Editor’s Note: This blog was inspired by the recent South West Invasive Managers (SWIM) field tour, in which OWC’s Outreach Assistants (along with tour participants) learned about what’s being done to manage invasive weeds in our watershed.
Our watershed is a beautiful place, but land managers have long been fighting a battle against a variety of invasive weeds. There are numerous innovative methods that are being used to tackle invasive weeds in southwestern Alberta beyond hand-pulling or herbicide. Biocontrols (the use of natural enemies to combat or reduce invasive species), such as livestock and insects, have been used since the 1950s. Steam is being tested on weeds in Waterton National Park. Through ongoing research and modern technology, managers are doing what they can to control invasive weeds.
“Hello, Goodbye!” - Developing Biocontrols
The Lethbridge Research and Development Centre has been testing and releasing biocontrols for addressing leafy spurge (Euphorbia esula, listed as noxious under The Weed Control Act). Biocontrols are natural predators to the plants and are released to restore ecological balance to an area. They do not completely get rid of the weed, but rather reduce total quantities so that native species are able to repopulate. The Lethbridge Research and Development Centre has tested and released two types of beetles as biocontrols, and the results have been astounding. One that we got to see first-hand was the flea beetle, Aphthona lacertosa. We learned that it takes at least ten years of research before a biocontrol is released. Tests are done on native plants, crops, and endangered plants to ensure that the beetles won’t create an unanticipated problem, like feeding on a different species of plant. The spurge beetles are effective because the adults work to defoliate the leaves and stems above ground, while the larvae feed on the roots below ground. This two-pronged attack causes the spurge stands to be thinned quickly. Microbes, nematodes, and mites are other examples of other potential biocontrols.
“All Together Now” - Sheep and Flea Beetles
The tour also made a stop at the Waldron Ranch. For over 40 years the Waldron Ranch had been spending thousands of dollars on herbicide to try to control leafy spurge on over 65,000 acres of the historic ranch, but to no avail. Eventually, a different method was explored—sheep! The Waldron Ranch has a grazing lease with the neighboring Hutterite colony; the sheep graze early in the morning and then again in the evening when it is cool and more comfortable. Sheep are picky creatures and need to be ‘trained’ to eat spurge from older sheep so they don’t eat too much and get sick. Leafy spurge is slightly toxic in large amounts, but has the same digestible nutrition as alfalfa (Medicago sativa), which is a common food source for grazing animals.
There has been amazing progress on the ranch because of the sheep, but they don’t get to accept all of the credit; beetles are also used to control the spurge, and whatever the sheep don’t eat, the beetles will get. Sheep also act as a method of transportation for the beetles between far-to-reach patches. The beetles hop on the sheep as they walk through the spurge patch, and then hop off when they reach a new patch. Instead of spending thousands of dollars each year on herbicides, the ranch is making a small profit from the grazing lease, as well as covering wages for the herders who take care of the sheep. The extra space and forage meant that the Hutterite colony could increase the size of their sheep herd. It’s win-win (except perhaps from the perspective of the invasive spurge)!
Spraying herbicides next to a river is highly damaging to the riparian and aquatic ecosystems. To help address the issue, a new treatment method has been introduced in Waterton National Park called Aquacide. Essentially, this is a process that uses a pressure washer to scald weeds with water that can be up to 130°C. This is a relatively new method, and researchers are still learning against which weeds it is most effective. So far, Orange Hawkweed (Hieracium aurantiacum) has been the best candidate. Species with rhizomatous roots (matted roots that grow horizontally) seem to be the most affected by the treatment. There are a few downfalls to this method; it is not selective, so if there are other species growing next to a weed, they could potentially be harmed in the process. Furthermore, it is not effective on species with a tap root. However, this method could be the answer to controlling weeds along riverbanks, since it uses water and won’t harm the fish species that are present in the aquatic systems.
Weeds - “Here, There, and Everywhere”
We have looked at how invasive weeds are being tackled in our watershed, but how do they spread so quickly in the first place, and why are they bad? Here are some more readings about invasive weeds:
The Good, the Bad, and the Weedy - some of the impacts of invasive species on our watershed (blog from summer 2017)
Watershed’s Most Wanted: Invasive Weeds - get to know some common invasive weeds in our watershed (blog from summer 2018)
Weeds in Southwest Alberta: New Research Findings - collective weed management (blog from March 2017)
“It’s All Too Much” - Cumulative Effects
Like most watershed issues, invasive species can be attributed to (and in turn contribute to) cumulative effects (“changes to the environment that are caused by an action in combination with other past, present and future human actions” - CEAA). Invasive species can be introduced by wind, water, rail, livestock and/or feed, from people’s gardens, gravel, industrial equipment, tools, on people’s shoes/wheels/boats, etc. Combined with other human activities on land and water, it all adds up to spell bad news for our sensitive ecosystems. That said, thanks to human innovation, new technologies are being developed every day to combat the spread of invasive weeds.
To learn more ways to stop the spread of these invasives:
Check out the Oldman Watershed Council Facebook page and follow along with Sydney and Rebekkah as they post weekly videos identifying weeds and how to stop the spread.
Remember to clean off any gear or boots that could potentially be carrying the seeds of future invasive species.
If you would like to get your hands dirty and work alongside Rebekkah and Sydney this summer, there are weed pulls being put on throughout the season. Check out our Summer Events Blog to get the scoop about the events we will be attending!