1. Nightmare on ELM Street starring a beetle, a fungus, and a willing host (1920 to present) http://www.plant.uga.edu/labrat/dutchelm.htm Dying Tree

2. Nightmare on Elm Street

3. Dutch Elm Disease

4. Discussion of control strategies and approach to genetic engineering resistance to Dutch elm disease can be found at this website: http://www.esf.edu/pubprog/elm/default.htm

5. Dutch Elm Disease -Why “Dutch”? First isolated in 1920 by a Dr. Schwarz in the Netherlands. (Dutch are blameless for the disease or its spread) - Wilt disease that attacks elm (Ulmus ssp); caused by ascomycete fungi (genus Ophiostoma, formerly Ceratosystis). - Vectored by beetles (fam. Scolytidae) and root graft. Has a saprophytic and a pathogenic stage.

6. The fungus that causes Dutch elm disease (DED) accidentally rode into the United States on elm logs shipped from France to Cleveland, Ohio, in 1931 and bark beetles bearing the fungus periodically hopped off along the way with the fungus. By the 1980s, the destructive fungus—Ophiostoma ulmi— had wiped out around 77 million American elms

7. Spread of Ophiostroma ulmi and O. novo- ulmi across Europe and the US

8. Distribution of Dutch elm disease in the United States (1978). By 1980 77 million elm trees in the US were dead. The fungus originally came from the Himalayas, traveled to Europe from the Dutch East Indies in the late 1800s. In the 1930s, it spread to the US on infected wooden shipping crates and logs from France being shipped by rail to Ohio and the devastation began.

10. Adult of the native elm bark beetle.Brood gallery of native elm bark beetle. American Elm Tree Dutch elm disease fungus (Ceratocystis ulmi) growing in a petri dish in the laboratory. Showing early disease symptoms

11. Vascular streaking caused by Dutch Elm Disease

12. 1940s 1990s Nothing much change with the disease except the hardware used to cut down the dead elm trees, until recently when resistant elms have been selected but it will be generation before the elms return, if ever.

13. Some hope for re-establishment of elms; genetic resistance

15. Authorship Professor David G. Gilchist Department of Plant Pathology, University of California, Davis dggilchrist@ucdavis.edu Humored by: Richard W. Hoenisch National Plant Diagnostic Network Department of Plant Pathology, University of California, Davis rwhoenisch@ucdavis.edu