The agriculture and agri-food sectors are key economic drivers in Canada, employing 2.3 million people and generating $150 billion annually (Agriculture and Agri-Food Canada, 2024). Supported by Greenbelt Foundation and stewardship, Ontario’s Greenbelt contributes $9.6 billion annually to Ontario’s GDP, supports 177,700 full-time or full-time equivalent jobs, and provides Ontario communities with $3.2 billion worth of ecosystem services each year. Some examples of ecosystem services include flood mitigation, air and water quality improvement (carbon sequestration, waste/nutrient regulation), biodiversity/wildlife habitat, recreation and tourism, climate change mitigation (temperature regulation), and soil formation and retention.  

While these systems are important for economic growth, they can also have profound impacts on public health, food security, and environmental sustainability.

Preventing the spread of invasive species will help protect our agricultural industry.

Impacts of Invasive Species

Lower Crop Yields
Reduced Crop Quality
Restrict Foraging Space
Disrupt Ecosystem Services
Lower Property Values
Increase Operational Costs 
Vector Other Insect Diseases
Damage Infrastructure
Harm Humans, Livestock, and Wildlife

There are different types of invasives that cause economic harm in Canada. For example, invasive plants, such as witchweed and woolly cup grass, that grow in crops and pastures are estimated to cost $2.2 billion each year in damages (CFIA, 2021). Invasive insects, like European cherry fruit fly, are estimated to cost North America about $27 billion each year and affect agriculture the most (Crystal-Ornelas, 2021). These annual losses are expected to worsen over time with climate change. Many invasives will thrive under warmer conditions, expanding their range and becoming more difficult to treat.

Dodders (Cuscuta spp.) are parasitic weeds that wrap around host plants, absorbing their water and nutrients. Dodder infestations can inhibit growth for many agricultural crops, such as tomatoes (reducing yields up to 75%) and carrots (reducing yields up to 90%; Dechassa & Regassa, 2021).

Some invasives can introduce other pathogens. Common buckthorn is a deciduous woody shrub that dominates disturbed areas like fence lines, pastures, and open fields. It can host oat crown rust and soybean aphid, both of which reduce crop yields. Kudzu, a perennial climbing vine that forms dense mats over other vegetation, is an alternative host for soybean rust and kudzu bug. These pests spread alongside kudzu, threatening soybeans and other legumes.

Spotted lanternfly (SLF) are invasive planthoppers that feed on economically important plants, such as grape vines and maple trees. Infestations of SLF in New York State are a direct threat to Ontario’s adjacent Niagara Peninsula, which accounts for 80% of Canada’s total grape and wine production (Deloitte, 2023). It’s estimated that this industry is worth $5.9 billion in Ontario alone (Wine Growers Ontario, 2019).

Leafy spurge is an herbaceous plant that produces toxic sap, which can cause skin irritations in humans and serious illness for cattle and other wildlife. Leafy spurge has spread rapidly in Canada since its introduction in the 1800s, displacing native vegetation and reducing foraging capacity. It’s estimated to cost more than $30 million each year to manage and contain this invasive plant in Manitoba alone (OIPC, 2024).

There’s been a steady rise in glyphosate-resistant weeds over time, making invasive plants like waterhemp and lamb’s quarter more difficult to treat. The increase in herbicide use and decrease in crop yields are estimated to cost Canadian growers up to $1.5 billion annually (OMAFRA, 2020).

Japanese beetles feed heavily on the foliage and fruit of over 300 ornamental and agricultural plants. It’s estimated to cost more than $460 million a year to control in the United States (USDA, 2015).

Case Study: Potato Wart in Prince Edward Island

Potatoes are the primary cash crop for Prince Edward Island, contributing over $1.3 billion annually to the provincial economy (Government of Prince Edward Island, 2020). These high-quality potatoes were infected with a soil-borne fungus called potato wart for the first time in 2000, causing major concerns for producers. This invasive fungus can deform potato tubers, reducing yields and marketability by 50-100% (CFIA, 2023). As a result, U.S. imports of fresh PEI potatoes were closed for six months. Potato wart has been an ongoing issue for the province since its initial discovery, periodically interrupting domestic and international trade. For example, PEI farmers were forced to destroy about 300 million pounds of surplus potatoes in 2022, and the United States Department of Agriculture’s Animal and Plant Health Inspection Service (AHPIS) introduced new import restrictions in an attempt to prevent the spread of potato wart (CFIA, 2022).

Protect Canada’s agriculture industry by following clean equipment protocols; providing training on the identification, signs, and impacts of invasive species; and getting involved in sustainable practices.

Have you seen an invasive species? Report it at invasivespeciescentre.ca/report-a-sighting!

Get Involved

Canadian Food Inspection Agency: Cuscuta citizen science project

References

Additional Resources

Ontario Invasive Plant Council: Clean Equipment Protocol

Photo Credits

Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org

Utah State University, Bugwood.org

John D. Byrd, Mississippi State University, Bugwood.org

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