Breeding Elms for Resistance to Dutch Elm Disease

Abstract

The use of elms (genus Ulmus) by mankind parallels the settlement and urbanization of Europe and North America (58, 97, 147), and Asia (3, 20, 22, 37, 92, 96, 108, 154). Richens (97) describes in detail the history and significance of elms in Europe and the origins of the numerous ancient elm cultivars, including the Roman introduction of the English elm into Great Britain from northern Portugal, and its later transport to Australia and New Zealand . In neolithic times the elm was used for many purposes; including food and fodder, medicinal preparations, timber for house and bam construc­ tion, bows, wheel hubs , water pipes, and other products . In modem times their graceful habit, valuable wood, adaptability, and tolerance of air pollutants have made them an important component of landscapes throughout the world. Beginning shortly after World War I, a new vascular wilt disease incited by Ophiostoma ulmi (Buism .) Nannf . (sensu lata) syn Ceratocystis ulmi (Buis . ) Moreau (Dutch elm disease) (DED) spread through the elm populations of Eurasia and North America leading to enormous economic and esthetic losses (12, 13, 40, 59). The massive loss of elms on several continents fostered numerous research programs ranging from basic investigations on host-patho­ gen-vector interactions to the use of systemic fungicides in chemotherapy (49, 63, 1 14, 1 52, 1 60). Genetic resistance to this pathogen was recognized from early research in both selected individuals and species (2, 49, 55-57, 72-75,