You’ll see it along the roadsides, field edges and ditches across the Finger Lakes and New York State. Wild parsnip season is here, but don’t pick the flowers or leaves.
Wild parsnip (Pastinaca sativa) is an invasive species imported from Eurasia. It is unclear whether it was accidentally or intentionally brought here, but it has spread throughout parts of the United States and Canada. In this part of the country it has a biennial life cycle. The first year the plant remains a basal rosette. The large three-lobed leaves may resemble celery. The second year, the deeply grooved stem may reach 2-5 feet with hundreds of umbellate yellow flowers. The leaves look like parsnip leaves. It will slowly invade areas following the initial infestation. Once the population builds, it spreads rapidly. All those flowers produce hundreds of seeds. The umbel on the main stem flowers and sets seeds first as a survival tactic; if it gets mowed or cut during flowering, some of the seeds may be mature enough to survive. Summer heat inhibits new seed germination and cold temperatures (stratification) of winter improve germination. Several states consider wild parsnip a noxious weed. It has a fleshy taproot and, believe it or not, cultivars are grown in the vegetable garden for its roots! We don’t see flowers since it is a biennial. An Ohio extension factsheet suggests not eating the roots of wild parsnips as they look similar to poison-hemlock and grow well in similar environments. Ingestion of poison-hemlock is fatal.
Wild parsnip is one of the few weeds that can cause phyto-photo-dermititis. That means that the compounds in the sap called furocoumarins are absorbed by the skin, energized by ultraviolet rays from the sun, and cause tissues to break down in 24–48 hours. UV rays are produced on sunny or cloudy days. The skin will redden, blister and form a dark red or brown discoloration that can last up to two years. The sap is most irritating at the time of flowering which lasts June through July.
The best way to control wild parsnip is eliminating it before the population builds. Wearing gloves, long sleeves and pants, the entire top portion of the root can be cut off with a shovel.
This prevents the roots from resprouting. Any seeds produced need to be burned or sent to a landfill. Seeds may only remain viable in the soil for four years as this helps with control: persistence pays off when seed set is prevented. Poorly timed roadside mowing may increase the number of seedlings and percentage of plants surviving to maturity. Mowing allows more sunlight to reach immature plants, which are too low to be mowed. Glyphosate (Roundup) will control it in the vegetative stage. Spot apply to the rosettes. Follow label directions.
This weed is listed on New York State’s Department of Transportation’s website of Dangerous Plants. Check it out to see what other dangerous weeds lurk along our roadsides in the Finger Lakes! www.dot.ny.gov/dangerous-plants/ . Looking for more information? Contact Cornell Cooperative Extension of Yates County at 315-536-5123.