Japanese knotweed may look nice, but you don’t want it growing on your property, or anywhere else for that matter.
Unfortunately, this invasive species, also known as false bamboo, has established a foothold throughout the regional district, from the Shuswap to Revelstoke and beyond.
This is a concern for Salmon Arm resident and gardener Bert Revel, who has seen and studied what can happen when Japanese knotweed is allowed to get out of hand.
“Four years ago I went to Nova Scotia by train. And Montreal to Halifax and the whole railway property line was covered with it,” said Revel. “I’d seen it in different places and knew a little bit about it. And it made me a little bit aware of it.”
Since then, Revel has been busy learning about knotweed and the troubles it has created in the UK, where the plant’s rapid spread has had a large social and economic impact.
Residential properties have been rendered unsalable because of the weed, which can grow through concrete foundations. There have also been cases where banks have refused to loan money or provide mortgages relating to properties where knotweed has taken route. The cost to eradicate the destructive weed in the UK is estimated at $1.5 billion.
Not wanting to see things come to that in Salmon Arm, Revel has been working voluntarily with the Columbia Shuswap Invasive Species Society (CSISS), mapping all the locations in the city where knotweed is growing.
There are currently 64 known knotweed sites in Salmon Arm, 14 of which are on municipal property.
“It’s all very good to come along and say where are they, let’s compile an inventory of it,” said Revel. “If you know where it is, you know how bad it is, why isn’t something being done about it while it’s small?”
Recently, Revel and CSISS program manager Robyn Hooper met with City of Salmon Arm staff to provide the knotweed inventory and discuss mitigation.
Engineering and public works director Rob Niewenhuizen said council has increased the budget for the city’s noxious weed program for 2016, when a contractor will be hired to treat those 14 patches of knotweed, as well as another invasive species, blueweed.
Where knotweed is growing on private property, CSISS will be taking the lead in terms of outreach.
“They actually have talked to some of the private owners already and explained to them how to get rid of it, and where it is and what it is,” said Niewenhuizen. “I think for most people it is education. They look in their garden and see this nice bush and they don’t realize it’s a noxious weed.”
Salmon Arm’s approach to treatment will likely be herbicide, which is allowed for noxious weeds in the city’s bylaw. It’s also one of the most economically feasible options, as knotweed’s root system can grow to a depth of nine feet. While mechanical removal is possible, the plant can quickly and easily regenerate from cuttings.
With treatment, Hooper says you have to weigh the cost and benefits of each approach, and also consider restoration and monitoring in order to restore a site to its original biodiversity.
In addition to Salmon Arm, Hooper says CSISS has been working with the municipalities of Sicamous and Revelstoke, and is developing strategies for land-owner outreach.
“We‘ve responded to some reports, but we’re still building our database as to where all the knotweed is, and then some targeted outreach,” said Hooper.
More information and resources regarding knotweed and other invasive species can be found at http://columbiashuswapinvasives.org.