Fighting Back Against Phragmites: An Invasive Threat to Grand Lake’s Wetlands

Photo credit: Samuel Freli, Wikimedia Creative Commons

At first glance, the tall, feathery plumes of phragmites may seem picturesque—but this fast-spreading perennial grass is one of the most serious threats to wetland biodiversity in eastern North America, including the sensitive ecosystems around Grand Lake.

Native to Europe and Asia, Phragmites australis (also known as common reed) has invaded wetlands across Quebec, and can be found in roadside ditches, beaches, and marshes near Grand Lake. Standing up to five metres tall, this reed quickly outcompetes native vegetation, creating thick stands that choke out local plants and wildlife.

Phragmites spreads aggressively through both wind-dispersed seeds and an extensive underground root system called rhizomes. Once established, it’s incredibly difficult to remove. Its dense growth blocks sunlight, alters water flow, and disrupts natural wetlands. Native animals suffer too—turtles can’t navigate through it, and birds struggle to find insects in its inhospitable environment.

Identifying phragmites is key to controlling its spread. Look for tall stalks with blue-green leaves that are over a centimetre wide and grow in sheaths along the stem. In late summer, phragmites produces large, fluffy flower clusters that are easy to spot.

The Grand Lake Association encourages all residents to be vigilant against phragmites. If you suspect this invasive species is growing on or near your property, please take action by following these control methods:

• Cutting/Mowing: Regular cutting can help reduce density and limit seed development, although it won’t kill the plant. Cut frequently throughout the growing season to stress the plant and prevent regrowth.

• Excavation: Hand-digging may be effective for small patches. Be sure to remove all roots and dispose of material in sealed black garbage bags left in the sunlight for 1–3 weeks—or burn. Do not compost.

• Herbicide Application: Glyphosate-based herbicides (WeatherMAX or VisionMAX) are highly effective when applied properly. Dead stalks should be removed beforehand. Note: these products cannot be applied near water.

• Burning: After herbicide treatment, a controlled burn can help to eliminate dead plant material. Burning must be done safely, with appropriate permits.

• Flooding: Where water levels can be managed, flooding phragmites with 1.5 metres or more of water for at least six weeks can drown the plants.

• Tarping: In sunny areas, cut the plants low and cover the patch with a tarp for at least six months to smother new growth. Monitor for regrowth regularly.

  
  

• Disposal: Always dispose of removed material in the garbage—not the compost. Otherwise, seeds and roots may survive and spread.

By taking proactive steps and working together, residents can help stop the spread of this invasive grass and safeguard the natural beauty and ecological health of Grand Lake.

Resources:

Phragmites brochure.pdf

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