Excerpt from the report: Dutch elm disease was discovered in Cleveland, Ohio, in 1930 and around the port of New York in 1933. The causal fungus, Ceratocystis ulmi (Buisman) C. Moreau, was introduced on elm-veneer logs imported from Europe. Soon the disease appeared along railroad rights-of-way and at ports of entry. Since then, it has spread and is reported in 42 States. The disease has caused extremely heavy losses of elms, Ulmus, both wild and those planted as shade trees. It is the most destructive shade-tree disease in North America. The fungus attacks all species of elms, but some are more susceptible than others. Trees in the related genera Zelkova and Planera have become diseased when artificially inoculated with the fungus.