Although Dutch elm disease continues to wreak havoc, it appears Quebec City’s iconic tree won’t be disappearing from the landscape any time soon. After properly protecting its finest specimens, the city was even able to begin planting Quebec American elms again, something it hadn’t done for at least 20 years.
In the eyes of many enthusiasts, the American elm (Ulmus americana for short) is considered one of the most beautiful native trees on the North American continent. Some also describe it as the most elegant of all elm species combined.
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One of the capital’s star elms, seen from the Pierre-Dugas-De Mons terrace.
Photo: Radio-Canada / Catherine Lahaussee
This tree with a slender trunk, which can quickly reach an impressive size of 25 to 35 meters, can be recognized from afar by its parasol-shaped branches. Not only is it elegant and fast-growing, it can have a long lifespan, often more than a century, and each new decade makes it even more spectacular.
In North America, almost every large city had its Rue des Ormes or its Elm Street. By planting American elms on each side of the street, after 50 or 60 years, their branches eventually touched and the canopy became magnificent. We called them “green cathedrals.”
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A beautiful example of the canopy created by elm branches meeting in height, called the “green cathedral”.
Photo: Edmonton
But that was before Dutch elm disease (DED) turned everything upside down.
An epidemic of biblical proportions
The first MHO cases in the country were discovered in Contrecœur and Saint-Ours during World War II in the early 1940s. According to Louis Bernier, retired professor at Laval University, it is possible that the disease was introduced from Europe through the port of Sorel while trade with England was very active. At this point, it had been raging in Europe since the end of World War I and had already reached the United States.
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Dutch disease in Saint-Ours, 1944, photographed by René Pomerleau, Quebec’s first forest pathologist.
Photo: BAnQ / René Pomerleau, 1944 / P22191
It is estimated that it would have killed tens of millions of trees in North America in just a few decades. And we’re not even talking about the massacre that took place in Europe.
When it attacks a population of non-resistant elms, Dutch disease is 90% fatal. Only one in ten survives. On a human scale, there is no comparable pandemic. Even the Spanish Flu and Plague combined weren’t that deadly.
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Discovery of diseased elm trees in Berthierville in 1945
Photo: BAnQ / René Pomerleau / MCC Fund / P26340
It is caused by a microscopic fungus and spread by an insect, the elm bark beetle, which digs galleries under the bark of diseased or dead trees to reproduce before attacking the tops of healthy elms to feed itself.
An adult alone can carry hundreds of thousands of spores. The most beautiful trees are often affected first. Once the fungus begins to spread inside the tree, nothing can be done.
According to the expert, the epidemic occurred in two phases. The fungus that raged in the early 20th century was then dethroned by a second, even more devastating pathogen. This second wave, which arrived in Quebec around the 1960s, helped complete the work that had already begun.
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Image from a file about saving the elms in Montreal in 1985
Photo: BAnQ / Fonds La Presse / Jean-Yves Létourneau
A fight as long as it is exemplary
Since the outbreak of the disease, Montreal has lost almost all of its elm trees. Although there were tens of thousands, she was only able to save a few dozen. A drama that was repeated across Quebec, as the once-present American elm was almost wiped out of the landscape in just a few decades.
For the city of Quebec, however, things were very different. The MHO arrived a little later, at the turn of the 1970s, which undoubtedly gave it time to prepare. Above all, the city was more efficient. Concerned about preserving its arboreal heritage, it quickly adopted and subsequently maintained measures to avoid disaster, which explains why it is cited as an example today.
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Felling of diseased elm trees in the Jeanne D’Arc Garden in 1984 on the Plains of Abraham
Photo: Quebec City Archives / Le Soleil Fund / Raynald Lavoie / All rights reserved
Initially, the only way to combat the disease was preventive culling. Every infected tree was immediately removed to curb the spread of the bark beetle responsible for the disease. Added to this in the early 1980s was the spraying of insecticides and then the use of a fungicide, Arbotect, which could protect trees from the fungus.
For a time, Quebec struggled alongside several of its neighbors, Sillery, Sainte-Foy, Cap-Rouge, Vanier and Ancienne-Lorette, thanks to a program created with federal aid. But this good understanding between Quebec and the surrounding towns did not last, as was often the case before municipal mergers.
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One of the oldest elms in Quebec, photographed on the Grande Allée in 1990, when the city decided to make the American elm its landmark.
Photo: Quebec City Archives / Le Soleil Fund / Jean Vallières
From 1985 onwards, only the city of Quebec financed the protection of its elm trees, supported by a handful of partners who have continued since then, such as the National Battlefields Commission (CCBN), Parks Canada, Laval University or the National Capital Commission (NCC).
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A magnificent elm tree from the Cataraqui estate on the grounds of the National Capital Commission
Photo: Radio-Canada / Catherine Lahaussee
Good news on the horizon
Now some good news for the city: after decades of fighting, losses finally appear to have stabilized. Treating elms with Arbotect, which demonstrated 99% effectiveness on treated trees, resumed in 2018 after a mandatory hiatus that had lasted since the early 1990s. The company that manufactured the fungicide had apparently stopped registering its product in Canada.
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The elm is considered the oldest in the city and is located in the Saint-Matthieu cemetery.
Photo: Radio-Canada / Catherine Lahaussee
According to environmental consultant Christian Bélanger, these results, combined with a rigorous inventory of diseased trees in order to proceed with their felling, are encouraging.
Every year we lose some, but by eliminating the sources of infestation the mortality rate still remains quite low, making it possible to maintain a population that is still significant today.
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An aerial view of the Joan of Arc Garden allows you to see young elm trees planted to replace the felled trees.
Photo: Wikipedia / Jean Gagnon
However, treatment with fungicides is associated with significant costs. To be effective it must be repeated every three years and to protect an individual it must also be applied to surrounding elm trees, as the pathogen can travel from one individual to another via the roots. The city therefore only applies it to 400 of its finest – and most prominent – elm trees out of the approximately 2,700 elms it owns, which accounts for almost 15% of the total.
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The ancient elm trees in the Jeanne D’Arc Garden date back to when the garden was created and are now approximately 80 years old.
Photo: Radio-Canada / Catherine Lahaussee
The NBC, on the other hand, has raised the bar a little higher.
The aim is to treat 30% of the 700 elms on our territory, i.e. more than 200 trees. We treat the most majestic and those that are on the lawn. Our principle is to process as many elms as possible, even if we have to start over again.
But if we want to preserve the elm population in Quebec, we also have to plant them. However, if you want to plant a small American elm today, we will only find species from nurseries that have been produced elsewhere, including the Accolade elm from Asia, which, unlike our native tree, is not affected by the disease.
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In Quebec you can discover many small hybrid American elms, especially along the Samuel-De Champlain promenade.
Photo: Radio-Canada / Catherine Lahaussee
Research has also made it possible, particularly in the United States, to develop several hybrids resistant to Dutch disease, which the city and its partners have used in recent years. Except that, according to some, none yet compare, if only in beauty, to the famous Ulmus Americana that once bloomed in Quebec.
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An American elm tree in Old Quebec, near St Andrew’s Church. The city currently estimates its inventory of elm trees (municipal and private) at over 25,600.
Photo: Radio-Canada / Catherine Lahaussee
In my opinion, they have not managed to have specimens that have such a slender and flared shape, which means that they are in some way aesthetically irreplaceable in the landscape, says environmental consultant Christian Bélanger.
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One of the city’s oldest elm trees stands in the Saint-Matthew Cemetery on Saint-Jean Street.
Photo: Radio-Canada / Catherine Lahaussee
But that could change soon. Now that the city has apparently protected its finest historic elms, it is considering, for the first time in several decades, the possibility of planting small American elms grown in Quebec on its territory.
We are currently planning production. This is a special order as nurseries no longer produce them. It has to be a resistant species. We also need to be clear that this will not be a mass planting and there will be a lot of monitoring. Details will follow. But it’s still good news, says Christian Bélanger.
We need to figure out who could produce them and how we could distribute it all. We expect a time horizon of around 5 years to replant our streets and parks, and in any case less than 10 years. All of this still needs to be validated.
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Two American elm trees stand out on the facade of the Industrial Alliance headquarters on Grande Allée. The company has been involved in tree protection since the 1980s.
Photo: Radio-Canada / Catherine Lahaussee
Disease-resistant elms
The other good news, and it is undoubtedly the one that pleases Professor Bernier the most, is that we are now seeing certain American elms showing resistance to the disease, which could allow their entire population to recover after decades of battling it To recover pathogens calmly.
For forest pathologists, 90% mortality in a population is not bad news. This leaves 10% of individuals capable of reviving the population, and that is exactly what is happening in the elms of North America.
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Professor Louis Bernier, near a small hybrid elm planted near his home in the Saint-Sacrement district.
Photo: Radio-Canada / Catherine Lahaussee
The professor is also working on an application that could make it possible to identify Quebec elms whose genes make them resistant to the disease. This meant that every interested person could contribute to the inventory. The application would allow the American elm to be securely identified before being geolocated. “We would also make sure that the elms have not benefited from the famous fungicide Arbotect,” explains Bernier.
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A majestic elm tree in a residential area near Les Plaines in the Montcalm district
Photo: Radio-Canada / Catherine Lahaussee
Genetic selection remains the most promising route to date, as there is still no way to cure an affected tree. Teams could then take branches from these trees to harvest enough to restart production. But we have to remain vigilant, the pathogen will probably continue to adapt to new resistant trees, the professor reminds us, without losing his optimism.
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A beautiful elm tree on the facade of a house on Avenue Marguerite-Bourgeoys in Saint-Sacrement
Photo: Courtesy of Jacques A. Fortin
As we wait for the American elm to grow again in Quebec, it remains to be seen what the fate of the 14,000 mature elms located on private properties across the city will be. Although the city carries out its inventory in an exemplary manner and closely monitors their health, it unfortunately does not offer any subsidies to owners who want to protect them with fungicides. The only financial assistance program currently offered relates to the disposal of the wood after the tree has been felled, depending on the diameter of the affected elm.
The fact is that among these thousands of elms there is no reason why some are naturally resistant to the disease, recalls Louis Bernier. And whenever these elms reproduce naturally, evolutionary biology will still work in their favor.
Sources:
- Quebec City Archives
- Quebec Urban Forestry Department
- National Battlefield Commission
- Library and National Archives of Quebec
- Suzanne Hardy; Our Champions – The Capital’s Remarkable Trees – National Capital Commission/Berger