Plants around a tree log.

Neighbourhood Watch

Be on the lookout! Invasive species can have detrimental effects on natural areas and our own yards. Anyone who has tried to remove goutweed from their gardens or lost an ash tree because of emerald ash borer knows firsthand the damage an invasive species can do.
With climate change, it may be easier for new species to take hold in our watershed and cause ecological damage. Here are a few invasive species to keep an eye out for in your neighbourhood and actions you can take to protect your yard.

Jumping worms – Amynthas spp., Metaphire spp., Pheretima spp.

  • What to look for: Adult jumping worms are most likely to be seen in August and September. They’re smooth, glossy earthworms with a pale ring (clitellum) that encircles the body. When disturbed they thrash around erratically. Their feces is courser than the soil and resembles coffee grounds.
  • Why are they a concern: Jumping worms out-compete other worms, including other non-native earth worms. They break down the topsoil layer faster than other worms, changing the soil structure and reducing the capacity of the soil to hold water. This can lead to increased soil erosion. They also alter the nutrient composition of the soil which impacts what plants are able to grow and survive.
  • What you can do: Jumping worms can be introduced to new areas by moving soil with eggs or live worms. Don’t move soil, mulch, or plants from other areas or yards to help prevent their spread.
  • Are they in the watershed: Yes, some reports of jumping worms have been confirmed in Mississauga.

Oak Wilt – Bretziella fagacearum

  • What to look for: Discoloured leaves starting at the top of oak trees that may drop prematurely. Fungal mats form under the bark and have a fruity smell. These mats may cause large cracks in trees and large branches.
  • Why is it a concern: Oak wilt can kill a healthy oak within 2 to 12 months following infection.
  • What you can do: The fungus can be spread by beetles feeding on fungal mats and move to healthy trees with fresh cuts or wounds like those from pruning or breakage. Oaks trees should only be pruned once leaves have dropped in the fall and before spring growth to help prevent the spread of oak wilt. Additionally, don’t move firewood, as it could contain fungal spores. The fungus can also move through connected roots.
  • Is it in the watershed: Not yet, but it’s close. In 2023 it was found in Niagara-on-the-Lake, Niagara Falls and Springwater near Barrie.

Hardy Kiwi – Actinidia arguta

  • What to look for: Hardy kiwi is a woody vine that can climb trees and shrubs, creating large mats of vegetation that can strangle and smother other vegetation. The vines have simple alternating toothed leaves with red stalks. Small white flowers bloom in the early summer that form into grape-sized fruit similar to kiwi with smooth green skin.
  • Why are they a concern: The vines can strangle other plants as they twine around them and the weight of multiple vines can pull down large trees. They out-compete native plants, creating patches of monoculture in a natural area.
  • What you can do: Avoid planting hardy kiwi. If you think it may be growing nearby, early detection is key. Hardy kiwi is becoming a popular fruit to grow in agricultural settings and for the home gardener. Raccoons and other small mammals eat the fruit, then the seeds pass through their digestive system and can be deposited into natural areas.
  • Is it in the watershed: Yes, there have been two reports. One was found in a nature reserve in Caledon where the source plant was identified in someone’s yard. A second plant was found in Brampton, just north of Eldorado Park.

If you find any of these invasive species, or others, please report your observation to our Invasives Team or EDDMapS. Oak wilt can be directly reported to the Canadian Food Inspection Agency. This type of citizen science is used by people such as land managers, conservation biologists and CVC staff to understand the spread of invasive species and to help protect our natural areas.

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