Dutch Elm Disease
Dutch Elm Disease is a serious disease amongst the elm trees and is a fungal disease that is spread from elm to elm by the elm bark beetle. It took hold of elm trees in the UK in the 1960's and destroyed a large number of elm trees.
All Elm trees are susceptible to the disease, though the English elm seems to be particularly susceptible.
Symptoms of dutch elm disease can be seen in an elm tree by sudden yellowing of the leaves followed them going brown and shriveling up. If the bark is stripped from the branches of the tree it will be possible to see brown streaks on the wood. The affected tree will die as far as ground level. It is possible for regrowth to occur from suckers if the tree is not completely killed.
As mentioned above, the disease is spread by the native elm beetle. Once the elm of a large enough size (usually 13 to 14ft) the adult elm beetle will become attracted to it. The beetle lands on the tree and feeds on the healthy living bark. When they do this, they spread fungal spores to the outer growth ring of the tree, underneath the bark. This fungus then grows and spots the water conduction of the tree taking place. The branche then dies and will not re-grow. The adult beetles also lay their larvae in underneath the bark of these dying branches. The larvae then forms galleries which spread through the tree. By the time the larvae hatches into fully grown adult beetles the whole tree is riddled with spores.
It is now possible to by a hybrid version of the elm tree and these elms are promising to have a good resistance to the disease. The parent elms, however, are now native elms and so the hybrids will have a different growth rate to the usual elm tree species.
