Dutch Elm Disease

Dutch elm disease poses a significant threat to Edmonton's inventory of disease-free elm trees.

Reminder

From April 1 to September 30, it is illegal to prune elm trees as per the Community Standards Bylaw 14600 . This ban on pruning helps to prevent the spread of Dutch elm disease.

Be on the lookout for elm leaves that turn yellow during the summer.

What Is Dutch Elm Disease

Dutch elm disease (DED) is a deadly disease caused by a fungus (Ophiostoma ulmi) that can affect any elm tree. Since its introduction from Europe about 1930, it has destroyed millions of American elm trees across North America.

Edmonton has one of the largest concentrations of uninfected American elms in the world. An isolated case of DED was discovered in Wainwright, Alberta in 1998 and two trees in Lethbridge, Alberta tested positive in 2020.

The Problem

Although Alberta is still disease-free, the beetles, which carry the disease, have been found in Edmonton and St. Albert (since 1995), Calgary (since 1994), and Vauxhall (since 1996). Since then, they’ve been found across the province, from Medicine Hat to Grande Prairie.

In other areas, DED arrived three to seven years after the first detection of elm bark beetles. Therefore, the City of Edmonton is investing in a preventative strategy to protect one of the world's last stands of healthy elms.

Keeping Track of Elm Trees

Watch for these symptoms of Dutch elm disease:

Drooping and yellowing leaves in summer
Branches with smaller leaves than the rest of the tree
Branches with no leaves
Brown wilted leaves that remain on the tree

Monitor the condition of the elm trees in your neighbourhood. If you suspect Dutch elm disease on any public or private elm tree, please call 311 or report them online.

Apart from being the ideal breeding material for the beetles, elm firewood is especially problematic as it is easily and often transported from place to place. It is in this way that the beetles and DED are most readily transported long distances, and it is likely that the introduction of the beetles into our city occurred in this manner.

Because Dutch elm disease can be carried on elm firewood, provincial regulations prohibit storage, transport and sale of elm firewood. So if you go camping, please do not transport firewood.

Pruning and Disposing of Elm Wood

Prevention of Dutch elm disease starts by keeping elm trees healthy. Prune all dead wood that provides beetle habitat. Pruning of healthy elms, however, should only be done during the winter season when the beetles which are attracted to fresh tree wounds are not active (October 1 to March 31).

According to Edmonton's Community Standards Bylaw 14600 it is illegal to prune elms between April 1 to September 30.

Elms that suffer major injury such as a lightning strike or storm damage during the summer may be pruned, but branches must be chipped, burned or buried promptly. A City inspector may also approve limited clearance pruning to mitigate electrical hazards or to avoid construction damage. Written permission must be obtained prior to any elm pruning performed during the elm pruning ban (April 1 to Sept 30) by contacting the City at 311 or reporting online.

Elm branches and logs must be disposed of properly. Bundle small branches, 25 mm (1 inch) or less in diameter, and place at the curbside for Yard Waste Collection or in your Food Scraps Cart.

Take large branches and logs up to 1. 2 m (4 feet) to special elm disposal bins at one of the following free elm wood recycling sites at one of the City's Eco Stations.

Large loads of elm wood, more than a half-ton truck, and commercial loads must be taken to the Edmonton Waste Management Centre.

For citizens who need help with pruning, the City recommends using professional arborists certified by the International Society of Arboriculture (ISA).

Elm trees may be removed any time of year, however all wood must be properly disposed of (cannot be kept as firewood) and elm stumps should be de-barked or ground to a depth of 10 cm (4 inches) below soil level.

Remember, Edmonton bylaw prohibits the storage of any elm wood that you may have pruned. Please help us keep Edmonton's elm trees DED-free.

Symptoms

Dutch Elm Disease Symptoms The early symptoms of the disease appear from the latter half of June to the middle of July when the leaves on one or more branches may wilt, droop and curl. The leaves then turn brown and usually remain on the tree.

If the tree is infected later in the summer, the leaves will droop, turn yellow (this is called flagging) and drop prematurely. Late season infections are easily confused with normal seasonal changes.

All of these symptoms are accompanied by brown staining in the sapwood that can be seen by removing the bark of infected twigs.

Since other diseases like Dothiorella Elm Wilt can cause symptoms similar to those of DED, positive identification requires a laboratory test.

Signs of Beetle Activity

Beetle emergence holes, the size of the diameter of a pencil lead, and/or sawdust on the bark, indicate burrowing beetles. The beetles are 3.5 mm (1/8 inch) long. The characteristic pattern of the breeding galleries on the surface of the wood under the bark can also be used to identify the two elm bark beetle species.

Please report any suspected Dutch elm disease problems on private or public elm trees to 311.

Biology

The smaller European elm bark beetle has been found in Edmonton since 1995.

European elm bark beetles Dutch elm disease is noted for its severity because it destroys American elm and severely damages other elm varieties. The disease is caused by a fungus (Ophiostoma ulmi) that is spread mainly from one tree to another by two insect species, the native elm bark beetle (Hylurgopinus rufipes) and the smaller European elm bark beetle (Scolytus multistriatus).

These two species breed in dead elm wood such as broken branches in an elm tree canopy or cut logs from pruning or salvage operations. The new brood of bark beetle adults produced in a diseased elm acquires sticky fungal spores on their body surfaces.

These beetles then fly to feed on healthy elm trees. In burrowing to feed under the bark, the fungal spores are easily rubbed off the beetle's body.

Spore germination then leads to the fungus spreading and plugging the tree's water conducting elements, causing infected branches to wilt and die. Eventually the tree dies completely, usually within one or two seasons.

Presently, Dutch elm disease ranges throughout most of the United States and Canada where native and ornamental elms are found. It was first identified in Ohio in 1930.

By 1944 it had reached Quebec and spread to Ontario by 1946. In 1975 it had reached Manitoba and by 1981 it appeared in Saskatchewan. Alberta still represents one of the last outposts of uninfected elms in North America.

Telephone	311
TTY	780-944-5555

Telephone

311

TTY

780-944-5555

Reminder

Be on the lookout for elm leaves that turn yellow during the summer.

What Is Dutch Elm Disease

The Problem

What You Can Do

Keeping Track of Elm Trees

Pruning and Disposing of Elm Wood

Symptoms, Signs and Biology

Symptoms

Signs of Beetle Activity

Biology

The smaller European elm bark beetle has been found in Edmonton since 1995.

Online Reporting to 311

Pests/Sick Trees

Dead Trees

Overgrown Trees

Tree/Branch Damage

For More Information

Pest Management

Dutch Elm Disease

Reminder

Be on the lookout for elm leaves that turn yellow during the summer.

What Is Dutch Elm Disease

The Problem

Keeping Track of Elm Trees

Pruning and Disposing of Elm Wood

Symptoms

Signs of Beetle Activity

Biology

The smaller European elm bark beetle has been found in Edmonton since 1995.

Pests/Sick Trees

Dead Trees

Overgrown Trees

Tree/Branch Damage

Related Links

Elm Tree Identification

Society To Prevent Dutch Elm Disease (STOPDED)

For More Information

Pest Management