Dutch elm Disease has affected millions of elm trees over the last 40 years and it is thought that it is still spreading through the North of the country. It is a disease that is spread by beetles that bore their way through the bark of the elm trees. These elm bark beetles spread a fungus known as Ophiostoma novo-ulmi which causes the disease to affect the trees.
There was a period of time where it would have been difficult to get hold of elm wood and with ever decreasing number of elm trees this may continue to be the case. Southampton Timber Merchants such as Timbco will be able to advise you of the best type of wood to use for your given project and will be able to let you know of any wood types that are becoming harder to come by.
The disease affects the trees by causing large groups of leaves to turn yellow, wilt and then fall from the tree itself. Any young shoots will begin to die back from the tips and twigs start to droop and bend down in a hook type shape. When the bark of the elm tree is removed dark spots and rings can be seen which further identify the presence of Dutch elm disease.
It is hard to stop the disease from taking over the tree as the beetles feed on the healthy elm trees and release spores into the water channels of the tree that then in turn causes toxins to travel around the water network that block these channels and causes the tree to die.
How the disease swept through Britain
The current outbreak took hold in Britain in the 1970s, and it spread with startling speed. Within around ten years the disease had ravaged the country, and millions of elms were lost across Europe and North America. Despite the name, the disease did not come from the Netherlands. It was named after the Dutch scientists who identified it in the 1920s.
The signs follow a clear pattern. The leaves wilt and turn yellow, shoots begin to die back, and twigs bend over like a shepherd’s crook. Finally, dark streaks appear under the bark. Like our own blood, a tree’s sap flows through the whole plant, so once it is infected the fungus can reach every part.
Some trees were saved by felling diseased elms quickly, before the beetles could carry the fungus further. Research has produced some resistant strains, but these are mostly varieties from outside Europe, so they may not grow as well as native elms or play the same role in our ecosystem.
Other tree diseases to watch for
Dutch elm disease is one of the most damaging fungal infections a tree can suffer, and it often means calling in a tree surgeon to cut out the affected parts. In some cases the whole tree has to come down. It is not the only disease worth knowing about, though.
Root diseases are caused by fungi that attack a tree’s roots, and because the damage is underground they can go unnoticed for a long time. A tree with badly affected roots can become unstable and may fall or break. Signs include discoloured leaves and branches, weak growth, brown patches, dry rot and loosely packed soil around the base.
Needle blight affects conifers, turning the needles from green to yellow and then brown. Whatever the disease, catching it early gives the best chance of saving the tree. Regular checks for changes in colour, growth and stability make it easier to act before the problem spreads.
Other problems that can weaken a tree
Dutch elm disease shows how pests can do lasting harm, but trees face several other threats that are worth knowing about. Looking after the trees on your land matters for the wider environment and for the safety of anyone nearby, so it helps to recognise trouble early and call in a qualified tree surgeon if a tree starts to look dangerous.
A lack of nutrients is a common problem. Like any garden plant, a tree that does not get enough from the soil can grow poorly and suffer damage to its branches and leaves. Fertilising the tree and spreading mulch around its base puts nutrients back into the soil where the roots can reach them.
Pest damage of any kind can leave a tree unstable, so it needs careful management and sometimes complete removal. Weather is the other big cause. Storms and high winds batter branches and can leave them cracked or hanging, and these should be dealt with quickly to make the tree safe again.