Phragmites (pronounced “frag-MY-tees”) is a perennial wetland grass which forms dense, near monoculture stands. Stems typically grow to 2 to 6 metres. It has a hollow stem, stiff wide leaves and large plumy flowers. It is native to Eurasia and was likely introduced more than once to North America in the 1800s along the Atlantic coast, as both a seed contaminant in soil ballast and intentionally introduced through the horticulture trade. Rapid expansion of this plant occurred during the 1990s and it has since spread throughout Ontario.
It prefers standing water found in wetlands, banks, lakeshores, beaches, and wet fields, however it can survive in low water areas as well. Phragmites can spread via the seeds, rhizomes and stolons, but most commonly spreads to new areas by rhizome growth and fragmentation. Mature plants can produce thousands of seeds annually.
Why are they a concern?
These stands of phragmites displace most other native plants, animals and birds within an area. The negative impacts of invasive species are second only to the destruction of natural habitats as the leading cause of biodiversity loss.
What is the City doing?
High levels of phragmites are present in Professor’s Lake.
Parks staff have consulted with industry experts on the removal of the plants from the lake, as well as seeking the Ministry’s approval to apply a foliar spray. The control of the plant is not a short-term approach and must be revisited yearly to effectively remove this plant from the lake.
The removal/spraying of this plant must be timed so that does not interfere with the nesting migratory birds, breeding times for fish and reptiles. Parks staff are currently exploring a timeline of September 2022 for spraying of Phragmites with the manual removal of the plant in November.
Control methods
- Chemical: There has been recent approval of a foliar spray called “Habitat Aqua” that allows a municipality to spray the plant over water. Any application of this product must be approved by the Ministry of Environment, Conservation and Parks (MECP), The Department of Fisheries (DFO) and City prior to spraying. Once the plant is sprayed, the dead plant material must be removed.
- Manual: Selective cutting of phragmites beneath the waterline can effectively drown the plant by inhibiting the supply of oxygen to lower plant parts. In suitable water depths, after cutting has occurred, new shoots cannot successfully reach the surface to collect oxygen. This method can be applied at small and large scales using handheld tools or amphibious cutting vehicles to cut stems.
What can residents do?
- Do not cut the plant above the ground as it encourages more root growth and the chemical spray requires a mature seed producing plant to be effective.
- Do remove seed heads and dispose of the seed heads in the garbage.
- Do not place in compost bins as the seed will be blown by the wind and spread.
- When leaving an area containing phragmites, brush off clothing and clean equipment.
Have questions?
If you suspect phragmites near your property, contact 3-1-1, and Parks staff will follow-up on next steps.