Dutch Elm Disease


What is Dutch Elm disease? It is caused by Bark Beetles carrying fungal spores with them as they travel from tree to tree. These spores cause immense eradication and death for several Elm trees.

This aggressively spreading fungus that attacks the Elm population was first studied in Holland, which is where the disease gets its name. The disease has continued to spread for over 40 years and is proving to be a very difficult issue to resolve.

What should I look for?

Key components to watch for that may help you decide if you need to have an arborist come to examine your tree for Dutch Elm disease:

  • Wilting in the leaves
  • Leaves that are prematurely turning colour (yellow and brown)
  • Staining under the bark of fallen branches (the look of dark streaks- almost like floor varnish)
  • Lack of traditional winter-green smell in the leaves and bark

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Dutch Elm disease is first spotted at the top of the tree canopy. Bark Beetles prefer to feed on the new growth, which is found in the upper portion of leaves and branches. Once the upper portion of the tree is affected the symptoms move downward using the vascular system to the limbs and trunk to continue the spread of the disease.

It is very easy for healthy trees to develop this debilitating problem. The disease can be transmitted through grafted roots in the ground, The trees notice the fungus is attacking and it tries to protect itself by shutting down its vascular system. This vascular obstruction over time affects the entire tree as the fungus spreads. Ultimately the tree kills itself due to lack of water and nutrients


  1. Interpt the root system to inhibit continuing spread
  2. Prune infected branches
  3. Fungicides (not recommended by Twelve Oaks)
  4. Tree removal as a last resort

What do the Beetles Do?

Not all Bark beetles are harmful to the trees, only beetles with the fungal spores attached to them are. Bark beatles use that tree’s bark as a place to lay their eggs, and the larvae feed on the wood below the bark. The spores found on these new beatles will be passed along to other Elm’s as they move to different locations. The beatles specifically like the trees with thick bark and that are at least 15 feet or taller. Young trees are relatively safe until they reach maturity.

How do we prevent it?

The problem has been around for so long it is next to impossible to contain. Calling an arborist at the first signs of potential infection to have them complete an assessment of your tree is critical. If disease is caught early the arborist maybe able to prune away the affected branches, and if not they can help develop a course of action.

We are a family owned and operated passionate team of professionals. As hands-on owners and operators, we will be on site from the time of the call including when your property is serviced, inspected and cleaned. Choose Twelve Oaks, with over 15 years of arboreal experience you can guarantee that your request will be completed efficiently and effectively. Don't take a risk when it comes to your home and your assets. Call today.

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