Edmonton is on the verge of an Elmdemic

Update Four new cases of Dutch Elm Disease confirmed in Edmonton Aug 1 →

The story so far

1 Edmonton is on the verge of an Elmdemic You're here
2 Four new cases of Dutch Elm Disease confirmed in Edmonton Aug 1, 2026

Let me tell you a scary story. It goes like this: Edmonton loses most of its 90,000 mature elm trees.

Scared? Good. It might not be a story much longer.

Here's a before and after of a street in Winnipeg.

That's what Dutch elm disease does. Once one tree gets infected, all the elms around it get removed too.

After 50 years of fighting, Winnipeg is losing thousands of trees a year. Since 2016, they've lost more than 33,000 elms. That's enough trees to line roughly 330 city blocks.

It's here now

Edmonton used to have the largest stand of disease-free elms on earth. In 2024, that ended with our first case.

We're now up to our 10th confirmed case of Dutch elm disease, found last week in Calder. That's three new cases in a month.

The city's protocol now is to remove the infected tree and every elm within 20 metres, and closely monitor everything within a kilometre.

We also have a province-wide pruning ban from April 1st to September 30th. This is because elm bark beetles breed beneath dead and dying elm wood, and when the adults fly off, they carry fungal spores to healthy trees. Those spores clog trees' water systems and can kill them in as little as three weeks.

A fresh-cut tree smells just like a stressed tree. The beetles' favourite. So summer pruning is a bit like cracking a bag of Cheetos on 4/20.

The storms don't follow the pruning ban

All across the city, we can see elms split in two, with boughs piled haphazardly on boulevards. This is like a buffet for the beetles.

Calgary is sending forestry crews up on a mutual aid agreement to help us out, but this is a big city, with 90,000 elms on public land alone.

Our mature neighbourhoods have these beautiful streets where the canopy closes into a tunnel every summer, which is exactly what people love about elms. It's why we planted them.

They've been growing for the better part of a century, and they can't be replaced in my lifetime. That's the stakes.

Because all of us remember what happens when that one unmasked guy starts coughing his contagions all over everyone else in the grocery store.

Elmdemic.

Part 2 · Aug 1, 2026 Four new cases of Dutch Elm Disease confirmed in Edmonton We've got four new cases. I remember back in early 2020 waiting with trepidation for the latest case updates. That feeling's back. Keep reading →