Dog-strangling vine (DSV) does not strangle dogs, but it does strangle plants and trees and can quickly overtake native plants to become the dominant plant in any ecosystem.
Native to Eurasia, DSV is a member of the milkweed family that was introduced to the northeastern United States in the 1800s for use in gardens.
In recent years, this aggressive perennial vine has spread rapidly throughout central and southern Ontario, and has been creeping into Leaside for a while now.
Kathy Gerry brought this alarming matter to my attention and said, “I’m concerned that it will become so established in our neighbourhood that we will be forever battling it!”
Kathy has been living in Leaside for 42 years. She’s an avid gardener who has transitioned her own garden to mostly native plants. She also happens to have a keen eye for spotting DSV.
“I was walking along Redway Rd., where I saw a tangled mess of DSV covering part of the sidewalk. As I checked north of that, I could see it developing colonies closer to nearby houses. That was several years ago,” she told me.
Over the past few years, she’s noticed more and more of these plants edging in at the border of a garden, or growing up through bushes in neglected gardens, and clumping along laneways where it seems to go unnoticed. This year, she has seen the invader as far north as Eglinton!
Kathy digs it up, but says that “it’s a difficult task. The roots can go down six or more inches, and if you don’t get them all, the remnants can sprout a new plant.”
The sap is also toxic, and Kathy developed a rash on her forearms. Now she wears long sleeves and double gloves when handling this nasty plant.
Cutting DSV down at the base can help weaken the plant, and a friend of Kathy’s successfully eradicated a patch by covering the vines with newspaper for a season.
In the fall and winter, the long bean-shaped pods crack open, and the wind spreads the delicate seeds far and wide. Remarkably, this plant can produce up to 2,400 seeds per square metre. So, at the very least, the seed heads should be removed, sealed in a black garbage bag, and left in the sun to bake for three weeks. Then, as with every invasive plant, they should be disposed of in the garbage, not in yard waste where they can continue to spread.
I was deeply touched when Kathy said: “The saddest part of all, for me, was trying to shoo away a monarch butterfly that wanted to lay eggs on this plant. There were no true milkweeds around. I chased the butterfly, but it was faster than me. All of those wasted eggs! They couldn’t survive on that vine.”
What can Leaside gardeners do?
Like Kathy, learn to recognize this plant at every stage of its development. Be vigilant in your own garden, take action as soon as you spot this invader. Let’s keep Leaside safe from Darth Invaders!
For more info about DSV and other green “thugs,” visit Ontario’s Invading Species Awareness Program at: https://www.invadingspecies.com.
