Giant Hogweed, Poison Ivy, and Wild Parsnip
There is an ongoing problem in many areas of Canada with persons being injured through contact with the Wild Parsnip weed. The prolific spread and dense growth of Wild Parsnip throughout Eastern Ontario in recent years is seriously escalating this health risk in the United Counties of Leeds & Grenville.
Wild parsnip is of concern because humans develop a severe skin irritation from contact with sap from the plant. Wild Parsnip plants have chemicals called psoralens (more precisely, furocoumarins) that cause phyto-photodermatitis: an interaction between plants (phyto) and light (photo) that induce skin (derm) inflammation (itis). Once the furocoumarins are absorbed by the skin, they are energized by UV light on both sunny and cloudy days. They then bind to DNA and cell membranes, destroying cells and skin.
Wild Parsnip burns usually occur in streaks and elongated spots, reflecting where a damaged leaf or stem moved across the skin before exposure to sunlight. If the sap gets into the eyes, it may cause temporary or permanent blindness.
During much of July, August and early September wild parsnip is one of the most visible yellow-flowered weeds in roadside ditches, public recreation areas, around sports fields, fence rows, and along railroad tracks. It is also present on many residential properties throughout the county. Information to assist in identifying wild parsnip can be found on the online weed identification service at www.weedinfo.ca.
The best way to control wild parsnip is by early detection and eradication. Removing a small or new infestation early will prevent a much larger problem from developing. Regardless of the method used, the goal is to prevent the plants from seeding.
Wild Parsnip Eradication Options
Hand Pulling: The best control is achieved mainly through hand-pulling. Although this method will kill the plant, it is not practical for large infestations. Flowering plants have stout stems and may be pulled easiest after a good rain or during a drought when the root shrinks. If seeds are ripening, remove pulled plants from the area to avoid spreading the seeds; they may still ripen even after the plant is uprooted!
Digging: To dig out wild parsnip, use a narrow shovel, spade or trowel to loosen and uproot the plant. You may also slice the taproot with a sharp shovel an inch below the root crown and pull up the top of the plant. This method should be undertaken before the plant has reached a stage where it has produced viable seeds. If the plant has produced viable seeds this method may still be used but the above ground part of the plant should be removed from the area and burned. It should not re-sprout if this approach is used.
Mowing: Mowing can be an effective control method against wild parsnip, but timing is critical. Poorly timed mowing can increase the number of seedlings and the percentage of plants surviving to maturity. The best way to control the spread of wild parsnip and keep it at bay is to mow or “weed eat” it just when the flower buds are beginning to show (somewhere between end of June and beginning of July). To mow or use the weed eater later in the season actually may contribute to spreading the seeds and therefore the increase and spread of the wild parsnip population.
Note: Whatever method you use to remove wild parsnip it is necessary to wear protective clothing
How To Avoid Wild Parsnip Burns
- Become familiar with the wild parsnip plant and know it by sight.
- Teach children to recognize wild parsnip.
- Teach children at an early age of the potential danger of poisonous plants
- Discourage children from picking wild flowers.
- When working around wild parsnip wear goggles, rubber gloves, rubber boots and coveralls. Thoroughly wash boots and gloves with soap, water and a scrub brush before taking off your protective clothing.
Being able to readily identify wild parsnip and early detection of infested areas will minimize inadvertent exposure to this plant and the painful results that follow. Anyone having information on specific locations where this weed is posing a public risk should contact your municipality.
Information has been provided by Larry Sudds Weed Inspector, United Counties of Leeds and Grenville.
Here are some images to help you identify wild parsnip:
(Click on an image for a larger preview)