Our current warm weather is a great time to get out and check any elm trees on your property. Did you know you can only prune elm trees between October and March? A provincial pruning ban exists between April 1 and September 30 to discourage pruning elm trees at the wrong time.
This is to help prevent the spread of Dutch elm disease. Dutch elm disease is spread by elm bark beetles attracted to the freshly pruned trees. Pruning when these beetles are not active helps reduce the risk of your tree attracting beetles and getting the disease.
Here are a few tips to help care for your elm trees:
- Elm materials should be disposed of at City landfills – stored elm firewood is an ideal breeding ground for elm bark beetles.
- All trees should be watered every two to three weeks from April to mid-August, then again in the fall before freezing. Trees need much more water than lawns do.
- Ensure your trees are mulched properly. Mulch should be applied no deeper than four inches, not applied against the trunk of the tree (four inches away) and spread out as far as permitted. Mulch adds nutrients to the soil, conserves moisture and regulates soil temperatures. All good things for roots.
- And remember, prune your trees ONLY between October 1 and March 31 when the beetle that spreads the disease is not active.
Keep your trees free of DED
Since Dutch elm disease (DED) was first introduced to North America from Europe in 1930, it has destroyed millions of elm trees. Alberta is one of the last geographic areas in North America to be free of DED and we want to keep it that way. Elm trees are also one of the few types of shade trees that grow in Calgary so it is important to protect them.
The unseasonal snowstorm last September caused significant damage to our urban forest. Preliminary estimates indicate 50 per cent of the 500,000 public trees and 1.5 million private trees have sustained damage from the snowstorm. This means there are three times as many damaged trees on private property as there are on City land. Recovering from this storm will require us to look after our trees together.