The City of Toronto maintains planted and naturalized areas through best management practices such as forest thinning, prescribed burns and controlling invasive plant species. Those practices create healthy forests that provide many environmental benefits. Learn how you can help and what to expect when forest management operations are happening in your area.
A prescribed burn is a deliberately set and carefully controlled fire. These burns are a part of the City’s long-term management plan to restore and protect rare Black Oak woodlands and savannahs in Toronto’s High Park, South Humber Park and Lambton Park.
Prescribed grazing is the practice of using livestock to address management concerns in habitats adapted to grazing, such as meadows and prairies. Prescribed grazing can address issues such as invasive, non-native or non-compatible plant species, woody vegetation encroachment and soil improvement. The City of Toronto has piloted the use of goats for meadow management at Don Valley Brick Works Park.
Pollution, construction, erosion and other factors deteriorate our natural habitats, and invasive species take advantage of the disturbance to thrive. Invasive species compete with native plants for growing space and nutrients. Please keep in mind that invasive species management on public land is done by qualified Urban Forestry staff only.
You may need a permit to Injure or Remove a Tree.
| Plant Type | Method: Manual Control | Method: Chemical Control |
|---|---|---|
| Herbaceous Annual or Biennial
(Garlic mustard, Himalayan balsam, tall sweet white clover, burdock) |
hand pull or cut close to the base when flowering | only in extreme circumstances |
| Herbaceous Perennial
(Daylily, Dog-strangling vine, Japanese knotweed, goutweed, lily-of-the-valley, Miscanthus grasses, periwinkle, phragmites) |
|
apply herbicide using spray bottle or sponge:
|
| Woody
(Norway maple, Manitoba maple, white mulbery, English ivy, Siberian elm, white poplar, common buckthorn, winged euonymus, non-native honeysuckles, Asiatic bitterwseet,) |
|
cut stems and apply herbicide to stem |
Cosmetic use of pesticides is prohibited unless authorized by a permit from the Ministry of Environment, Conservation and Parks.
Learn about invasive insect species control.
Phragmites australis, also known as Common Reed, is a non-native perennial grass that invades wet or moist areas, growing both on land (terrestrial) and in water (aquatic). This tall grass can reach up to five metres tall, forming dense stands that outcompete native vegetation, reduce biodiversity and alter wetland ecosystems.
Phragmites has rapidly spread throughout Ontario in recent decades, forming monocultures – where nothing grows except for Phragmites – that:
Phragmites can be identified by its:
Integrated Pest Management (IPM) is an approach that combines proven strategies to manage invasive species using both chemical and non-chemical methods. The City of Toronto employs a variety of these researched and effective techniques to address the challenges posed by Phragmites.
Mechanical removal weakens Phragmites by cutting the stalks, reducing the plant’s ability to photosynthesize and depleting its energy reserves over time. This method is labour-intensive and may require multiple treatments to be effective. The two main mechanical techniques used by the City are:
Spading involves using a shovel to cut Phragmites stalks below the soil surface, limiting photosynthesis. This labour-intensive manual technique has been successfully used by the City of Toronto’s Community Stewardship Program volunteers in several sites across Toronto. It requires doing this repeatedly throughout the growing season.
This technique is used in aquatic environments, where Phragmites stalks are cut below the water’s surface to deprive the plant of oxygen and light, ultimately weakening it. Water must be at least 15 centimetres deep for this method to be effective. To enhance efficiency, machines like the Truxor amphibious cutting tool may be used.
For large, established Phragmites populations, pesticides are often the most effective management option. Any pesticide used is applied by licensed professionals who strictly adhere to all provincial and federal regulations. The pesticides used have undergone rigorous safety testing and are applied at concentrations that are effective against the target species while minimizing impact on non-target plants, animals, and aquatic life.
The City of Toronto also follows best practices for pesticide application, ensuring that treatments are conducted in a manner that minimizes risks to public health and the environment. This includes careful planning of treatment times to consider seasonal wildlife activities, monitoring weather conditions such as rain or wind to prevent drift, and placing clear signage to inform the public about areas being treated.
RoundUp WeatherPro is approved for the treatment of Phragmites on land but not approved for over-water use in Canada. The chemical glyphosate inhibits a key process in plant growth, preventing it from making essential proteins, which weakens and eventually kills the plant. This process is not found in animals or humans, which is why it has low toxicity to non-plant organisms.
Habitat Aqua is approved for the treatment of Phragmites growing in water. The chemical imazapyr works by blocking a process necessary for protein production, leading to the plant’s death. This process is not found in animals or humans, which is why it is generally considered to have low toxicity to non-plant organisms.
To apply Habitat Aqua in aquatic environments, a permit is required from the Ontario Ministry of the Environment, Conservation and Parks (MECP).
The University of Toronto is researching biological control methods to manage Phragmites long-term. Two moth species are being studied for their potential to reduce Phragmites’ competitive advantage by feeding on the plant. The City is collaborating with researchers on trial releases in specific parks. This research is still in early stages and results will be monitored to determine potential applications for the control of Phragmites.
Visit Phragmites – Ontario Invasive Plant Council for more information on Phragmites and best management practices.
Pruning of City trees will be completed according to good arboricultural standards and only if it is deemed necessary by the City.
According to good arboricultural standards, pruning is performed to:
Tree pruning is not performed to:
Download the City’s tree pruning guidelines.
Tree thinning is a selective removal of trees and shrubs from a densely planted area so that the remaining trees will have better access to growing space, light, water and other nutrients.
During a tree thinning:
Sites may look different after tree thinning.
Succession is the natural process of replacement of one group of plants by another group of plants in an area over time. Species that are more tolerant to shade will naturally replace the species that are fast-growing and less shade tolerant.
Tree thinning mimics succession. In the City of Toronto, thinning will be implemented in the areas that were densely planted with a mix of sun and shade-loving trees. Short-lived, sun-loving trees such as poplars provided habitat for the growth of long-living, shade-loving trees such as oaks and maples.
Once the long-living species become well established, the short-living species are removed to reduce the competition for growing space and promote the growth of the shade-loving species.
The Ontario Ministry of Environment, Conservation and Parks Cosmetic Pesticide Ban limits the use of pesticides by homeowners for cosmetic uses. There are exceptions for forestry management, arboriculture, health and safety, and natural resource management. Application of pesticides under these exceptions will require the services of a licensed exterminator.
The City of Toronto uses herbicides under the natural resources management exception to manage larger areas infested by aggressive invasive species that can’t be managed manually.
The City of Toronto uses two Class 9 pesticides regulated by the Pesticides Act.
Roundup Weathermax is the primary herbicide used by the City. It is considered non-toxic.
Garlon RTU is used for species that don’t respond to Roundup Weathermax. It is particularly good for roots. This herbicide can also be used in colder weather. It has a low-toxicity.
Coloured dye is mixed with the herbicides to indicate where it has been used. City staff will post signs indicating the area that has been treated. Please follow the instructions on the signs until they have been removed.
Pesticide use is regulated. Any use of pesticides (including herbicides) is prohibited in the city of Toronto and homeowners shall focus on manual methods of invasive species management.
In 2021, the City of Toronto entered into an agreement with Forests Ontario to provide source-identified native trees and shrubs for the City’s natural area planting programs. This 10-year contract will supply native source-identified trees and shrubs through the Tree Seed Diversity Program to expand nursery capacity and secure increasing amounts of plant material. This long-term agreement will allow the establishment of the required services including seed collection sources, nursery infrastructure and growing time to produce 25,000 native trees and shrubs annually.
Forests Ontario is a leader in tree planting in the province of Ontario and has extensive experience and expertise to carry out the deliverables for the Tree Seed Diversity Program. They have established relationships with a wide group of partners/subcontractor required to support comprehensive planning, seed collection, storage, stock production and delivery.
Planting trees and shrubs grown from seeds, which have been collected from appropriate climatic regions, will improve genetic diversity and support an ecosystem that is more resilient to climate change impacts. This is an important goal of the Toronto Ravine Strategy, Strategic Forest Management Plan, Biodiversity Strategy and the Toronto Green Standard.
More information about the Tree Seed Diversity Program is available on the Forests Ontario website.