. Runyon, St. Albert