Invasive plants are costing Alberta billions of dollars each year, and experts are hoping awareness can help get more people hands-on in the fight against weeds. According to the Alberta Invasive Species Council, plants make up the largest group of invasive species in the province by both abundance and diversity. “It’s interesting, because even though we have the most of them, they are probably the least kind talked about,” said Megan Evans, executive director of the non-profit society. Invasive plants have competitive advantages that, combined with a lack of natural predators, help them push out native species and change local landscapes – costing the Alberta economy about $2 billion each year. “They change the way the ecosystem functions, they degrade natural habitats, and in agricultural lands, they reduce crop yields,” Evans said. “There’s also some invasive plants, like the invasive annual grasses …that can alter fire regimes,” she added. “Where those invasive annual grasses have established and really become problematic, they see that wildfires come through more frequently.” There are 75 regulated invasive plant species in Alberta that landowners are legally required to remove or control. Among some of the most prolific offenders, Evans said, are the Russian Olive (an ornamental tree currently overrunning river valleys in southeastern Alberta), spotted knapweed (a reproductive juggernaut that produces a toxin killing surrounding plants) and the pretty purple creeping bellflower (a herbicide-resistant ornamental with far-reaching roots undeterred even by concrete). Until 2010, the ubiquitous self-cloning dandelion was also on that list. Evans said its removal may lead some people to think it isn’t a problematic plant, but that’s far from the truth. “It’s quite to the contrary,” she said. “They’re kind of so far gone that we’ve lost the battle with dandelions, so they are incredibly invasive.” In 2015, the City of Edmonton stopped using herbicide on dandelions on public property. The city said because the plants are no longer prohibited, mowing is a better management option. “The city embraces our natural environment, and dandelions are a part of our ecosystem and are an early food source for wildlife and pollinators in the spring,” Fiona Spitzig, an invasive weed specialist, said. Evans disagrees. “Not all pollinators can forage on dandelions. That’s an important distinction,” she said. “Lots of different plant species produce flowers that bloom all season long. For our pollinators, (when) the dandelions get in there, they could potentially out compete those native species.” What to do about weeds Because battling invasive plants doesn’t always work (such as in the case of the determined dandelion), Evans said prevention and early detection are key. Evans said anything unexpectedly popping up in the garden should be identified and dug up immediately to prevent an infestation. The Alberta Invasive Species Council has a guide that can help. Other preventative measures include cleaning footwear before and after travelling, and staying vigilant when shopping, as invasive plants occasionally end up on greenhouse shelves or in wildflower mixes. “Plant swaps are another place where we relatively commonly see some of these invasive plant species,” Evans added. “If somebody shows up to a plant swap and they tell you they have so much of this plant and it just does so well … that might be a red flag.” Evans recommends planting native species, which are lower maintenance and easier to control in the long run, not to mention being a great benefit to local pollinators such as Alberta’s whopping 371 native bee species. “You start planting these native plants and you see these native bees come, and you all of a sudden have this ecosystem in your yard,” she said. “It’s so exciting.” “And,” she added, “you don’t have to worry about them becoming invasive and taking over and having another creeping bellflower disaster like we all have on our hands.” But what do you do when the weeds aren’t coming from your own yard? While complaining about dandelions won’t get you far, all other 75 prohibited weeds can be reported to the City of Edmonton by calling 311. Those calls, the city said, are investigated by staff who can then enforce bylaws and the Alberta Weed Control Act. If property owners don’t comply, city crews clean up the weeds and tack the cost onto the owner’s property tax bill. Last year, the city said it received 3,586 calls about weeds on private property and carried out 900 weed remediation jobs on private land. The City of Edmonton also has a program inviting residents out each weekend to pull weeds and learn to spot the plants causing problems in the city. “Our volunteer weed pull events give people a hands-on chance to come and learn about invasive plants, actively manage them, and it’s also a great opportunity to steward the landscape (and) the parks that we all share in Edmonton,” said city weed specialist Fiona Spitzag. On Saturday, volunteers learned about the fast-growing, infrastructure-busting Japanese Knotweed, which Spitzag said is near the top of the list of invasive species. “It’s a plant that is present in Edmonton in relatively small numbers, but it grows really quickly,” she said. “Its roots can grow through tiny cracks in concrete, and as a result, it can damage infrastructure, the foundations of homes, things like that.” The City of Edmonton will hold weed pull events at different locations every Saturday until the fall, with each session focused on different problem plants. You can find more information or register for a weed pull on the City of Edmonton website.
