People passionate about nature

Invasive Phragmites – a new aquatic invasive threat in Manitoba!


by Sandi Faber Routley, ISCM Project Technician

Manitoba is on early detection alert for a wetland invader recently discovered in the province called Invasive Phragmites (Phragmites australis subspecies australis). This invasive subspecies was accidentally introduced to North America in the 1700s from Europe. It is commonly confused with native Phragmites, which has a nearly worldwide distribution. The invasive subspecies has now spread throughout the United States and Canada, preferring disturbed wetland areas. Plants form thick stands which out-compete native plants, alters habitat for wildlife, changes nutrient cycling, and impacts hydrology of the land.

Invasive Phragmites (other common names: Ditch reed, giant reed, yellow cane) is a tall, semi-aquatic perennial grass that can grow to heights of 4.6 m (15 ft) or more and form dense monocultures. It has green leaves 1-4 cm (1-1.5 in) wide and 75cm (30 in) long. Unlike native Phragmites (subspecies americanus), leaf sheaths remain attached and are difficult to remove. It is also much taller than the native species and has longer, darker flowering heads. Native Phragmites has a ‘sunburn look’ to the lower stalks in the fall. Invasive Phragmites remains green and growing when all the native plants have already died-back for the winter.


Two stands were first reported to ISCM in the Winnipeg area in 2010. They were positively identified to be invasive Phragmites during initial flowering stage in August 2010. Immediate action by a few of ISCM’s Early Detection Rapid Response (EDRR) members involved removing the seed heads in attempt to prevent further spread of this invasive plant. Since that time a total of 6 sites (8 stands) have been confirmed in the Winnipeg area, and an additional 2-3 suspected sites are to be confirmed in 2011.

At ISCM’s Annual Meeting in December, a workshop on control and management of invasive Phragmites was given by Dr. Janice Gilbert, an ecologist with Ontario Parks. Dr. Gilbert is dealing with widespread infestations of this plant in Ontario. Following the December workshop, an Invasive Phragmites response team was set up for Manitoba comprised of members from ISCM, Manitoba Water Stewardship and City of Winnipeg Naturalist Services Branch. Using Dr. Gilbert’s recommendations, one invasive Phragmites ditch site in Winnipeg will be used as a test site by the response team. It is scheduled to be flattened and burned in early March 2011. Follow-up action is to occur in spring 2011, depending on water levels at the site.

Please report any suspected sightings of invasive Phragmites to ISCM at or call Manitoba Water Stewardship at 1-87-STOP AIS-0 (1-877-867-2470).