Concrete-breaking Japanese knotweed sprouting in Alberta

A plant that can crumble wallsand break through concrete foundation is starting to putdown rootsin Alberta.

• Destructive Japanese knotweed sprouting in Canada
• Invasive plant that can undermine home foundations
• Oystershell scale spreading through Calgary hedges

According to the Alberta Invasive Species Council, Japanese knotweedwasspotted three timesthis spring oncein Leduc and twicein Calgary. In the past,it's also been identifiedin five other areas of the province:

• GrandPrairie
• Parkland County
• Sylvan Lake
• Trochu
• Waterton

'Tip of the iceberg'

That may not seem like too much tohandle,butthe executive director of theAlberta Invasive Species Councilsays it's nota good sign.

I've seen itgo under roads and come up through the pavement.- Barry Gibbs,Alberta Invasive Species Council

"It'susually the tip ofthe iceberg," said Barry Gibbs.

"Usually, the ones we know about are only a small proportion of the ones that are actually out there," he said.

Gibbs, who is also theco-chair ofthe Canadian Council on Invasive Species,says unlike Japan,the country it originated in,Japanese knotweedhas no natural predators in Canada.

He says it hasa "powerful" and "far reaching"root system that can grow three metres deep and up to seven metres away from the plant.

"I've seen itgo under roads and come up through the pavement."

In Britain, Japanese knotweedhas been wreaking havoc for years andcan actually bringdown property values.

"What occurs is the person trying to sell the property has no knotweed on their property but it's growing from an adjoining property into theirs," said Mark Haywood,withBritain'sNational Association of Estate Agents told CBC Radio'sThe Current.

"They can't sell their property and may approach the neighbour to help pay for it to be eradicated," he said.

Eradicating thedreaded weed

"It shouldn't be dug up. That's the worst thing you can do," said Gibbs.

That's becausethe rootsmultiply whenyou rip them out of the ground.

Gibbs says if you think youhave Japanese knotweed in your yard or garden, don't try dealing with it on your own call in a professional.

"The most effective thing we'vefound right now is to use herbicide and it'sinjected into the stem and itrequires specialized equipment that most people don't have."

Gibbs says you should also notify the City of Calgary through 311 if you spot theinvasive species anywhere in the city.