Society to Prevent Dutch Elm Disease

Join STOPDED to help foster and promote the survival of the American elm in Alberta.

Winnipeg street before Dutch Elm Disease (Photos: Mike Allen, former City of Winnipeg forester)

Winnipeg street after Dutch Elm Disease

Dutch Elm Disease Awareness Week

Dutch Elm Disease Awareness Week is recognized annually throughout Alberta from June 22 to 28. Read our Agri-News article: Help protect Alberta’s beautiful elm trees.


The Society To Prevent Dutch Elm Disease (STOPDED) is a non-profit organization. Its mandate is to foster and promote the survival of the American elm (Ulmus americana) in Alberta, and to protect Alberta’s landscape trees threatened by pests with emphasis on invasive alien species.

Members include federal, provincial and municipal representatives, nurserymen, landscapers, commercial and municipal arborists, research scientists, and other interested Albertans. STOPDED members from across the province take an active role in the prevention of Dutch Elm Disease (DED) in Alberta and in their communities.


Under Canada’s Plant Protection Act, Plant Protection Regulations, the movement of both DED pathogens is regulated. Elms from a DED-infected province cannot be shipped to a disease-free province. Alberta and British Columbia are classified as DED-free.

Under the Alberta Agricultural Pests Act (APA) Pest and Nuisance Control Regulation, both DED pathogens (Ophiostoma ulmi and Ophiostoma nova ulmi) – and the European and native elm bark beetles that carry them – are named declared pests. The Alberta government supports this critical effort by administering the act and regulation which provides the means to enforce the DED prevention and control measures.

Under the act and regulation, all municipalities, counties and municipal districts in Alberta have the responsibility and authority to prevent and control DED. All municipalities are encouraged to implement the Alberta Dutch Elm Disease Response Plan.

STOPDED is responsible for operating the Provincial DED Prevention Program. Along with all the larger cities, the society operates a full program which includes public awareness focussed on preventing the establishment of DED in Alberta. The society also monitors for the elm bark beetles that carry the disease in many municipalities, nurseries, provincial parks and at all the Alberta and US ports of entry. Firewood is confiscated at all the ports of entry and placed in bins. STOPDED arranges to have the wood collected and disposed of. STOPDED is also involved with arranging to have suspect DED samples taken properly and sent to the lab for diagnosis.

The society is also involved with trapping and public awareness on the Emerald ash borer. Emerald ash borer is a species of metallic wood-boring beetle native to East Asia. Ash trees are very vulnerable to this beetle, which has killed millions of trees in eastern Canada in forested and urban areas. In 2017, the borer was found in Winnipeg for the first time. It has not been found in Alberta or Saskatchewan.

Funds generated from membership dues and fundraisers are used to provide educational and promotional materials on DED prevention. STOPDED depends on public support and participation in their ongoing prevention program.

Board members

ChairpersonAlexandra Pepperdine, City of Calgary – IPM Technician
Past ChairpersonMichael Jenkins, City of Edmonton – Pest Coordinator Animal Care & Pest Management
Vice ChairpersonScott Stanley, City of St. Albert – Tree Services Team Lead
SecretaryJacqueline Powell, Red Deer Regional Hospital – Nurseryman #1
TreasurerChristine Kelly, City of Red Deer – Ecological Service Technician
DirectorSarah McPike, City of Edmonton – Biological Sciences Technologist
DirectorJeff Quinlan, City of Medicine Hat Parks & Recreation Department – Technician
DirectorLindsay Bell, City of Lethbridge – Urban Forestry Technician

Why it's important

Elm tree populations in Alberta are subject to numerous stresses. The most serious threat comes from DED, a fatal fungal disease that infects only elm trees. DED moves rapidly from infected to weakened trees on the bodies of European, banded or native elm bark beetles. The disease can kill an individual tree in as little as 3 weeks. The whole population of elms in a community can easily be destroyed within a decade.

Currently, Alberta and British Columbia are the last 2 locations in North America that are free of DED. However, in 1998 one elm tree in Wainwright was confirmed to have the disease. The tree was immediately removed and burned. This tree was noticed to have typical DED symptoms by STOPDED employees while completing the provincewide elm inventory survey.

In July 2020, the City of Lethbridge had 2 elm trees that tested positive for DED at Agriculture and Forestry’s Alberta Plant Health Lab. The trees were immediately removed and city staff surveyed all elms trees for DED symptoms and elm firewood in the area where the diseased elms were found. This detection is considered an isolated case at this time, and eradication was successful.

Since 1994, the European elm bark beetle has been found throughout the province. In 2006, the banded elm bark beetle (BEBB) was first found in Medicine Hat. Since then, the numbers of BEBB have increased substantially throughout the city. BEBB are now found in low numbers in municipalities across the province.

Find out more about Dutch elm disease and what you can do to help.

Provincial elm tree inventory

A site-specific tree species inventory supplies the basic information necessary for an effective tree pest’s prevention or management program. The information also identifies areas where more intensive monitoring and surveillance are necessary due to the number or condition of the tree species threatened by a pest. Knowing the value of each tree species is important in order to justify a prevention and management program.

In March 1999, STOPDED published its first provincewide elm inventory in Alberta cities, towns, villages and hamlets, a project that took 2 years to complete.

In order to complete the inventory, the province was divided into DED management regions. A region included a municipality that currently had a DED prevention program in place, with a number of municipalities in their buffer zone. Regions included Edmonton, Strathcona County, Red Deer, Calgary, Lethbridge, Medicine Hat and Brooks.

The method used to access the value of the elm trees – the trunk formula method – was developed by the Council of Tree and Landscapes Appraisers and is used by the International Society of Arboriculture. The valuation method used for the inventory was updated in 2017 to reflect an increase in the value of the trees. This valuation research was done by Mumby’s Arboriculture Consulting.

2017 inventory results

The 2017 elm tree inventory indicated that up to 50% of the overall tree plantings in many municipal landscapes are elms. It was found that there was a 35% increase in the municipal elm value over an 18-year time period. See full 2017 Elm Tree Inventory data.

Table 1. Overview of 2017 Alberta elm tree inventory

Table note: not all cities have updated their 1999 inventory elm numbers or values.
LocationsTotal elmsTotal elm values
Communities – excluding 17 cities95,973$334,402,510
Cities – 17 in Alberta193,903$643,743,938
Total elms: communities and cities289,876$978,149,448

See our latest: Dutch Elm Disease Survey Report – October 18, 2021.


Help support these activities by becoming a STOPDED member. Fill out and mail in a membership form:

STOPDED membership form


See all DED forms and documents.


To report suspect DED symptoms or for more information, call:

STOPDED Hotline 1-877-837-ELMS (3567)

For compliance and enforcement issues, contact your local municipality or Agricultural Fieldman.