Invasive species crews fighting corridor-wide battle 

Focus in Whistler is on Yellow Flag Iris, Japanese Knotweed

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Many battles in the long war against invasive species are being fought in Sea to Sky this summer, with crews from the Sea to Sky Invasive Species Council going after some of the worst offenders.

For Whistler that has meant continuing the battle against Japanese Knotweed, an aggressive and extremely hard to destroy plant that can damage foundations of buildings and other infrastructure, and that can regenerate itself from a single sliver of root matter. As well, the SSISC has opened a new front against a wetland plant, the Yellow Flag Iris.

"That's a big one because it was mistakenly planted here by a number of different people, and it spreads abundantly and has a really deep root system that makes it difficult to remove," said Nicolette Richer of the SSISC. "What you have to do is try to get it before it goes to seed, remove all the leaves and stems and try to get the roots out... you try to dig up as much of the root system as possible but in two or three feet of water that's difficult to do."

If you keep hacking away at the plant and preventing the spread of seeds over a period of years, Richer said the plant will eventually die.

It's a long process, she said, but that's nothing unusual in her field.

"It is a long-time commitment for invasive species management, some seeds from invasive species can sit there dormant for years before sprouting," she said.

And in the case of plants like Yellow Flag Iris, the seeds can travel down waterways and cover a huge amount of ground in a short period of time. What also makes it a priority is the fact that it has no natural predators and can take over a wetland and swamp in a few years, displacing the plants that other species of animals depend on. "It overtakes everything," said Richer.

Richer is encouraging people to download a new Report-a-Weed BC app that lets people photograph and map data on plants they've seen, and compare their pictures to other pictures in the database. The results of that data collection are shared with groups liked the SSISC, which takes action on the ground to limit their spread.

The Yellow Flag Iris has been pulled from areas that include the man-made waterway behind the Whistler Public Library and the wetlands around the Montebello development.

Knotweed is also an ongoing concern in Whistler, and crews have attacked a few plants this year.

Richer says controlling invasive species in Whistler is aided by the climate, while things are more serious in Squamish and Pemberton.

"In Squamish, Giant Hogweed is a huge concern and any time there is a sighting we will go in and remove it," she said.

Hogweed is unique among invasive species in that it can actually harm people, oozing a sap that reacts with sunlight to cause serious burns to skin. There have been cases of blindness reported in Europe as a result of exposure.

Another major concern is Japanese Knotweed. "It's overtaken the estuary in Squamish," said Richer. "The photos are astounding, if you go there you can see that nothing else is growing there.

"Along the highways Scotch Broom is a big one, and another one we've noticed recently is Orange Hawkweed. We're trying to prevent it from making its way up into the alpine, but we can see it creeping up the mountains and along the highway, in ditches and on private land."

Pemberton also has similar plants, along with burdock, which is of special concern to farmers. Chamomile is also spreading.

Richer says it's important to stay on top of these species and to involve the public and contractors like landscapers wherever possible. "We do need funding, and one of the things that's getting municipalities on board and recognizing that it's a significant issue is the fact that its already costing municipalities billions of dollars a year, and the agricultural loss and economic loss is significant.... We need a budget set aside to destroy these species and control the ones that can't be eradicated."

For more on the Sea to Sky Invasive Species Council, visit The website has information on various invasive species and programs that are available.



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