Originally published in Native Plant Society of Saskatchewan newsletter. Portion of original article by Chet Neufeld, NPSS Executive Director
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 (Lythrum salicaria) 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 was 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. Every year in August, the wetland is mapped to determine the current waterline as well as the extent of the spread of flowering rush. At the same time, plant counts and other data are collected, photos are taken and all flowering rush are manually removed using protocol developed by the NPSS.
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).
*Author’s note: An additional Flowering Rush population was found in 2016 in east-central Saskatchewan in a dugout, and eradication efforts were immediately implemented by local authorities. It is expected that this population will be eradicated within a few years.
The NPSS received confirmation of additional populations of Flowering Rush on the shores of the South Saskatchewan River near the Saskatchewan-Alberta border which was initially reported in 2016. Nicole Kimmel, a Weed Specialist with Alberta Agriculture and Forestry, confirmed the population along the South Saskatchewan River in Saskatchewan while conducting a survey of Flowering Rush that started on the Alberta portion of the river and leads into Saskatchewan as she followed the infestation. She observed several hundred locations of Flowering Rush in the Saskatchewan portion of the South Saskatchewan River before she had to turn back. There are undoubtedly more Flowering Rush plants further downstream in Saskatchewan from where Nicole turned back, and the NPSS, the Saskatchewan Invasive Species Council, and relevant stakeholders have met to discuss the next steps for this worrying development. There are plans to map the full extent of Flowering Rush in the Saskatchewan portion of the South Saskatchewan River and control options are being discussed, but eradication is likely not feasible given the size of the population and the threats of reinfestation from upstream in Alberta (Nicole surveyed 500 km of the Bow and South Saskatchewan Rivers and found 3970 locations of Flowering Rush). Nicole had this to say: “These numbers are a devastating blow to any plan we had in mind for the area. This is significantly higher than we anticipated. We are still brainstorming control ideas, but our eradication hope has definitely been challenged.” Even containing it to the South Saskatchewan River basin or portions thereof would at least help keep the rest of Saskatchewan’s aquatic habitats safe. We will continue to work with Alberta to coordinate our efforts.