Now is the best time to eliminate giant hogweed, an Asian plant that was brought to North America about a century ago.
It is currently spreading throughout southern Ontario. It has been found on several GRCA properties near Belwood Lake, St. Jacobs, Kitchener, Guelph, and Cambridge.
The GRCA has a program to eliminate giant hogweed from its properties, but it is a persistent species that is difficult to permanently remove.
If anyone sees some on private land or in an unmarked area, such as along a riverbank or stream, contact the local municipal weed inspector.
Wellington County weed inspectors are:
– north, Angelo Giovinazzo, 519-853-8722; and
– south, John Benham, 519-846-0941
If anyone sees giant hogweed on a GRCA property such as a conservation area or other signed and marked properties, contact the GRCA’s operations department at 519-621-2761.
Hogweed can suffocate local vegetation and cause a serious health risk to people who come into contact with it. The sap will make a person’s skin extremely sensitive to sunlight – causing severe burns and blisters. That sensitivity can last for years – and the plant is capable of causing death in extreme cases.
By August, hogweed stands out because it grows more than four metres tall, but in May it is shorter and 30cm in diameter.
It is a member of the carrot or parsley family and its stem has purple blotches and is intensely hairy.
The leaves are very large and jagged. It is easily confused with cow parsnip, angelica, and water hemlock.
The GRCA has created a fact sheet to assist with identification. That can be found in the Forestry section of the GRCA website under Invasive Species.
Giant hogweed is a perennial weed, meaning the same plant will grow for more than two years. New plants are established only from seed. What is unique about giant hogweed is that it flowers and produces seed only once in its lifetime, according to research done in the Guelph area. Once it has produced seed, the plant dies.
Therefore the strategy for limiting the spread and movement of giant hogweed is to stop seed production.
GRCA staff dig out the plants each spring, but in most cases new plants will grow up each year from seeds.
The GRCA does not own or manage all river and stream banks.
Most banks are privately owned therefore it is the responsibility of the landowner and the municipality to take action against hogweed on private land.
A fact sheet and videos to help identify and control giant hogweed posted on www.ontarioinvasiveplants.ca.
