Learn about Dutch Elm Disease

Learn about Dutch Elm Disease

Part of our role as tree owners is knowing and understanding conditions that could negatively affect their health. Dutch Elm Disease (DED), which first hit St. Paul in 1961, is an important tree disease to know about if you live in Minnesota. Communities, such as St. Paul, often have a proactive, community approach to DED. If you are concerned about the health of your elm tree, we encourage you to look into any community efforts in your area, but knowing what the disease is, how to spot it and how to manage it are important as well.

What is Dutch Elm Disease?

DED was first spotted in the Netherlands, which is how it got its name. It is caused by a fungus and is transmitted by the elm bark beetle. These beetles grow and reproduce in elms, eating live and dead tissue of elms. Trees that are infected in the spring experience faster deterioration than those that get the disease later in the year. Although there are ways to spot DED on your own, lab testing is the best way to identify the presence of the disease.

How do I spot it?

Before there are signs of the disease in plain sight, you can spot the first signs by looking a little deeper. Infected trees show brown discoloration on the wood beneath the bark. This will be present before the leaves are affected. Leaves will show signs of the disease when they begin to yellow and wilt, eventually turning brown and curling. An infected tree will deteriorate quickly, sometimes dying within a year of the infestation if they are particularly susceptible to DED (which is the case for the American elm).

How do I manage it?

Although DED is devastating, there are ways to manage it. At the first stages of the disease, you can prune the branches that are dying or dead to try to contain the disease. Inspect your elm trees regularly to monitor any progress the disease might have made. Once the infected wood is removed from the tree, it needs to be destroyed so that it cannot house new elm bark beetles. Many owners of infected elms have tried insecticides, but they are often ineffective. However, if a tree has not yet shown signs of DED, or if the tree is newly infected, you may want to consider preventing it or slowing the growth by injecting fungicides. This method can also be expensive but may be worthwhile if your elm is valuable to you or your property. You may also want to look into disease resistant elms, which are specially bred.

Want to know more about tree diseases and infestations in Minnesota? Check out our post on Emerald Ash Borer

tree diseas, dutch elm disease, DED