New Legislation for Invasive Plant Management in Ontario


The Invasive Species Act will come into effect on November 3rd, but the regulations associated with this legislation which have not yet been made public, will not take effect until a later date. Kellie Sherman, Coordinator, Ontario Invasive Plant Council joined the October 17th Council meeting to outline the growing threat of invasive plants in the province which has triggered this new piece of provincial legislation developed to ward off the persistent challenge presented by invasive plants which threaten our lakes, rivers and forests.

An invasive plant is an unwelcome transplant of foreign origin whose spread threatens the environment, the economy or society at large. Because they are imported from another location, they often face no natural enemies, allowing them to spread rapidly, replacing native species. These plants represent one of the most significant cause of species extinction worldwide, second only to habitat loss. Ontario has the unfortunate honour of facing the highest number of invasive plant species in all of Canada: 441 in total. It also is at higher risk of new invasions due in part to its extensive urbanized areas, its geographic location and significant sections of degraded habitats. Sherman came to urge the municipality to begin to plan a local attack on invasive plants.

The implications of the proliferation of invasive plants are broad. First, they degrade natural areas stealing light, moisture and nutrients from native species and destroying natural habitat and air/water filtration processes provided by natural areas. In agricultural settings, invasive plants may threaten crops by extending existing crop diseases or introducing new ones, reducing crop yields and triggering increased pesticide use. In reforestation projects, more aggressive species compete with new tree seedlings, change soil chemistry and in some cases create dense mats of vegetation which prevents natural forest regeneration. Preventing the spread of invasive species comes with a serious price tag for land owners and managers. For example, pilot projects operating in Ontario to prevent the spread of Phragmites (looks like Pampas grass) which can invade and disrupt municipal drain systems come with costs in the area of $1000 per hectare.

Some invasions are quite localized. The Trent River is the only wild location in North America which is home to a particularly nasty aquatic plant called Water Soldier, an ornamental plant found in water gardens. It creates a dense mat of vegetation crowding out local species, and with the power to alter surrounding water chemistry; it can reduce plant biodiversity and can harm other aquatic organisms and hinder recreational activities.   It resembles an aloe plant but is armed with sharp serrated leaf edges, which can cut swimmers and anyone handling it.

As some of the largest land managers in Ontario, municipalities and Conservation Authorities are urged to develop tools to prevent the introduction and spreading of the most dangerous species, which requires signification education for their staff and the public at large. Sherman explained that early detection is critical in the effective elimination of these pesky plants. Once established, they are very difficult (and expensive) to remove.


While the legislation is new, the threat is not. The Ontario Invasive Plant Council was formed in 2007 to provide a coordinated provincial response to the growing threat of invasive plants, and includes representatives from government, academia, industry and indigenous groups. Working closely with the Ministry of Natural Resources and Forestry and the Ontario Federation of Anglers and Hunters, their objective is to assist landowners, particularly municipalities, to develop effective strategies to curb the spread of invasive plant species.

The first step in any plant management strategy is plant identification education.   Landowners are encouraged to prevent the spread of unwanted species by controlling them on their own properties, but to do so they need effective tools. Users of public recreational areas including the Millbrook Valley Trails should be aware of existing threats in that area, including dog strangling vine, and take precautions to avoid its spread.

OPIC is encouraging early detection and a proactive approach to managing invasive species to prevent the establishment of new infestations. This requires early detection, rapid response and ongoing monitoring and reassessment of vulnerable areas. To learn more about invasive species in Ontario, visit, to find details on how to identify and remove these threats to our natural environment. KG

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