Sick Tree Series: Dutch elm disease (DED), the story of a sickness that almost wiped out Britain’s elm tree population

18 Jun 2018

Sick Tree Series: Dutch elm disease (DED),
Sick Tree Series: Dutch elm disease (DED),
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Today it is very unlikely that you will have a mature elm in your garden. It’s a shame, but successive waves of Dutch elm disease have devastated the British population of this once prolific tree on our isle. So, if you have any young elm saplings in your garden you’ll want to do your bit to protect them from a disease that will still find and destroy them, given half a chance.

As professional tree surgeons and arborists we know a thing or two about this disastrous disease so we thought we’d share a little of that information with you, so you can help us in the battle to save the English elm.
The story of a killer
Discovered in 1910, this tree disease merrily ravaged its way through Europe’s elm population for almost 30 years before subsiding in the 1940s after killing up to one in four trees in some countries.
Then in the 1960s a more virulent strain of the disease hit Britain, and 30 years later over 80% of the UK elm population was gone. If you live in southern Britain that figure goes up to almost 100% of all mature elm trees as the English elm is more susceptible to the disease than those further north.
The guilty party close up
Dutch elm disease is a fungus that infects trees and is spread by elm bark beetles – large black/brown members of the weevil family that grow to around half a centimetre in length. These beetles feed off the younger twiglets at the tops of healthy elm trees. As they feed they spread the Dutch elm disease fungus. The tree reacts by closing down all its water carrying vessels where the infection starts. But the fungus spreads so rapidly this immune response does nothing to stop the disease. Eventually, the entire tree dries out as the immune response peaks, and unfortunately this creates the perfect breading and egg laying ground for those same elm bark beetles.
In late spring/early summer you may begin to notice some of these symptoms:

  • Leaves starting to wilt and turn yellow in clusters in the canopy of the tree.
  • Leaves turn brown and fall.
  • Twigs turn down and curl.
  • Shoots die back from the tip.
  • Confirm disease by peeling bark back on suspected twigs to show dark brown or purple streaks or a ring of dark brown staining in cross section.
Where one tree falls two shall grow
The reason why the elm population has not been entirely eradicated by this virulent disease is because when English elms die from the disease, not all the roots are killed off and from the carcass of the old tree new saplings can grow and spread their seeds far and wide. This is why there are hardly any mature elms any more in England, but millions of elm saplings.
However, once these saplings grow beyond a certain maturity they too become attractive to the elm bark beetle and the cycle starts once again.
To find out how a professional arborist can help you to deal with Dutch elm disease in your elm trees, call us on 0208 292 8992. We’re here to help.

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