GOOD NEWS! Phragmites Removal at Lynde Shores Conservation Area: Enjoy the View!

Phragmites is an incredibly invasive tall reed that grows in ditches and wet areas throughout Durham Region. It spreads quickly, forming dense stands that outcompete native vegetation and reduce wildlife habitat. Many visitors at Lynde Shores Conservation Area have noticed it spreading in the marshes and even obstructing views into Cranberry Marsh from several lookouts.

This fall, 2.5 hectares of Phragmites were treated with herbicide at Lynde Shores Conservation Area in an effort to stop the spread, protect the provincially significant wetland habitats of Lynde Creek Marsh and Cranberry Marsh, and restore the views into the wetlands. The focus was on three key areas. CLOCA partnered with Durham Region to manage the Phragmites growing along Victoria Street. This four-lane roadway crosses over Lynde Creek Marsh and is a major source of the spread of Phragmites within Lynde Shores. Additionally, a newly established population of Phragmites was treated in the Shisko Wetland (a new wetland constructed in 2021 just east of the main parking lot) as well as a 1.5-hectare patch in Cranberry Marsh.

Before and after views into Cranberry Marsh from the northeast lookout (circled in yellow on map above). View in image faces southwest.

Before and after views into Cranberry Marsh from the southwest lookout (circled in orange on map above). View in image faces southeast with Lake Ontario visible as the horizon line.

Images on the left show the views from two lookouts obscured by Phragmites (October 2025), and images on the right (December 2025) show clear views into Cranberry Marsh after herbicide treatment and dead stem removal of the Phragmites. Photo Credit: E. Kerr

Why herbicide?

Phragmites is an extremely resilient plant, and one of the most effective tools for reducing large, well-established populations is the careful, targeted use of herbicide. The glyphosate-based herbicide that was used at Lynde Shores Conservation Area has been approved for use in natural areas and has minimal impact on surrounding plants and animals when applied correctly. All herbicide applications were completed by licensed and experienced staff who have been trained in safe use and environmentally conscious techniques. Herbicide was sprayed directly onto Phragmites leaves during low-wind conditions to limit drift, and late in the growing season when most native plants and pollinators are dormant.

Phragmites spreads both by seeds and a large, underground network of rhizomes (horizontal roots) that allow it to quickly form dense patches. These rhizomes can extend several metres from the visible stems and store enough energy to regrow the plant if the above-ground portion is removed. Since so much of the plant is hidden below the surface, effective control must target both the above-ground leaves and stems and the underground root system. In the late summer and fall, Phragmites prepares for winter by moving sugars and nutrients from its leaves down to its roots and rhizomes for storage. When a systemic herbicide is applied during that process, the plant carries the herbicide down into its root system, and the herbicide kills the whole plant rather than just the above-ground portion. Fall herbicide application also avoids sensitive wildlife periods such as bird nesting, fish spawning, and amphibian breeding. As an added precaution, each patch was surveyed to ensure no wildlife were present at the time of application.

Herbicide is not intended as a long-term management strategy, but is an important first step.  When applied properly, it can be about 90 per cent effective and result in a major reduction in regrowth the following year. Once the population has been significantly reduced, CLOCA will switch to mechanical management methods, including hand spading or cut-to-drown techniques. We anticipate requiring one follow-up spray in 2026 to target any regrowth.

Why cut down the dead stems?

Phragmites stems are rigid, and dead stems can remain upright for years, continuing to block lookout views in the Marsh and limiting the space and sunlight native wetland plants need to grow. Cutting down the dead Phragmites stems also makes it easier to spot and treat any Phragmites regrowth next year.

Drone image of Truxor machine cutting down a stand of dead Phragmites stems. Photo Credit: M. Grieve

Small piles of cut stems were intentionally left in the Marsh to mimic natural features created by muskrats and other wetland animals. These piles add variability to the Marsh, offering raised spots for birds such as Red-winged Blackbirds and Marsh Wrens to perch or nest, and providing shelter for frogs, turtles, snakes, and small mammals. These simple features help restore wetland complexity and support a wider range of wildlife as the habitat recovers.

Pile of Phragmites stems in Cranberry Marsh used to create wildlife habitat mounds. Photo Credit: E. Kerr

Why is there still some Phragmites in Cranberry Marsh?

A 1-hectare patch of Phragmites was left in the northeast corner of Cranberry Marsh to support two ongoing Phragmites management research projects. These projects may contribute to future long-term, province-wide sustainable Phragmites management practices.

Patch of remaining Phragmites adjacent to the northeast lookout at Cranberry Marsh (circled in yellow on map above). View in image faces west. Photo Credit: E. Kerr

After decades of laboratory research, two European moth species have been approved for release in Canada as biocontrols of Phragmites. Both species of moths’ larvae only eat Phragmites, favouring the invasive Phragmites.  

More info on Phragmites biocontrol

In 2023, researchers from the University of Toronto released moth eggs and larvae on the eastern shore of Cranberry Marsh to investigate the impact of water conditions on the success and long-term establishment of the moths. This research is ongoing.

More info on biocontrol release at Cranberry Marsh

Additionally, researchers from the University of Waterloo are focusing on restoration planting and plan to explore what plant species may best support wetland recovery after the biocontrol becomes effective. As these studies progress, we anticipate managing the remaining Phragmites patch, or portions of it, once research goals are met.

What’s next?

Invasive species management is never one-and-done. Phragmites is a highly persistent plant, and initial management typically takes a few years to complete, followed by continued monitoring to prevent re-establishment. After the follow-up herbicide treatment in 2026, CLOCA’s natural heritage staff will continuously monitor and mechanically remove Phragmites across Lynde Shores Conservation Area.

Central Lake Ontario Conservation Authority is committed to improving the health of these wetlands for the plants, animals, and people that rely on them, and we can’t wait to see the positive changes unfold in 2026 and beyond!

This project was made possible through funding from the Invasive Species Centre and the Ontario Phragmites Action Program as the administrators of the Invasive Phragmites Control Fund. Thank you to Durham Region for partnering with us to remove the Phragmites along Victoria Street, and to the Invasive Phragmites Control Centre for their expertise and implementation efforts!