Dutch Elm Disease

Dutch Elm Disease

The American Elm Ulmus americana is particularly susceptible to infection by Ceratocystis ulmi, the fungus that causes Dutch Elm Disease. Spores of the fungus are carried by elm bark beetles from an infected tree to healthy ones. Female beetles dig out tunnels in the softened wood of an infected tree and lay eggs under the bark. Young emerging beetles, carrying fungal spores on their bodies, feed on a new tree and the spores get into the tree's water-conducting vessels. There the fungus grows and spreads, choking the vessels and gradually killing the tree. Some species of elm are more resistant to this fungus and hybrids between American and Asian species of elm are less prone to infection. The fungus probably reached the Netherlands from Asia during the First World War and it was seen infecting American Elms in 1930. [CH] {EN}