How teams in the Hamilton area are fighting dog-strangling vine and other invasive species

Don't worry. Dog-strangling vines aren't actually strangling dogs.

But Derissa Vincentini, community science co-ordinator at the Invasive Species Centre in Sault Ste. Marie, Ont., said the invasive vine — which officials found in new locations in Norfolk County this past summer — is still concerning. 

"They do invade a wide range of habitats, from forests to fields and all the way up to prairies. And in doing so, they can out-compete our native vegetation and our native plants," Vincentini said. 

The perennial vines, which belong to the milkweed family, also produce chemicals, which enter soil and inhibit native plant growth.

The Invasive Species Centre provides resources and education to help monitor and control invasive plants and animals throughout the province. Dog-strangling vine is just one of many such species in the Hamilton area. Others include a self-cloning crayfish, a tall reed and an insect that targets hemlock trees.

Norfolk County's supervisor of forestry, Adam Biddle, told CBC Hamilton that dog-strangling vine has been known to exist in that region for several years. Around June, officials found it on a residential lot near Waterford, one of the county's communities. The county then found it on five residential properties within the same block in Simcoe and on a rural woodlot in the area. 

"It's not well established here. It's kind of just showing up," Biddle said, adding the goal is to "eradicate it early" before it's too late.

"It's very possible it could snowball beyond our capabilities."

According to the Ontario Ministry of Natural Resources' website, the plant can produce up to 2,400 seeds per square metre. The seeds spread in the wind and new plants can grow from fragments of roots, "making it difficult to destroy." 

Vincentini said the name "dog-strangling vine" actually refers to two species: the black swallowwort and pale swallowwort — both are restricted under Ontario's Invasive Species Act and Weed Control Act. The vine has been in the province for more than 100 years, Vincentini said, and continues to spread to new locations, aided by development and the transfer of soil and building products containing the plant's seeds.

As a municipality, Biddle said, the county doesn't typically control invasive species on private land. The county has some ability to compel landowners to remove regulated weeds, but in the case of dog-strangling vine, Biddle said it's been simplest to get landowner permission for municipal crews to pull it out or use herbicide to kill it. 

He said Norfolk County works with local conservation groups and land trusts to respond to species in the region, such as Japanese knotweed and wild parsnip. 

Biddle added that county officials are talking with partners about how to deal with invasive species on private land, which is important given more than 80 per cent of the wood lots in his area are privately owned and uncontrolled species could spread from them. 

At Royal Botanical Gardens (RBG) in Burlington, Ont., working with a range of partners is also key to managing invasive species, said the gardens' director of science, David Galbraith.