Flowering rush (Butomus umbellatus) is an exotic, invasive plant that was sold for use in water gardening up until the summer of 2010, but is now prohibited by law in Saskatchewan. Its invasive characteristics are similar to the better-known purple loosestrife in that it invades wetland edges and slowly displaces native species, forming a monoculture and ultimately killing the wetland.
In 2002, a single population was found in a wetland in Saskatchewan but remained largely unknown until 2008. This is the first and only known escaped population of flowering rush that has established in Saskatchewan. Recognizing the danger of letting it spread to other nearby wetlands, the NPSS launched a project to map and eradicate the flowering rush in this wetland. In 2008 and 2009, the wetland was mapped to determine the extent of the spread of flowering rush. At the same time, vegetation and other data were collected, and the flowering heads of the flowering rush were clipped, bagged and burned to prevent seed dispersing. However, since flowering rush also spreads by rhizomes (creeping roots), the plants themselves had to be removed. In 2010, manual removal of the flowering rush plants began. Thanks to good volunteer turnout, approximately half of the flowering rush population was removed and the rest of the population had the flowering heads clipped to prevent seed spread. We also developed a protocol for manual removal of flowering rush, the first of its kind.
In 2011, most of the remaining flowering rush was removed by October. We also monitored the areas where flowering rush was previously removed to ensure that it didn't re-emerge. We found the previous year's removal efforts very effective as roughly only 25% re-emerged. These were promptly removed. This rate of success is very good and proves that the manual removal protocol that we developed is effective. In fact, Alberta is now using our protocol for some of its own flowering rush removal. By the end of 2011, only 5% of the original flowering rush population remained, which will be removed in 2012. The wetland was re-mapped and other nearby wetlands were searched in order ensure that flowering rush had not spread.
In 2012, manual removal started in August and continued until the remaining 5% of the original plants and any that reemerged from the previous year were removed. The site was also a tour stop for the Pacific Northwest Economic Region (PNWER) Invasive Species Committee as a model of an effective early detection and rapid response project. PNWER is an international organization (of which Saskatchewan is a member) and had their annual meeting in Saskatoon in 2012.
For 2013, the site was resurveyed to determine how many plants had reemerged, and also to re-map the wetland. Where flowering rush had received more than one year of removal, it was quite sparse and was easily removed again. Where the flowering rush had only been removed in 2012 for the first time, the patches were denser, the plants more vigorous, and it was as difficult to remove as the first time. 2013 is the first year that the flowering rush has put up a good fight. While the back of the wetland (which is the newest and least infested) is showing real progress, including complete eradication of whole areas, the front of the wetland along the road (the oldest and most entrenched flowering rush populations) is showing the least progress, though progress is still being made. By the end of 2013, all of the flowering rush will once again be removed and the site will be monitored in future years and any reemerging plants will be removed.
It is estimated that by the end of 2015, all parts of the wetland except for the area along the road should be flowering rush free, and only a few patches should remain along the road which will hopefully be eradicated by 2017. This is still ahead of our initial timeline for eradication within 10 years (2020) of the first manual removal efforts.
If eradication of flowering rush is successful in this wetland, it will be one of the first successful early detection, rapid response and eradication efforts against a new invasive species in Saskatchewan (and one of the first in Canada as well).
Thank-you to the following organizations for their generous financial contribution to this project in past years: Environment Canada (Invasive Alien Species Partnership Program and the Environmental Damages Fund) and the Saskatchewan Ministry of Environment (Fish and Wildlife Development Fund).
Funding for this project in 2013 has been provided by Agriculture and Agri-Food Canada through the Canadian Agricultural Adaptation Program (CAAP). In Saskatchewan, this program is delivered by the Agriculture Council of Saskatchewan.
Many of our native grasses are able to send down roots several meters deep, making them extremely drought tolerant.