Invasive species damage industries
By Renee Sandelowsky and Helen Varekamp
Renee Sandelowsky and Helen Varekamp are Bayfield residents and local volunteers. They are writing a monthly series of articles about the benefits of planting native species of plants and removing invasive species. This month (March 2026) they are writing about the impact of invasive plants on agriculture, forestry and fisheries.
The economic impact of invasive plants in our environment is serious business. Some people might think, “They’re just plants – how bad can they be?” Well, according to many reports, they can be bad – very bad.
Invasive plant species spread quickly. They are difficult to contain once established. The costs to control them can be staggering.
The effects are felt by all of us.
Agriculture, forestry, and fishing are some of the industries hit hardest.
Invasive Plant Impacts on Agriculture
Wheat Stem Rust is one of the most widespread and damaging diseases of wheat in Canada and the world.
The invasive shrub, Common Barberry, a host to Wheat Stem Rust, has been banned in Canada. However, while some rust-resistant cultivars are exempt from the ban, scientists are now finding their offspring are often not rust-resistant and are spreading through gardens.
Oxeye Daisy is another invasive weed that threatens to take over pastures and crops, reducing the quality and amount of food available for livestock and production of seed.
A serious invasive pest, Spotted Lanternfly, is hosted by the invasive Tree of Heaven.
Salt Cedar can lower water tables and increase soil salinity in irrigation systems.
These are just a few examples of invasive plants harming agriculture.
Invasive Plant Impacts on Forestry
About 89 per cent of invasive woody plants in our region originated in nurseries.
Invasive plants threaten our forestry industry.
Norway Maple, European Buckthorn, Black Locust, White Mulberry, Scotch Pine, invasive Honeysuckles and understory species, such as Garlic Mustard, are just a few of the invasives threatening our forests.
Some invasive plants impact carbon sequestration. Others alter soil chemistry. Some hinder forest regeneration and weaken and damage native species of trees. Trees harmed include hardwood species such as Sugar Maple, which is essential to the maple syrup industry.
Invasive Plant Impacts on Fisheries
In our freshwater bodies of water, including the Great Lakes, invasive aquatic plants degrade ecosystems. Invasive plants lead to reduced productivity and economic impacts while also decreasing water quality for recreational use.
Aquatic invasives, such as Water Lettuce and Yellow Flag Iris, grow into huge mats of vegetation and block sunlight. As a result, native species of plants die. This impacts fish and other wildlife that depend on native plants for habitat and nourishment.
Additionally, the thick vegetative mats are dangerous for boaters and swimmers and can restrict water flow for irrigation and in flood control canals.
Several invasive aquatic plants that harm fish habitat have been banned in Ontario, including Parrot’s Feather and Water Chestnut.
Manitoba has broader regulations that include Yellow Flag Iris, Water Lettuce and Water Hyacinth, to name a few. Sadly, Ontario has not regulated these three invasive aquatic plants so gardeners can still purchase them.
The evidence is clear that invasive plants from the horticultural trade impose significant costs on nature, our communities and our economy. The fact that many of these invasive species are still sold at some garden centres means we each have a responsibility to do our research and choose plants that sustain the ecosystems upon which we all depend. You too can commit to making plant choices that protect biodiversity, human health and the economy.
– Renee Sandelowsky and Helen Varekamp are Bayfield residents and local volunteers. They are writing a monthly series of articles, about the need to remove and switch away from invasive plants, for the Canadian Coalition for Invasive Plant Regulation. To learn more, visit https://ccipr.ca/