Invasive plant species takes root in Canada

An invasive plant that has destroyed large swaths of land in the southern United States, has been discovered for the first time in Canada.
A patch of kudzu grows in Leamington, Ont., the first patch of the invasive species ever to be found in Canada. ((Sam Brinker/Ministry of Natural Resources))

An invasive plant that has destroyed large swaths of land in the southern United States has been discovered for the first time in Canada.

The patch of kudzu vine was found on a bluff overlooking Lake Erie in Leamington, Ont., a farming community about 30 kilometres southeast of Windsor.

It measures 120 metres by 50 metres and is "pretty well established" but contained, according to Rachel Gagnon, a co-ordinator with the Ontario Invasive Plant Council (OIPC).

"There's a possibility to control that spot before it starts spreading into new areas," Gagnon said.

If not destroyed immediately, the plant could wind up costing "millions of dollars to eradicate," said Rowan Sage, a biology professor at the University of Toronto, who began studying kudzu 20 years ago.

"It becomes a nuisance on land people want to be productive," Sage said. "Once it gets established in a region, it gets to be a problem."

The patch could easily be pulled out or even fed to a herd of goats, Sage said.

Aggressive growing behaviour

Kudzu is "an aggressive invader," the OIPC says in a pamphlet describing the vine, which looks like two-metre-tall bean stalk.

A close up of a kudzu leaf. The vines can grow as much as 30 centimetres a day and reach heights of 2.1 metres. ((Rachel Gagnon/Ontario Invasive Plant Council))

It grows up to 30 centimetres a day, blanketing everything in its path, including hydro poles, fences, houses and highway signs. It destroys tree species and other vegetation, the pamphlet says, "either by girdling them as it climbs, breaking them from the weight of the vines, or eventually by blanketing them and causing death by preventing photosynthesis."

Kudzu is also an alternate host for soybean rust, a pathogen that reduces crop yields.

Southern Ontario accounts for more than 66 per cent of the province's total soybean production, according to the Ontario Soybean Growers' 2008 annual report.

But the spread of kudzu is not "a major issue," according to Horst Bohner, a soybean specialist with the Ontario Ministry of Agriculture, Food and Rural Affairs, because the crop disease cannot survive the region's cold winter.

"When you have a frost like we obviously do, the rust cannot overwinter," Bohner said.

'The vine that ate the South'

Originally imported to the United States from Asia in 1876 for the World's Fair, kudzu was later planted widely along highways to prevent erosion.

In time, however, the aggressive vine invaded at least a dozen southern states, including Florida, Tennesee and parts of Texas, giving it the nickname "the vine that ate the South."

It began to migrate north and has been reported in Ohio and southern Michigan, meaning it can "clearly survive at this latitude," Sage said.

He is especially curious to know whether the kudzu growing in Leamington floated over Lake Erie from Michigan or if it was imported on purpose.

"Knowing how it got there is probably more important than it being there," he said. "It's the 'how' that will help us prevent this in the future."