If you live on Waterbury Drive, Hollington Road, WhiddenGate, Royal York Drive or one of many other streets in Lindenwoods or some of the other newer neighbourhoods in Winnipeg, you will know all about a serious tree problem called black knot fungus.
Winter when the trees are bare is the best time to see it. I spoke to two longtime Lindenwoods residents about the problem. They both are the original owners of their houses built in 1987. The city planted the Schubert chokecherry trees at that time. They are beautiful trees with their distinctive wine-coloured leaves that grow to a height of 20 to 30 feet. They grew quickly and contributed to the beauty of the neighbourhood.
Around 2000, the black knot fungus began to appear. It produces very unsightly black masses on the branches of the tree called galls. These galls can each grow to a size of four to six inches and there are dozens of these galls on the worst-affected trees. Some of the branches eventually die off, but the disease does not usually kill the trees. Instead, it turns a beautiful ornamental tree into something quite ugly.
Both residents that I spoke to, one on Waterbury and one on Hollington, told me that the City of Winnipeg will not do anything about the problem. Although the trees are on city property, there is no budget for pruning Schubert chokecherries for black knot. Both homeowners have had to take matters into their own hands and have bought pruning tools which they use to prune off the fungus every year.
Nevertheless, when I visited them in January, their trees had a lot of black knot galls on the branches that had redeveloped just in the past year. After speaking to these two residents, I spoke city forester Martha Barwinsky. She of course is familiar with black knot and was able to confirm that as of right now there is no cure for the fungus and no way to prevent it infecting the Schubert chokecherries. She told me that the city stopped planting these trees about five years ago and would only begin planting them again if a variety were developed that was resistant to black knot.
The trees were widely planted in new developments in the 1980s and 1990s but the city does not have an accurate count of how many were planted or where. An inventory of the city’s trees is under way.
Barwinsky confirmed that the chokecherries are not being pruned any more frequently than other boulevard trees, currently once every 13 years on average. The city does remove the trees if the infection is very severe and has replaced from 150 to 200 of them each of the past three years. Barwinsky herself has seen black knot kill trees when it totally covered the crown of the tree.
We all know about Dutch Elm disease gradually killing off our elm trees. Many of us are aware of the emerald ash borer which is on its way here to go after our ash trees. Black knot is eliminating the Schubert chokecherries. What’s left?
Joe Leven is a Linden Woods-based writer.
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