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Canada's trees: Ottawa's elms are crashing down

It begins as a tiny stowaway on a crate from Europe or Asia, a relocated piece of firewood, or just a mild winter. Within decades, millions of hectares of Canada's woodlands have been laid waste because of it. Armies of tiny insects have stripped city boulevards of stately elms and ruined billions of dollars worth of softwood. Since the 1950s, science has fought these invading waves of caterpillars and beetles using everything from DDT to pheromones and bacteria. But victory seems no closer in the fight to save Canada's trees.

A foreign fungus is causing a nightmare on elm street. For decades, the majestic American elm has been a hallmark of Canadian boulevards, front yards and playgrounds. The hardy trees can grow up to 35 metres high and can live 300 years. Then, along comes Dutch elm disease. The fungus, carried by bark beetles, is ravaging Canada's elms. Cities like Toronto have lost 80 per cent of their elms. As we see in this clip, Ottawa is next. 
. American elm trees (Ulmus Americana) are large, graceful trees that survive well in the dry, compacted soil of urban environments. Affectionately known as "the king of the shade trees," a single urban elm provides the cooling effect of five air conditioning units. Most North American towns and cities have an "Elm Street," though few of them still have elm trees.

. Dutch elm disease is a "wilt disease" caused by the fungus Ophiostoma ulmi. It is spread by elm bark beetles. Dutch elm disease essentially chokes a tree to death by plugging up the sap lines that carry nutrients throughout the tree.
. Dutch elm disease is believed to have originated in the Himalayas, travelling to Europe from the Dutch East Indies in the late 1800s. It emerged in Holland shortly after the First World War, earning the name Dutch elm disease.

. Travelling via wooden crates made from infected elm wood, the disease spread to Great Britain in 1927, the United States in 1930 and Canada in 1945 at Sorel, Que.
. As of 2004, Dutch elm disease has destroyed half the elm trees in eastern Canada and is migrating westward through the prairies.

. New strains of Dutch elm disease appeared in England in the 1960s, wiping out 17 million of the country's 23 million elms.
. There are almost 700,000 elm trees growing in Canadian cities.
. A mature elm can add thousands of dollars to the property value of a house. Most Canadian insurance companies will cover tree and landscaping losses up to five per cent of the value of a home, with a per-item limit of $500 - but losses from tree diseases and insects are not covered.
Medium: Television
Program: CBC Television News
Broadcast Date: Aug. 1, 1979
Reporter: Arthur Lewis
Duration: 6:07

Last updated: February 3, 2012

Page consulted on May 13, 2013

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