What’s Happening to All the Elm Trees?
The tale of a fungus, a beetle, and Dutch Elm Disease
What are all the squiggly lines on this tree? They are part of a cycle that is destroying the American Elm.
It all started around 1930, when a shipment of logs arrived from the Netherlands carrying a hitchhiker — the European Elm bark beetle. The beetles infected native American Elms with the fungus that causes Dutch Elm Disease. Since then, more than 70 million American Elm trees have succumbed to the disease.
How Dutch Elm Disease Spreads
The European Elm bark beetle is a carrier for Dutch Elm Disease. These insects carry the spores of the fungus that causes the disease on their bodies. When they feed on a tree, the spores get into the tree’s vascular system and interfere with its ability to draw water through its roots and transport it to the part of the tree where it is needed. As a result, the leaves and branches start to wilt and die off, starting with the highest parts of the tree.
Once a tree has been infected, it can spread the disease to other nearby trees through the root system.
What about those squiggly lines?
In late summer, the female European elm bark beetle burrows into the trunk, creating a channel. She lays her eggs along the length of the channel as she…
