Dutch Elm Disease

Almost every Elm tree in Britain has been lost. (Except perhaps those of a slightly different species in Scotland.)

The cause is a virus carried by a beetle that had its home underneath the bark of the elm. The beetle, which I understand, had been living on the elms for centuries, with no adverse effect, suddenly became a carrier of the virus, and spread it from tree to tree. Until every one was dead.

The beetles are not to blame. What is to blame is that (I think it was around the 1960s) infected timber was imported, and the beetles in those timbers spread into the surrounding elms. That this is so is confirmed by studying the pattern of encroachment of elm death - from the ports (I forget which, but think there were two of them) at which the infected timber arrived.

Problems

First level causes:

Second level causes:


Copyright (c) Andrew Basden 1999. Comments, queries welcome. to "G @ basden . u-net . com".

Last updated: 10 September 1999. 7 February 2001 email.