If your thinking of planting an American Elm - Don't do it: and if you have an American Elm - make sure you read this.  American Elm is one of the most beautiful and stately trees in Ontario.  Ever wonder why there is almost always an "Elm Street" wherever you go? Its large size and vase like shape made it a boulevard favorite for most older cities and towns as the canopy on a mature tree extended well above the utility wires and also provided unobstructed roadway views .  That high canopy also ensured a large shade area for sidewalks. 

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Unfortunately ,    A series of introductions of a fungus named Ophiostoma around the 1920's from Europe and later from Asia has lead to most of the American Elms being wiped out.  This fungus dooms any elm it infects as it results in blocking of the xylem ( the little pipes in a tree that carry the water upward)  and the canopy literally dies of dehydration - usually within one year. So the symptoms are rapidly dying branches throughout the canopy and the branches  hang on to their dying leaves until brown.

 

To complicate matters, the fungus is spread by a series of bark beetles that carry the fungus from tree to tree as they burrow under the bark once the tree is old enough to have thicker bark.

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 There is no treatment.  If you are lucky,  you can cut out an infected branch, prevent it from spreading further, and it might save it...but no guarantees. If you have an American Elm on your property there is a good chance it will get the disease within 20 years.  

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There are hybrids of Asian and American Elm that  are more or less resistant to the disease but the Hybrids lack the shape and desirable features of the American cousin. If you have a healthy elm, enjoy it while you have it.

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FYI - The disease is not actually Dutch in origin.  The disease was identified by Dutch scientists working in the Netherlands and somehow the label was pinned on the disease.

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