The City of Edmonton said Dutch elm disease (DED) has been detected in several trees in the Killarney and Yellowhead Corridor East neighbourhoods, marking its first appearance in the city. DED is caused by a fungus and can affect any elm tree. As of Friday, the City of Edmonton said a total of four trees have tested positive for it. “Edmontonians take great pride in our city’s urban forest,” said City of Edmonton Director of Infrastructure Operations Mark Beare in a Tuesday press release. “The detection of Dutch elm disease will understandably raise concerns, and we want to reassure Edmontonians that we have taken — and will continue to take — swift action to address the situation.”The City of Edmonton said it has activated an integrated action plan to contain the spread of DED. This work is in co-ordination with the Canadian Food Inspection Agency (CFIA), Alberta Agriculture and Irrigation, and the Society to Prevent Dutch Elm Disease. DED is caused by a fungus that is spread among elm trees through their roots and by particular species of bark beetles carrying the fungus from tree to tree. Although it is impossible to determine how it arrived in Edmonton, it is often brought to new regions through the transportation of firewood or by importing infected trees.The City of Edmonton pointed out elm trees make up 22% of its maintained tree inventory — an estimate of about 90,000 trees. In some mature neighbourhoods, it said elms comprise almost all boulevard trees.As part of a routine inspection in early August, the City of Edmonton said crews observed symptoms of DED and the first appearance of live banded elm bark beetles in American elm trees. It added samples from the trees were submitted to the Alberta Plant Health Laboratory (APHL). On August 15, results indicated the trees tested positive for DED. The CFIA was notified and sampled the positive trees on August 16. On August 27, CFIA lab results confirmed its presence. Two additional cases of it were confirmed by the APHL on August 29. All city trees that tested positive for it have been removed. At the moment, the City of Edmonton said crews are conducting visual surveys and samplings in the Killarney and Yellowhead Corridor East neighborhoods to identify any trees on properties displaying its signs and symptoms. It predicted this work will be completed by September 30.It is working with the CFIA and the Alberta government to determine the approach for all trees in these neighborhoods. To mitigate the risk of spread, it is conducting targeted elm tree removal to reduce the habitat of the beetles spreading the fungus. City-owned elms along 127 Ave. have been injected with TreeAzin Systemic Insecticide to improve their defense against insects. TreeAzin is injected into the trees and is safe for people and animals.It has acquired Arbotect 20-S, which is the industry standard fungicide for the prevention of DED. Arbotect 20-S is injected into the trees and is safe for people and animals. While DED has been identified, it said containing it takes a community effort. There are three ways residents can stop its spread. The first way is to not bring firewood from another jurisdiction. Beetles carrying it are most likely to be brought to Edmonton in firewood, so people should remember to always burn it where they buy it.The second way is to remove bark beetle habitat. This can be done by pruning elm trees between October and March to remove dead, dying, and diseased branches. The third way is by calling 311 if people see signs of DED. Its signs include wilty, droopy, or curly leaves on one or more branches from the latter half of June to the middle of July; droopy, yellow leaves dropping prematurely if the infections happen later in the summer; brown staining in the sapwood that can be seen by removing the bark of infected twigs; and beetle emergence holes the size of the diameter of a pencil lead or sawdust on the bark that indicate burrowing beetles. Beare concluded by saying the City of Edmonton’s robust, proactive approach to inspections helped to identify the first cases early and is assessing and evaluating all of the elms in the affected neighbourhoods.“Our priority is to contain the spread,” he said. The City of Edmonton warned people of the potential impacts of Dutch elm disease and emerald ash borers to its urban forest if they bring firewood from outside its boundaries in July. READ MORE: City of Edmonton asks residents to not bring in firewood because of pestsIf people plan on camping or doing leisure activities this summer, the City of Edmonton said they should not bring firewood back to the city from other communities. It added it is essential to prevent the spread of pests that could devastate about half of its boulevard and open space trees. “The main way that both Dutch elm disease and emerald ash borer spread is through the transportation of firewood from other areas with infestations,” said City of Edmonton senior scientist Mike Jenkins.
