The Struggle to Choke Dog-Strangling Vine

Forests Ontario's experts, known collectively as "Silvie" (short for silviculture) answer your forestry questions. Write to info@forestsontario.ca

Dear Silvie,
I started to notice a patch of vines growing in my forest’s understory a couple years ago. The small patch has grown so much it is alarming. A friend suggested it was Dog Strangling Vine. How do I know for sure and what should I do if it is?
–PERPLEXED IN PRINCE EDWARD COUNTY.

DEAR PERPLEXED IN PRINCE EDWARD COUNTY,
There is an ongoing battle between landowners and the infamous invasive species Dog Strangling Vine (DSV). Invasive plants risk throwing an entire ecosystem off its natural trajectory; as a result, we must take their menacing actions seriously.

What is Dog Strangling Vine?
DSV appeared in Ontario gardens in the mid-1800s. It grows in open sunny areas, but also thrives on partially shaded sites. This ferocious vine distinctly grows in dense patches that can ‘strangle’ plants and small trees (not dogs). One plant produces thousands of seeds that the wind can carry to a new site, and it can also grow from root fragments left in the soil, making it challenging for landowners to control.

Identifying DSV
DSV can grow one to two metres in height with leaves between five to ten centimeters in length. The oval leaves come to a point at the tip and each leaf pair sits opposite of the other along the stem. These perennial plant leaves are green, with a shiny gloss in the early summer that fades to yellow in late summer. From late May to mid-July, it has flowers with five pink- or maroon-coloured petals about five to nine millimeters in length. The plant's bean-shaped pods grow in pairs; they start forming in July and split open by late summer to release white fluffy seeds.

Treating DSV
The best defense for landowners, farmers, and community members to reduce labour, cost, and environmental destruction associated with DSV is early detection. If it is new, or in a small area, manually and mechanically removing the entire plant, including the roots, may work to control this harmful weed. Frequently mowing DSV can help reduce seed production and population overtime. If the DSV is on inaccessible terrain, or has already formed a large dense patch, call a forestry professional.
The good news is that researchers are exploring a new weapon to help combat DSV – a moth from Ukraine. Since 2013, Ontario has had trial releases of the moth’s caterpillars. It only eats the DSV leaves, posing no threat to native plants. Over the past few years, forestry researchers in Dr. Sandy Smith’s lab at the University of Toronto have bred and studied these moths in their caterpillar stage. With promising results so far, long-term research is ongoing to better understand the moth and the role it can play in combating DSV in Ontario.

Yours, Silvie

Photo courtesy iNaturalist user Dustin Minialoff