Phragmites: The Great Invasion

Paige Bissonnette – Conservation Technician

Phragmites australis seed head in winter.
[This article appears in the December 2019/January 2020 issue of The SCOOP.]

European common reed (Phragmites australis), typically referred to as phragmites, is a perennial grass invading Ontario’s wetlands, beaches, and roadsides. Phragmites, a non-native plant introduced to Canada from Eurasia in the 1800s, has spread from Nova Scotia to British Columbia.

What does Phragmites look like?
Phragmites shoots resemble bamboo with long slender stems growing up to or exceeding five meters. The seed head consists of a dense, long silky flower with approximately 2,000 seeds.

How does Phragmites spread?
Phragmites can spread rapidly and grow dense colonies over 200 stems per square metre, out-competing native vegetation. Although phragmites typically grows along water bodies, the long, dense root system of large colonies of phragmites allows for the exploitation of dryer habitats such as roadsides. Most notably, you may have noticed dense stands of phragmites along the 401 corridor.

Phragmites spreads through seed dispersal and through the spread of rhizomes and stolons that break off from the root and get transported to other habitats. Growing along waterbodies provides a dispersal advantage, as seeds and rhizomes can be transported downstream by flowing water. Phragmites can also get caught on boat motors, which allows for the accidental spread to other waterbodies.

Why should we care?
Dense monocultures of phragmites can crowd out native vegetation by blocking sunlight and taking up space that native plants need to flourish. Native vegetation is needed to provide food and habitat for many species-at-risk such as turtles, amphibians, and spawning fish. Although phragmites occupies large areas, there is no evidence to suggest that the stands provide habitat or food for marsh-nesting birds or the insects that birds need to eat to survive and reproduce.

Phragmites can also alter the hydrology of the waterbody it grows next to. Phragmites uptakes and respires large quantities of water which results in lower water levels or clogged drainage ditches.

What is being done to stop the spread of phragmites?
Managing phragmites is far from straightforward. A combination of techniques and a lot of time is needed to rid a single population. Herbicide application is the most effective control method, however caution is needed in spraying near water bodies and pesticide use is regulated so you need to be trained and licensed to apply them. Mechanical methods of removal such as mowing and/or cutting, compression rolling, and hand pulling can be effective but are not always effective by themselves and you must take care to ensure root fragments and seeds are not transported elsewhere. These methods are labour intensive, especially for large stands. Typically, an integrated management approach is needed, combining multiple techniques to most effectively manage the population. An extensive understanding of the population of phragmites in question and the surrounding habitat is needed to make an informed decision on how to best manage the population.

What can we do?
The best place to start is to learn to identify phragmites properly to reduce its spread and refuse to buy or plant phragmites. If you find phragmites on your property, report your sighting and all other sightings of phragmites to www.eddmaps.org/Ontario and then make a plan for controlling it. You can learn more management techniques by reviewing the Best Management practices here: www.ontarioinvasiveplants.ca/wpcontent/uploads/2016/07/Phragmites_BMP_FINAL.pdf.

Another way to help manage the spread of phragmites is to get out there and volunteer! Recently, Friends of the Salmon River held a volunteer event at Beaver Lake Park to educate the public on phragmites best management practices and did some hands-on stewardship. Keep an eye out for more local events to do your part in managing this invasive species.

Phragmites australis in the Great Lakes. (Photo by Elizabeth Banda/NASA)

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