The Town of Port McNeill Council learned more about the specifics of knotweed eradication at their June 15 meeting. Mike Desrochers of Strategic Natural Resource Consultants gave an overview of the knotweed problem and provided Council with further information about how the invasive species can be treated and eventually removed.
Desrochers first noticed knotweed when he moved to the area in 1996. “The degree of the problem has become quite alarming,” he said, telling Council that the mechanism that brings the best results is injecting the knotweed with herbicide consistently until it dies. Glyphosate will be used initially, but if genetic resistance occurs other herbicides like triclopyr could be used.
Some invasive species are treated with burning; Desrochers says that burning is not a solution with knotweed as the root systems can go down seven metres with rhizomes spreading out 20 feet. Burning would be a band-aid.
One reason knotweed can grow so out of control is that it does not have any natural predators, and it has extremely effective germination. Even a 1/4 of an inch of the plant dropped on the ground will germinate, meaning that when homeowners cut and dispose of knotweed, it just grows where they dump it. The problem is not as dire in Port McNeill as in Port Hardy and Coal Harbour, where Desrochers says it could take decades to wipe out the plant. A major concern with knotweed is that it is strong enough to damage sewer systems and roads, and can even begin growing through walls into the interiors of homes.
“That sales pitch doesn’t really go good with me,” Councillor Graham MacDonald said to Desrochers. MacDonald told the group he had researched the herbicide the eradication process planned to use and had found an extensive list of countries where the chemical was banned. He went onto say that on Haida Gwaii they have been using saltwater to kill knotweed.
Desrochers and other council members said saltwater can work, but at the same time it also kills a lot of the surrounding nutrients in the soil. Desrocher acknowledged that there are drawbacks to chemical use, but said that it is important to let trained professionals deal with the problem so that uneducated vigilantes do not take it into their own hands.
“You’ve actually answered our request,” Mayor Shirley Ackland said, thanking Desrochers for the information.