Giant Hogweed

Recently, there have been sporadic confirmed sightings of Giant Hogweed across York Region. Residents are reminded to take caution around Giant Hogweed as it can pose a health risk.

What is Giant Hogweed?

Giant Hogweed is an invasive plant that is a member of the parsley family. It looks similar to cow parsnip or Queen Anne's Lace. It is a large perennial plant that in the summer can reach heights between 15 and 20 feet (5 metres). The stem of the plant is hollow with dark reddish-purple spots and course white hairs. The leaves of the plant can grow up to five feet in width and have hairs on the underside. The plant also produces large flower head clusters.

Does Giant Hogweed pose a health concern?

Yes. If you see Giant Hogweed, DO NOT TOUCH IT. Contact with the clear and watery sap contained in Giant Hogweed stem, leaves and bristles can cause a skin reaction (rash and blistering) that sensitizes skin to sunlight. Reactions can occur up to 48 hours after contact and result in severe burns and blisters. The blisters can develop into purple and black scars. Depending on individual sensitivity, effects can last for months and skin can remain sensitive to UV light for years.

Sap contact with the eyes can sometimes cause temporary, and rarely, permanent blindness. Contact with any part of the Giant Hogweed plant should be avoided at all times.

Note: Pets can also carry the Giant Hogweed toxins on their fur. Be cautious about where your pets roam, especially in areas where Giant Hogweed has been identified.

What should you do if you have come in contact with Giant Hogweed?

If you think you have come in contact with Giant Hogweed wash affected areas immediately, keep the affected area out of the sun and seek medical attention.

What should you do if you find Giant Hogweed on your property?

• Property owners should exercise extreme caution and have the plant removed
• Confirm the identification using the resources listed below
• Hire a licensed professional pesticide/herbicide applicator to take the appropriate action to remove the plants and appropriately dispose of them

What should you do if you find Giant Hogweed in a local park or other public space?

• Immediately notify your municipality or local Conservation Authority

Resources:

Ministry of Agriculture and Rural Affairs:
Videos on how to identify and remove Giant Hogweed
Giant Hogweed in Ontario
Plants You Don't Want to Touch!

Agriculture and Agri-Food Canada
Ontario Weeds
Online weed identification services

Ontario Federation of Anglers and Hunters (OFAH)/Ministry of Natural Resources
Invasive Species Hotline: 1 800-563-7711 or www.invadingspecies.com

Nottawasaga Valley Conservation Authority
Giant Hogweed Fact Sheet