The Great Elms

By Al Lowe
Contributor

Once upon a time, when the early settlers moved into the interior of North America, they found immense forests of gigantic trees. Along most of the watercourses, they came upon a species, which became one of the most planted trees of eastern North America, the American or White Elm, Ulmus americana.
Planted alone or growing in a pasture field, its shape is unmistakable. The solid, heavy trunk rises perhaps 60 or 70 feet before branching, and the top spreads out in a vase or umbrella shape. This long, unbranched trunk, and the spreading habit make it ideal for city planting. Almost every town in eastern Canada has its share of elm-lined avenues. In the wild, it grows chiefly in wet areas, and it doesn't mind standing in water for a long time in the spring.
Old elms are sometimes very large, up to 125 feet high and 10 feet or so in diameter. The spread of the canopy may go over 160 feet in diameter. Elms are not really long-lived compared to some trees, and they usually start to die at about 150 years. But I know of at least one, in the town which I used to live, which was over 250 when it succumbed to the Dutch elm disease.
This disease is one of the biological disasters which we have somehow imported from Europe. It is called Dutch because it was first studied in Holland just at the end of the First World War. The disease itself is a fungus. The fungus grown mainly in the vessels and tubes which carry water and other things around inside the tree. The fungus is spread by an insect, the Elm Bark beetle. The larvae feed and develop between the bark and the wood, making a system of tunnels. When the adult beetles emerge and fly to other trees, they carry the spores of the fungus along with them.
If you have visited southern Ontario in the last couple of decades or so, you will have seen hundreds of thousands of dead elms, everywhere you look in the open countryside. A few years ago, the disease arrived in this part of Ontario and in Manitoba. We have already lost many of our most majestic trees and will undoubtedly lost many more.
Infected trees usually have leaves turning yellow or brown as early as June. They then fall off if the tree has a severe infection. Once the disease has reached this stage, it is generally doomed. There are some measures which can be taken in the early stages, however, they are quite costly, and it requires a lot of time and work. Trees which cannot be saved are cut down and burned, which helps to reduce the spread of the disease. Let is hope that some of our big shady elms can escape this plague.