Until to-day scientists have not been able to come to a common understanding as to the taxonomy of the elm species. The reason for this unusual fact is that the different sub-species and forms of the Ulmus family freely cross in nature so that mixed forms are rather normal. In former times the elm was said to be the tree of the Planet Mercurius.

The elm reproduces by seeds as well as vegetatively by succers. Worldwide there are vast numbers of different forms and subspecies.

The appearance of the deadly Dutch Elm Disease (Ophiostoma ulmi) at the beginning of the 20th century in Europe and North America initiated breeding with elms in the USA and in the Netherlands, but also in England, France, Germany and Italy with the aim to find clones or varieties which could resist this new disease. Other means to fight the disease like chemical treatments were not effective or much too expensive.

Soon it became clear that species and forms coming from Asia (especially China and Japan) could cope with the disease quite well. It is very likely that the disease was imported from Asia, and that the indigenous elms were able to develop strategies to fight against the disease for many generations ( 500 to 1500 years).

It was not possible to import asiatic elms into Europe or America for a number of reasons. It was necessary to create elms adapted to the climatic conditions and to the fauna present. Then the new elms should have the architecture of the elms known over here, they should be vigorous, resistant to storms and snow. It also was necessary to have a good tolerance to  compacted soils in city environments and also against salt and polluted air. In Holland and also in the USA varieties were developped by crossing indigenous elms with asiatic elms, testing the crosses obtained by infecting them with aggressive strains of the disease, and subsequently testing the best ones for all the other desired features.

Since the middle of the last century those elms created by man had been planted in parks, along streets, in the countryside, extensively in hedgerows, and also in small numbers in forests. It is interesting to note that these elm varieties did have only a modest success with foresters because their vitality, their fast growth and their excellent wood quality would merit vast plantings in the woods. But the folowing seem to restrict their interest for foresters:

1.  These varieties are clones, reproduced vegetatively and therefore without genetic variability

2.   All these varieties contain at least one parent coming from Asia and do not seem to fit to the indigenous fauna

3.   These elms are propagated by cuttings and offered at the age ot two years at prices much above the price for other forest plants created by seeds

I want to discuss these three points in detail:

1.  Genetic variability

Each tree is genetically distinct. Any offspring created vegetatively is genetically the same. Any offspring by seed normally is genetically different. Prof. Eugene B.Smalley, one of the most famous elm breeders once said to me "it is my dream that my babies by free crossing with indigenous elms help to bring new generations of elms into the forests which are able to cope with the Dutch Elm Disease.

It seems that this dream is coming true: Many elms already are growing of which one parent is one of the new elm varieties whereas the origin of the pollen is unknown. Up to now they show a very good vitality. Resistance testing will follow through the years 2008 - 2010.

2.   Native trees

This notion is becoming quite ambiguous, especially with regard to trees which have many years, sometimes centuries, to live. It certainly is very important that trees in our forests must fit into their environment. It is very important that the fauna and especially the insects are happy with the trees they are supposed to live on. All elms planted have to be accepted by more than 40 different kinds of insects which are specific to this tree species. 1995 the director of forests Kettering of Bellheim Germany found the Ulmenblattkäfer on a 'Sapporo Autumn Gold'. This is remarcable because this very delicate beetle was thought to be monophag on Ulmus carpinifolia (minor). 1993 the Hessische Forstliche Versuchsanstalt held a Symposium with the title "Is the rescue of the Elm possible". One of the results was that elm breeding is the answer and here the forest scientists asked to plant such elms.

If the elm bark beetle (Scolytus scolytus), responsible for transmitting the disease cannot find any elm it will die out. In Slovakia this insect had to be put on the "Red List"

This notion has become ambiguous because of the rapid climatic changes we expect to occur within the next 50 to 100 years. The speed of change will make it impossible for most tree species to adapt because within this short period of time only two or three generations of tree species are possible. This makes a fundamental difference to annual plants which have a good chance to adapt. A native tree to the South West of Ireland today most certainly will not feel at home in the year 2070. We therefore must think of planting non-native trees to-day if we care for healthy and vital forests when our children are grown up.

3.  Price

Three elements are responsible for the high price of the resistant elm varieties: I already mentioned the costly method of production. A second factor is the cost of breeding the varieties. From the start of the breeding work until the first variety can be put on the market about 30 years of continuous attention elapse. To compensate the breeder asks for a royalty on each plant. And thirdly there are the marketing and distribution costs. All together a price comes out of between € 2 and 3 for each plant of about 1 m height.

On the other hand if you have the vigorous growth of these elms: On the same site 1992 four resistant elms of the variety "Regal" with a circumference of 10-12 cm hat been planted and 1993 two Tilia cordata "Greenspire" with a circumference of 12-14 cm. In the year 2000 the elm grew to a circumference of 66 cm whereas the lime only showed 29,5 cm !

In addition it is possible to plant in forests some resistant elms together with native elms. The average price will then be lower.

Christoph Eisele - IX 2007