Dutch Elm Disease in Calgary

Dutch Elm Disease, commonly referred to as DED, is a fatal and highly contagious disease of the elm tree. So far, prevention efforts have kept Alberta free of DED. However, everyone needs to pitch in to protect elm populations in Calgary and throughout the province.

Dutch Elm Disease is a fungal disease primarily spread by two species of bark beetles that carry the spores from tree to tree. The larvae tunnel beneath the outer bark of the tree, creating distinctive “feeding galleries.” However, the disease can also spread from the roots of an infected tree, meaning the fungus can be present even in the absence of these tunnels.

A tree will try to prevent the fungus from spreading by plugging the tissue used to transport water and nutrients, causing the tree to starve and eventually die. To monitor and keep track of the elm trees in your neighbourhood, you can talk to our team of experienced arborists at ArborCare® and keep the elm trees of Calgary DED-free.

Signs of Dutch Elm Disease

Let’s look at the signs of DED so that you can recognize it and eventually stop it from spreading from one elm tree to another:

• Leaves suddenly wilting. Since the upper branches are typically the first ones affected, this can be hard to spot.
• Dying branches and yellow, brown and curling leaves, usually appearing in June and early July.
• Leaves falling.
• Brown or red streaks that can be seen in the wood when the bark is pulled back.

It is critical to know that due to DED, a small tree can die in less than a month. If you are having doubts, you can request a consultation with a professional arborist to check for the symptoms.

What You Can Do to Control DED

Prevention is the only way to control DED. Fungicide treatments are available but need to be repeated often and usually only prolong the life of the tree for a few years.

• Take preventive measures
  Ensuring that your trees are strong and healthy is crucial. Consult with one of ArborCare’s experts for an assessment. Make sure to never trim elm trees between April 1 and September 31. Bark beetles are active during this time and are attracted to the smell of cut wood.
• Care for your trees
  Water them regularly from April to August and then only once or twice before the ground freezes for the season, helping them survive the winter unscathed.
• Keep your property clear
  Get our experts to remove dead elm trees and branches from your property. These are ideal breeding grounds for the bark beetles that carry DED.
• Respect the law
  Remember that it’s illegal to stock elm firewood in Alberta. Also, you shouldn’t transport elm firewood into or within Alberta, as it could spread DED.

Is DED Harmful to Humans?

DED poses no health risks to humans or animals. However, human activity can lead to the DED fungus spreading to other elms, for instance, by transporting elm woods infested with bark beetles to other areas.

How Does DED Spread to Other Trees?

First, adult females of elm bark beetles lay eggs under the bark of dead or dying trees. Then, larvae feed on the inner bark and sapwood of the tree, creating galleries and tunnels where the sticky spores of the DED fungus get produced. The new beetles emerging as adults from infected elms carry spores of the fungus on and in their bodies. As these beetles fly and chew through the bark of other healthy trees to feed, spores on their body get pushed off and start new DED infections in the process.

Another common way that Dutch elm disease can spread is through root grafts. In infected trees, the DED fungus can reach downwards toward the root system within the first season of infection. As root grafts are formed among neighbouring elm trees to allow the flow of water and nutrients, the DED fungus can infect these trees by moving through root grafts.

Keeping Calgary Free of Dutch Elm Disease

With over three decades of experience of providing tree care services in Calgary, our arborists are familiar with regulations around elm tree care and provide plant management and seasonal maintenance for commercial as well as residential clients. Schedule your service today for your tree care needs.