Public Safety Warning: Giant Hogweed聽is a public safety hazard due to its caustic sap. Do NOT go near or touch the plant under any circumstances. Due to this plant鈥檚 hazardous nature, it is highly recommended that private landowners hire a professional exterminator to remove the plant, to ensure safe procedures are followed.

Invasive Species and Diseases

Invasive species are non-native plants, animals, or diseases that spread quickly and can harm the environment, economy, or human health. Many introduced species, like corn, wheat, and garden plants, coexist peacefully, but others outcompete native species and disrupt ecosystems.

Non-native species can come from other countries or regions in Canada. Some are familiar, corn and wheat, in our food, lily of the valley in gardens, or European starlings at bird feeders. About 27% of southern Ontario’s species are non-native, and most live in balance with local wildlife.

Problems arise when a non-native species spreads aggressively and becomes invasive. These species often arrive by accident, through global trade, travel, or recreational activities like boating and gardening.

Examples: Zebra Mussels arrived in the Great Lakes in hip ballast water and have spread via boats, while pests like the Emerald Ash Borer and Spongy Moth threaten local forests.

Why They’re a Problem

Invasive species can:

  • Take over natural habitats and form monocultures that crowd out native plants
  • Cause erosion and damage soil health by disrupting beneficial fungi
  • Reduce food and shelter for native wildlife
  • Hybridize with native species, weakening their genetic diversity.

Once established, these species are difficult to remove, they spread rapidly, produce large quantities of seed, and often lack natural predators.

Common Invasive Species in Ontario

Plants

Wildlife

Diseases

Prevention and Control

The best defense is prevention. Avoid planting invasive species in gardens or near natural areas, and be cautious when purchasing soil or nursery plants. Research unfamiliar plants before buying, many invasives are still sold commercially.

If invasive plants are already on your property, act early. Control methods depend on the species and location:

Manual or Mechanical Controls

An effective control method can depend on a number of factors such as location, species and life cycle. Some species may need two or more control methods and persistence to bring under control.

  • Pulling – Hand pulling throughout the growing season can weaken the plant鈥檚 root reserves. Ensure that all parts of the root are removed or it may re-sprout.
  • Cutting – Cutting works well with annual weeds. Remove the flowering parts so that it does not produce seeds and spread.
  • Girdling – Remove a strip of bark 3 inches wide around the circumference of the tree or shrub to cut off its supply of food and water. Girdle near the ground to minimize suckering.
  • Smothering – This method involves covering the area so that no light or moisture can reach the soil, thus killing the plant (e.g., lay several sheets of newsprint of black plastic over a weedy patch).
  • Burning – Regular burning can control some early growing weeds and help encourage the growth of native species. This method is particularly useful for prairie habitats.

Chemical Control (Last Resort)

Chemical control should be used as a last resort for hard-to-control or persistent species. Round-up鈩� can be spot applied to herbaceous plants to kill their roots. Non-toxic products are also available (e.g., Scott鈥檚 Eco-clear鈩� is a vinegar-based product).