Tree of the Week - Elm - News
Tuesday 06 December 2011
All Dutch to me
1. The world population of elms has been hit by the devastating spread of Dutch elm disease. It is almost always fatal and attacks many species. It is caused by the fungi Ophiostoma ulmi and Ophiostoma novo-ulmi, spread by elm-bark beetles. Fungal spores enter wounds in the tree caused by the beetles, and invade the xylem. The tree in turn produces tyloses which blocks the flow from roots to leaves.
2. The first strain of the disease, Ophiostoma ulmi, took hold in Europe in 1910 and North America in 1928, declining in the 1940s.
3. The second, more aggressive strain, appeared in Europe in the late 1960s and in a decade had killed about 75% of elms in the UK alone.
4. Australia has so far been unaffected by Dutch Elm Disease, due in part to its geographical isolation and good management.
5. Alberta and British Columbia in western Canada are also free of the disease.
6. Brighton & Hove in East Sussex has the largest stock of elms in the UK. A vigorous policy in the 1970s cleared infected elms and a disease management programme still runs today to ensure trees remain unaffected.
7.The disease derives its name from research carried out in the Netherlands.
8. There have been several attempts of developing resistant cultivars - some involve crossing European trees with Asiatic trees due to the latter's resistance to the disease. As such steps have been relatively recent, it is too early to say how successful the procedures have been.
1. The Langton Elm in Sherwood Forest was so special it was said to have had its own special keeper.
2. The Jo Pullen tree was planted about 1700 by the Rev Josiah Pullen, vice president of Magdalen Hall, Oxford. He was said to take regular walks to the tree, which was recorded by essayist Richard Steele (1672-1729). The tree's fame grew with age in Oxford and was used as a landmark to mark the boundary of the Parliamentary Borough of Oxford. By 1892 the tree was taken down to its stump due to rotting, was set fire to by vandals in 1909, and eventually replaced with a plaque marking where it stood.
American elm - (Ulmus Americana)
1. Six species of elm in North America.
2. Heartwood is light to mid-brown.
3. Grain is straight, although it can sometimes be interlocked.
4. Medium crushing and bending strengths, high resistance to shock loads, very low stiffness and good steam bending assets. When seasoning, it dries well but care should be taken to prevent warping.
5. Used in furniture, boat and ship building, boxes and crates, and gymnasium equipment. It can also be sliced to make decorative veneers.
Dutch elm (Ulmus hollandica)
1. Straight grained with occasional cross grain.
2. Conspicuous annual rings make for interesting figure.
3. Low bending and crushing properties, low shock load resistance, but good steam bending qualities.
4. Prone to tearing when planed and binding when sawn. Accepts glues, nails, screws and stains, and a good finish can be obtained with polishing or waxing.
5. Used in cabinetmaking, chairs, turnery, flooring, decorative burrs and veneers.
1. The elm was used by Germanic tribes to explain the story of creation, with woman formed from elm, bearing the name Embla.
2. In Greek mythology Orpheus stopped to play a love song on his harp after rescuing Eurydice from the Underworld, at which spot sprung the first elm grove.
3. Ptelea is the Dryad nymph of the European elm.
4. The inner bark was used to treat burns, colds and sore throats.
5. Medieval Welsh archers used elm to make their bows.
6. Wych elm was used by the Scottish to dye wool.
Wych elm (Ulmus glabra)
1. Known also as Scots elm, wych elm can be found in north and west UK, Ireland, Europe and western Asia.
2. Heartwood is light brown with the occasional green hue.
3. Grain is generally straight.
4. Heavy and dense with good bending and crushing properties.
5. Wych elm works well with hand tools and is good for screwing, staining and sanding.
6. Used for furniture, chests, turnery, and boatbuilding, and for sea defences in the past.
English elm (Ulmus procera)
1. Dull reddish-brown heartwood.
2. Cross and irregular grain gives interesting figure.
3. Very low shock load resistance, low stiffness, bending and crushing strengths.
4. Not easy to work with hand tools.
5. Takes glues, stains, screws and nails well.
6. Can split during seasoning.
7. Used in cabinetmaking, Windsor chairs, flooring, decorative veneers and dock work.
Did you know?
Elm is virtually indestructible under water. In the past it has been used for piles, water pipes, ships' pumps and keels. When it is alternately wet and dry, however, it is prone to rot and decay, making it ideal for coffins.