A new invasive insect has found its way to Edmonton’s Killarney and Yellowhead Corridor East neighbourhoods.
The elm zigzag sawfly, named for the distinctive zigzag pattern its caterpillars chew in elm leaves, was sighted in Edmonton.
As of Friday, four threes have tested positive for Dutch elm disease, the city said in a news release Tuesday. As a result, Edmonton activated a plan to contain its spread.
All city-owned trees that tested positive for the disease have been removed.
Earlier in July, the City of Edmonton asked residents to not bring firewood from other communities back into the city.
As part of a routine inspection in early August, city crews observed symptoms of Dutch elm disease, along with the first appearance of live banded elm bark beetles in American elm trees. Samples were sent for testing to Alberta Plant Health Laboratory.
“The city’s robust and proactive approach to inspections helped to identify the first cases early and we are currently assessing and evaluating all of the elms in the impacted neighbourhoods,” said Mark Beare, director of infrastructure operations. “Our priority is to contain the spread. We will continue to take swift action to address the situation.”
There are around 90,000 elm trees in Edmonton – 22 per cent of trees in the city.
City crews are conducting visual surveys and samplings in Killarney and Yellowhead Corridor East neighbourhoods to identify trees displaying signs and symptoms of the disease. This work is estimated to be completed by Sept. 30.
City crews are also conducting targeted elm tree removal to reduce the habitat of the beetles that spread the fungus.
What is Dutch elm disease
Dutch elm disease is caused by a fungus that is spread among elm trees through their roots and by specific species of bark beetles that carry the fungus from tree to tree. Although it is not possible to determine how the disease arrived in Edmonton, it is often brought to new regions by the transport of firewood or by importing infected trees.
What residents can do
Beetles that carry Dutch elm disease are most likely to be brought to Edmonton in firewood, so remember to always “burn it where you buy it.” Residents can also prune elm trees between October and March to remove dead, dying and diseased branches. Do not combine elm wood with food scraps or other collected waste.