Micropropagation of Mature Trees of Ulmus Glabra, Ulmus Minor and Ulmus Laevis

About 40 species of elms (Ulmus spp.) occur throughout the temperate regions of the Northern Hemisphere. Elm trees are highly valued for their cold tolerance, their landscape value as well as for their timber. Unfortunately, in recent decades the fungal vascular wilt disease caused by the vascular wilt fungus Ophiostoma ulmi and more recently by highly aggressive O. novo-ulmi (Et-Touil et al., 1999), has devastated the elm populations of Europe, North America and central Asia. This has lead, in both Europe and North America, to the beginning of breeding programmes in an attempt to produce resistant individuals. However, production of disease resistant elm trees via conventional breeding has met with limited success owing to the long time scales involved in breeding programmes and difficulties in obtaining locally climatically adapted trees. Some resistant material has recently been released in North America and the Netherlands for trial plantings (Gartland et al., 2001).