Dutch elm disease

Dutch elm disease is a fungal disease of elm trees, originally native to Asia. It has been accidentally introduced into America and Europe, where it has devastated native populations of elms which had not had the opportunity to evolve resistance to the disease. The name 'Dutch' refers to the first scientific discovery and study of the disease in the Netherlands.

Related Topics:
Fungal - Elm - Netherlands

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

The causative agent is the fungus Ophiostoma ulmi, spread by a bark beetle as the vector for infection. The fungus blocks the water conducting vessels within the tree; the first symptom of infection is usually an upper branch of the tree with leaves starting to wither and yellow in summer, months before the normal autumnal leaf shedding. This progressively spreads to the rest of the tree, with further dieback of branches. Eventually, the roots die, starved of nutrients from the leaves.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~

Often, not all the roots die: the roots may put up small suckers. These may grow up for some years into small elm trees, but after a decade or so the new trunks become large enough to support the bark beetles, and with their inevitable arrival the fungus returns, and the new tree dies.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~