What is Dutch Elm Disease (DED)?
It is a type of fungal disease known as a vascular wilt because the fungus blocks the vascular (water transport) system. This causes the branches to rapidly wilt and die. The reason the disease is called ‘Dutch’ is that important early research was carried out in the Netherlands.
Symptoms of Dutch Elm Disease
Tree damage is usually seen in summer and early autumn. To identify if your elm is infected, you will need to know the signs of the disease. If you’d prefer to have an expert inspect your trees, contact the certified arborists at Omni Tree Service.
What does Dutch Elm Disease look like?
- Peeling back the tree bark will show brown or purplish streaks of discoloration in the outer layer of the wood
- Yellowing/browning leaves or other discoloration
- Wilting (flagging) leaves that often turn brown, shrivel up, and may eventually fall off
- Dead leaves that have not fallen off the tree
- Wilting leaves and young shoots present at the same time
Initially, only a part of the tree crown may be affected but symptoms may progress rapidly throughout the crown. Death may occur quickly in trees infected in early spring, while trees infected later in the summer may survive longer.
How Dutch Elm Disease Spreads
The disease is spread by elm bark beetles.
- The adult female beetle creates a tunnel in the wood of dead or dying elm trees as she feeds.
- As she goes, she lays eggs that hatch into larvae that begin to feed and create more tunnels extending from the original. The pattern of tunnels is called a gallery.
- The Dutch Elm Disease fungus produces sticky spores in these galleries called conidia.
- When larvae breed in infected elms, the newly hatched adult beetles are contaminated with the conidia.
- The contaminated adults carry thousands of sticky conidia on their bodies. When they fly to healthy elms to feed on young bark, they introduce the pathogen to the new tree.
- The new tree then becomes infected with the fungus.
Dutch Elm Disease Treatment and Prevention
Elm trees should be diligently inspected several times each growing season. Our experienced arborists will inspect your elms, decide on a treatment plan that best fits the severity of the disease, and work to prevent the disease from spreading.
The disease cycle must be interrupted in order to gain control of the situation. To do this, treatment and prevention may include:
- Prompt removal of diseased trees or branches. This will limit the elm bark beetle population and eliminate the source of the DED fungus
- Using insecticides. This will kill the contaminated beetles before they can spread the disease to more elms.
- Breaking root grafts between trees. Large trees near each other are likely to have root grafts that will need to be broken to prevent the spread of the fungus.
- Injecting fungicides. This can prevent new infections or prevent the fungi from spreading to parts of a tree that are not yet colonized.
- Burning, chipping, or burying infected wood. This is done so that it cannot provide a home for beetles.
Tree Service St. Louis
Our certified arborists are experts when it comes to inspecting trees and treating issues like Dutch Elm Disease. Contact Omni Tree Service to schedule an appointment or call us at 636-324-2101.