Dutch Elm Disease

Remember Elms?

How it was

Elm trees used to be as common as Oak.  Whole woods were Elm.  They were huge, a real classic symbol of the English countryside.  They were in parks, gardens, golf courses, lining hedgerows and in woodland. 

I remember them so vividly.  I remember how beautiful and big they were.  I remember where they were; exactly where huge individual elm trees used to stand and where they had stood for hundreds of years.  I remember their little round wind borne seeds, which showered the ground, like Autumn leaves and blew into heaps.   This mighty, strong established tree, with many different varieties.  Unthinkable that they could be gone within one decade, but they were.

Dutch Elm Disease 

Different species of Elm live both sides of the Atlantic Ocean; a remnant of when the land masses had been joined.  This disease is thought to have arisen from Asia.  From the Dutch East Indies, from what is now known as Indonesia.

In its natural homeland it fed on, but never devastated any local tree populations, as they had evolved along side them.  Problems only arose when it spread to Europe and America, most likely with cheap wood imports.

The disease was first reported in 1921 in the province of Nord Brabant in the Netherlands, which is why it was named 'Dutch Elm Disease'.  From there it rapidly spread, practically wiping out these beautiful trees right across the Continent.  By the mid 1920s they had pretty much vanished. From what I can gather; the disease ravages North America in the 1940s.

No one seemed to know what caused the disease, nor how to treat it, people used to assume that once the first few branches started to turn yellow; that was it.

Grieve 1931: "Investigations are at present being carried on as to the cause of a mystery disease, known as the Dutch Elm Disease', which is killing trees on many parts of the continent."

Because the UK is a group of Islands, separated by a large area of sea from the European mainland; we were not affected and by 1927 we banned had all imports of Elm wood from the continent.  Due to this unusually sensible measure; we managed to hold on to our Elms for about another 50 years, and then it struck.

 

It was in the 1970s.  I remember it vividly, it seemed to hit Britain and Ireland at about the same time, which was around 1975 till about 1977, buy the 1980s all the big Elms were gone. 

I remember hoping each one would survive and then observing as each in turn started to go yellow, first in patches, then the whole tree would rapidly turn brown, the bark would peel of like orange peel and all the other trees around it would follow suit.  

Dead sticks of great trees littered our towns and countryside too quickly for us to work out what was going on and for us to gather enough knowledge and resources, to do anything about it, then it was very suddenly; too late.

Dutch elm disease is one of the most serious tree diseases known to have ever occurred.  It is caused by two related species of fungi in the genus Ophiostoma, which are carried by various elm bark beetles, which would include the Large Elm beetle Scolytus Scolytus illustrated here.

Distinctive patterns left under the bark, by Elm bugs.

 How it is Now

Elm trees throw off long underground rhizomes, in much the same way as Blackthorns do.  They spread more by this vegetative method, than they do by seed.  It was this fact which saved some of the most effected species from total annihilation, as young trees would constantly sprout from the roots of infected trees.

Another factor in the tree's favour is that the disease will only effect trees, which are nearing their mature stage, when they are about to start producing seeds.  When they are about 20 foot/ 7 metres high.

For decades many woods had patches of Elm sucker thickets, but most have now been displaced by other native trees.

Many hedges still are comprised of Elm.  A cut hedge never becomes a mature tree, but still many Elm hedges died, I remember.  Not all though, many still remain completely in tact.

Not all species of Elm were effected, some of the smaller species, like Wytch and Slippery Elms hardly ever get it, but the big English Elms really suffered some horrific genocide.

Individual trees were resistant to it, but not many.  I can think of only 3 places where large Elms grow wild in Devon still.

The Elm bugs can only fly 15 miles, it is said; and to my amazement, they are still highly abundant in the Scilly Isles, which are situated more than 20 miles off the coast of mainland Brittan.  I know that for a fact, because I used to live on the Scilly Isles & Elms are everywhere.

I heard a recent report that during the crisis; Brighton town council would routinely remove any branches, with infected yellowing leaves and this simple measure saved their Elms, to this day and formed a blue print for a simple and effective form of treatment, for all Elms in the future.

Some new hybrid varieties now exist, which are supposed to be immune and I was very surprised to see just how many large Elms line the streets and parks of The Hague, in the Netherlands.  The very place, from where the problem arose.

My Efforts to assist the Elm

Elms are now very rare and collecting baby trees is really only possible from suckers.

Every year I only ever collect a few, as a large Elm population would now look unnatural.  Also I have no idea if they will reach maturity.  Many are suckers from fully grown surviving trees, but many are suckers from hedges and some are from where the great trees were killed off and still exist as big clumps of suckers.

Time will tell, I suppose.

The young sapling, shown here to the right and in the two pictures below; is one I planted about ten years ago.  It is doing very well and last year it even through off its own first sucker.  In fact the Elms transplant quite easily and grow just as fast as any of our other native trees.

Elms have this distinctive corky looking bark and their leaves and branches sprout in odd-opposite fashion from the main trunk or twig.  The leaves do the same.

 

Collecting Elm 

I have found a patch of woods, near Horrabridge in West Devon; where Elm suckers sprout abundantly, from parts of the forest floor.  If I just scrape away the soil, from around the base of this particular selected young tree; you can see the long rhizomes, from which many young trees sprout.  A nice chunk of rhizome, like this should take quite easily and hopefully help assure the Elm's survival, for future generations to see and I hope that our future generations will have learnt by our mistakes and to never let anything like this happen again.