Dutch Elm Disease
Tips for Keeping your Elm Trees Growing Strong
Dutch Elm Disease (DED) affects all types of elms and is caused by a fungus that clogs the elm tree's water conducting system. The fungus is primarily spread from one elm tree to another by elm bark beetles. These beetles are active during the growing season.
Because they are attracted to the scent of fresh wounds, an annual pruning ban is in place in Alberta from April 1 to September 30.
What's in the Horticulture section...
A Highly Specific Pruning Time Window
Since its introduction from Europe around 1930, DED has killed millions of American elm trees across North America. Elm trees are not native to this province, but these graceful trees are commonly grown as ornamental landscape and shelterbelt plants across rural Alberta. The Society To Prevent Dutch Elm Disease (STOPDED) is a non-profit organization whose mandate is to preserve and protect Alberta's elm trees from Dutch Elm Disease. Lac Ste. Anne County is a STOPDED member and participates in a province-wide program monitoring for the presence of Elm Bark Beetles.
The only time it is legal to prune elm trees in Alberta is between October 1 and March 31.
While elm trees may only be pruned during the dormant season, they may be removed any time of year. Pruned elm wood can harbour bark beetles. To prevent the spread of DED, promptly dispose of the wood by taking it to your local landfill, or burning, burying, or chipping it. Elm stumps should be de-barked or ground to a depth of 10 cm below soil level. Do not transport or store it for firewood.
For more information about Dutch Elm Disease, to learn how to identify the signs, how to prevent it, and how to care for your elm trees visit: https://www.alberta.ca/dutch-elm-disease.aspx.
Alberta has one of the world's largest densities of healthy American elms.
"There is no cure once an elm is infected with DED, and it must be removed and destroyed immediately. We must stay vigilant to keep our elms healthy. DED can be prevented."
— Janet Feddes-Calpas, Executive Director of the Society to Prevent Dutch Elm Disease (STOPDED)