What is a noxious weed, and why care about it?

Pearl Lorentzen
Lakeside Leader

For the last while, The Leader has been monitoring an outbreak of Himalayan balsam, a prohibited noxious weed, near a waterway in Slave Lake. The Town of Slave Lake parks people have pulled the plants at least twice this year, but it has returned. The Leader has also added an “It’s a Weed” feature which highlights noxious and prohibited noxious weeds in the Lesser Slave Lake area.

Under the Alberta Weed Control Act, noxious weeds must be controlled and prohibited noxious weeds must be destroyed.

“Prohibited noxious species must be eradicated by landowners,” says the Alberta Invasive Species Council website. “They are non-native with currently restricted or local distribution in Alberta that present risks of spreading and causing significant economic or ecological impact.”

Himalayan balsam can cause ecological damage to waterways, says its abinvasives.ca fact sheet. As a large shady plant with attractive flowers, it can stop native plants from growing and pollinating. Also, its shallow root system can increase erosion. Seeds soaked in water can survive up to two years. As of July 2015, there were patches in waterways in Edmonton, Red Deer, and Parkland County.

As of July 29, there were 48 positive infestations in Alberta on eddmaps.org/alberta/. This does not include the one in Slave Lake, which wasn’t been reported into this system. It was discovered last year.

The abinvasives.ca fact sheet says this plant is on many lists of invasive species. As the name suggests, Himalayan balsam is from the western Himalayas, in Asia. It is listed as an invasive species in Europe, Asia, North America, and New Zealand.

Two tools which can be used to learn about noxious weeds are the fact sheets on abinvasives.ca and the EDDMap app (Early Detection & Distribution Mapping System). This app allows people to report noxious and prohibited noxious weeds and add to citizen science about weed locations.

The interface isn’t great for learning about weeds as the photos are very small, but once a suspected weed is found a photo is sent to an expert who identifies the weed and contacts the relevant branch of government.
Garry Roth, Town of Slave Lake Director of Community Services, is in charge of the parks department.

“From our perspective, it’s good,” says Roth about EDDMap, because all sightings are verified before they are reported to the town. This means the parks staff can be efficient in responding because they know what they are looking for. So far this year, the town has received about 10 reports from EDDMap. Last year, it received around 40 to 50 reports.

Reports are also put onto a North America-wide map at eddmaps.org/alberta/. The number of weeds reported varies. One example of a well-known easily identifiable noxious weed is the Canada thistle. As of July 21 at 2:30 p.m. the map had 213,695 records for Canada thistle in Canada and the US. Of these, 203,688 are positive, 5,270 were treated, 88 eradicated, and 4,649 were negative.

This weed is especially common in ditches.

Within the Slave Lake area, there were 37 in the town of Slave Lake, two on the road past Mr. Mikes, two on Highway 88 near Devonshire Beach, six on Highway 88 further north, and eight in the ditches of Township Rd 742. Lawrence Lake Provincial Park had three positive and two treated sightings. By Flatbush, Chain Lakes Provincial Recreation Area also had one positive and one treated sighting. This is just one of many noxious and prohibited noxious weeds in Alberta.

Himalayan balsam, still growing by the creek in Slave Lake last week after three attempts to eradicate it this year alone.
White cockle

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