c. 4000 BC and c. 1000 BC: The “Elm Decline” occurs in northwestern Europe, a widespread disappearance of elms, possibly linked to a form of DED and early human forest clearance. Fossil elm bark beetles support this theory.
c. 1780: The name Scolytus destructor (great bark beetle) is given, based on evidence that it was destroying elms around Oxford, UK.
1819-1867: Dr. Oliver Rackham presents evidence of an elm disease outbreak in north-west Europe.
1836, 1885-1886, 1896: Elm die-back and death observed in Brussels and Ghent, Belgium, attributed to the elm bark beetle in later outbreaks.
1900s – First Pandemic of DED (Ophiostoma ulmi):
1910: Dutch Elm Disease (DED) is first noticed in continental Europe.
1914-1919: Dutch scientists conduct influential research on the cause of the disease.
1921: Bea Schwarz isolates the fungus causing DED in the Netherlands, leading to the disease’s name. Barendina Gerarda Spierenburg publishes records of trees displaying symptoms from 1900-1905 onwards in the Netherlands, contributing to extensive research.
1920s-1930s: Christine Buisman identifies the sexual stage of the DED fungus and develops methods for experimental infections of elm seedlings, aiding in the selection of resistant trees.
1920s: DED appears in Europe, caused by Ophiostoma ulmi.
1922: ‘Princeton’ elm cultivar is selected by Princeton Nurseries for its landscape merit (later found to be highly resistant to DED in the US).
1927: T.R. Peace identifies DED in Britain (Hertfordshire). This first strain is mild, causing limited mortality, and largely dies out by 1940.
1928: DED reaches North America via imported timber (logs from the Netherlands destined for Ohio furniture industry). The Dutch research program to select resistant cultivars begins.
1930: Estimated 77 million elms in North America.
Mid-1930s: Chemical treatments (systemic fungicides) begin to be tried to control DED.
1937: United States begins research to select resistant cultivars.
1940s: The first DED epidemic, caused by O. ulmi, largely dies down in Europe.
1941: War demands curtail quarantine and sanitation procedures, leading to wider spread of DED beyond New York City in the US.
1944: DED first observed in Canada at Saint-Ours, Quebec, likely introduced via infected elm wood crates from Europe. DED reaches Eastern Canada during World War II.
1945-1949: Efforts made in Quebec to detect and destroy all infected trees, but the program is abandoned in 1950 due to widespread establishment.
1946: DED first found in Saint-Isidore, Ontario, likely spread from Quebec.
1947: Concern raised about bird species dying from ingesting poisoned invertebrates due to DDT spraying for DED.
1950: DED reaches the Niagara Peninsula in Ontario (from New York State) and the Windsor region (from Ohio or Michigan). DED reaches the Detroit area.
1950-1959: DED monitored in Quebec, progressing at an average rate of 3100 km²/year, killing approximately 650,000 elms.
1952: DED covers 165,760 km² in 46 counties of Ontario.
1950s: DED first appears on American elm trees on the National Mall in Washington, D.C.
1957: DED first observed in New Brunswick at Woodstock.
1960: DED reaches the Chicago area.
1960s – Present – Second Pandemic of DED (Ophiostoma novo-ulmi) and Control Efforts:
1961: DED appears in Fredericton, New Brunswick.
1962: Spraying against elm bark beetles declines rapidly after Rachel Carson’s Silent Spring (2002 publication date in source is an error for the book’s original publication, which was 1962).
c. 1967: A new, far more virulent strain of DED, Ophiostoma novo-ulmi, arrives in Britain, apparently from Canada on U. thomasii logs. It begins devastating elms in Europe and North America. DED spreads to Ontario, Canada.
1969: DED first found in Liverpool, Nova Scotia.
1970: DED reaches Minneapolis.
Early 1970s: Montreal had 50,000 elms.
1970s: Lignasan BLP (carbendazim phosphate) is introduced as the first fungicide for DED control, injected into trees. DED peaks on the National Mall in Washington, D.C.
1970-1980: 90% of Montreal’s elm trees (45,000) are lost to DED.
1973: Another consignment of U. thomasii logs from Canada found to have the new DED strain at Southampton Docks, UK, confirming its origin.
1975: DED first identified in Manitoba (Winnipeg).
1976: Toronto’s original 35,000 elms reduced by 80%. Edinburgh had some 35,000 elms.
1979: DED first confirmed in Prince Edward Island.
1981: DED covers almost 100% of the natural range of U. americana in Canada. DED reaches Saskatchewan (Regina). Quebec City initiates a prevention program.
1987: ‘Columella’ cultivar released (Dutch program).
1988: Dutch Elm Disease (Local Authorities) (Amendment) Order empowers local authorities in the UK to order destruction of infected trees.
1989: DED found in Auckland Region, New Zealand. Over 75% of North American elms lost since 1930.
1990: Very few mature elms left in Britain or much of continental Europe.
1992: The “Coalition to Save the Elms” created in Winnipeg. Dutch Trig® registered in the Netherlands. The Dutch research program ends after 64 years.
1993: Mariam B. Sticklen and James L. Sherald report on genetic engineering for DED resistance in American elms. ‘Repura’ and ‘Revera’ (hybrid cultivars) patented.
1994: Forestry Commission in UK publishes Research Information Note (no 252) on DED.
1995: ‘Valley Forge’ cultivar released (highest resistance in USDA tests). Extensive testing of Dutch Trig® begins in the USA.
1998: Only one diseased elm tree found in Wainwright, Alberta, which is immediately destroyed.
1999: A pathogenicity gene identified in O. novo-ulmi.
2000: An Italian team genetically modifies O. quercus to produce cerato-ulmin and induce DED symptoms.
2002: ‘Nanguen’ (Lutèce) cultivar released to commerce by INRA (France).
2003: ‘San Zanobi’ and ‘Plinio’ cultivars released in Italy. Scolytus schevyrewi found in Colorado and Utah.
2004: ‘Lewis and Clark’ (Prairie Expedition TM) cultivar released.
2005: Amsterdam declared the “Elm City of Europe” with 75,000 elms. Full registration of Dutch Trig® achieved in the USA. National Elm Trial (USA) begins a 10-year evaluation of 19 cultivars.
2006: ‘Wanoux’ (Vada) cultivar released to commerce by INRA (France). ‘Arno’ and ‘Fiorente’ patented in Italy. Prince Charles plants ‘Princeton’ elms at Highgrove House.
2007: Dutch Trig® registered in Germany and Sweden. Elm Recovery Project at University of Guelph, Canada, reports bank of resistant trees. AE Newhouse and F Schrodt report on transgenic American elm trials.
2008: Active ingredient of Dutch Trig® approved on Annex I list of EU Directive 91/414/EEC.
2009: Royal Botanic Garden Edinburgh begins a program to select wych elms for innate resistance. Edinburgh’s average elm loss is 1,000 a year.
2010: Dutch Trig® registered in Canada. Forestry Commission in UK publishes Pathology Advisory Note on DED.
2011: ‘Morfeo’ cultivar released in Italy. Many ‘Princeton’ elms planted at Highgrove House in 2006 had died from DED by this year.
2012: ‘Arno’ and ‘Fiorente’ enter commerce in Italy.
2013: Field trials of genetically engineered DED-resistant American elms ongoing in New York State and North Carolina. Major DED outbreak occurs in New Zealand, particularly Kingseat Hospital area. Spanish research finds 25 resistant native elm genotypes (0.5% of those tested).
2013-Present: New DED research program initiated in the Netherlands.
2014: IOBC “Biocontrol of Plant Diseases” conference held in Uppsala, Sweden, where Joeke Postma and Helen Goossen-van de Geijn present on Dutch Trig®. ‘Ademuz’ (pure U. minor) imported into the UK and widely planted.
2016: Edinburgh City Council reports 15,000 elms.
2017: National Elm Trial (USA) final ratings published, recommending ‘New Harmony’ and ‘Princeton’ (American elm) and Morton Arboretum introductions and ‘New Horizon’ (Asian elms).
2020: The Conservation Foundation’s elm programs (‘Great British Elm Experiment’ and ‘Ulmus londinium’) discontinued.
2023: University of Minnesota’s project “Winning the Dutch elm disease battle: developing resistant elms for Minnesota” completed. Planting event with Green Crew of Izaak Walton League. Royal Botanic Garden Edinburgh raising and distributing seedlings from controlled crosses of rare survivors.
Current (2025 as per source dates): A registration for Dutch Trig® is in process in the UK. Alberta has the largest number of elms unaffected by DED in the world. Winnipeg has close to 200,000 elms, the largest surviving urban forest in North America.
Cast of Characters
Allen, M.: Author of “Urban forest advocacy in Winnipeg’s urban communities” (2002), mentioned in the context of Winnipeg’s success in managing DED.
Barendina Gerarda Spierenburg: Dutch phytopathologist who compiled records of trees displaying DED symptoms from 1900-1905 onwards in the Netherlands, publishing her findings in 1921. Her work contributed to the start of extensive DED research.
Bea Schwarz: Pioneering Dutch phytopathologist who isolated the fungus causing DED in 1921, leading to the disease being named “Dutch elm disease.”
Benjamin Held: Co-principal investigator for the “Winning the Dutch elm disease battle” project at the University of Minnesota.
Bernier, L.: Canadian researcher who conducted work on Ophiostoma ulmi mutants and differentiation of strains. Co-author on papers regarding O. ulmi and O. novo-ulmi.
Brasier, C.M.: Researcher who identified Ophiostoma novo-ulmi as the cause of the second DED pandemic (1991). Co-author on UK Forestry Commission research notes.
Christine Buisman: Dutch phytopathologist who, in the 1920s and 1930s, identified the sexual stage of the DED fungal pathogen and developed methods for experimental infections of elm seedlings, contributing to the selection of resistant trees.
D.W. French: Professor in the Department of Plant Pathology at the University of Minnesota, co-author on the guide “How to Inject Elms With Systemic Fungicides.”
Danny Rioux: Author of the paper “Dutch Elm Disease in Canada: Distribution, Impact on Urban Areas and Research.”
Don Murray: Mentioned as a personal communication regarding Fredericton’s DED management success.
E.S. Kondo: Co-editor of the “Proceedings of Dutch elm disease, symposium and workshop” (1982).
F.A. Baker: Consultant and co-author on the guide “How to Inject Elms With Systemic Fungicides.”
G.B. Ouellette: Canadian researcher who conducted light and transmission electron microscopy studies on elm defense mechanisms and the fungus itself.
Gary Johnson: Cooperator on the “Winning the Dutch elm disease battle” project at the University of Minnesota.
G.D. Huntley: Author of “The elm – A resurgent resource or a persistent problem?” (1982).
Gustafson, G.: Author of a report on DED status in Saskatchewan (2002).
Helen Goossen-van de Geijn: Co-author of the presentation “Biological Control of Dutch Elm Disease” from Plant Research International.
James L. Sherald: Researcher at Michigan State University, co-reported on genetic engineering techniques for DED-resistant American elm trees (1993). Also, author of “Elms for the Monumental Core: History and Management Plan” (2009) for the National Park Service.
Joeke Postma: Lead author of the presentation “Biological Control of Dutch Elm Disease” from Plant Research International, Wageningen University & Research.
Johanna Westerdijk: Dutch phytopathologist, under whom Bea Schwarz and Christine Buisman worked.
John Gibbs: Co-author of a 1994 Research Information Note on DED by the UK Forestry Commission.
Joan Webber: Co-author of a 1994 Research Information Note on DED by the UK Forestry Commission.
Jozef Ric: Mentioned as a personal communication regarding DED recrudescence in Toronto.
Katie Connolly: Undergraduate researcher doing soil analysis work for elm restoration at home during COVID-19 for the University of Minnesota project.
L.P. Magasi: Author of “Maritimes Region” (1982) and co-author on a report about DED in Fredericton, N.B. (1993).
Lisa Rehaluk: Grande Prairie municipal arborist, quoted on the importance of the elm pruning ban.
Mariam B. Sticklen: Researcher at Michigan State University, co-reported on genetic engineering techniques for DED-resistant American elm trees (1993).
Mark Stennes: Former graduate student and lead author on the guide “How to Inject Elms With Systemic Fungicides.”
M. Hubbes: Canadian researcher who worked on induced resistance in elms and the aggressiveness of Ceratocystis ulmi.
Oliver Rackham: Historian and botanist from Cambridge University, who presented evidence of an earlier elm disease outbreak in north-west Europe (c. 1819–1867).
Pierre Côté: Mentioned as a personal communication regarding the encouraging DED situation in Quebec City.
Pierre Jutras: Mentioned as a personal communication regarding the catastrophic DED situation in Montreal.
Rachel Carson: Biologist, author of Silent Spring, who argued for improved sanitation and against widespread DDT spraying for DED due to its environmental impact.
R. Pomerleau: Canadian researcher who reported on the first observation of DED in Canada (1945) and tracked its spread in Quebec (1953, 1961, 1964).
R.J. Scheffer: Researcher cited for work on mechanisms involved in biological control of DED (1990) and co-author on “Biological control of Dutch elm disease” (2008).
R.S. Jeng: Canadian researcher who worked on induced resistance and phytoalexin accumulation in elms.
Robert Blanchette: Cooperator on the “Winning the Dutch elm disease battle” project at the University of Minnesota.
Ron Schraven: Co-author of the presentation “Biological Control of Dutch Elm Disease” from BTL Bomendienst.
Ryan Murphy: Research fellow on the “Winning the Dutch elm disease battle” project at the University of Minnesota.
S. Takai: Canadian researcher who conducted extensive work on cerato-ulmin, a phytotoxin produced by O. ulmi.
Sophia Huang: Certified Arborist and Marketing and Education Leader at A Plus Tree, author of “How to Identify Dutch Elm Disease?”
T.R. Peace: Dr. Tom Peace of the British Forestry Commission, who began monitoring the spread of DED to the United Kingdom in the late 1920s and documented the first epidemic.
