Everyone can get it. Unlike poison ivy, you don’t need to be sensitized by a prior exposure. Wild parsnip causes a non-allergic dermatitis that can occur with the right combination of plant juice and sunlight exposure afterwards. The burn and blister will develop in 24 to 48 hours.
You can touch and brush against the plant — carefully — without harm. Parsnip is only dangerous when the juice gets on skin from broken leaves or stems. Fair-skinned people, however, may be extra-sensitive to tiny amounts of juice. It leaves a brown mark which blisters and then a scar the size of the blister.
Some say Wild parsnip’s “burn” is less irritating than poison ivy’s “itch.” The burn from parsnip may not last as long as poison ivy, but can be at least as painful as poison ivy.
Life history: Wild parsnip typically lives for two to four years. The first year, as a spindly rosette of leaves, it keeps fairly low to the ground while the plant’s carrot-like taproot develops. It may live two or more years this way until conditions are right for flowering. The final year, a hollow, grooved flower stalk rises 2-5 feet high, first holding clusters of yellow flowers and later dozens of flat, oval seeds.
Leaves: Pinnately compound, with a main stem and 5 to 15 leaflets.
Flowers: Yellow, in flat-topped umbrella-like clusters at the top of the plant.
Season: Wild parsnip rosettes are among the first plants to become green in spring, and its flowers turn a prominent yellow in midsummer. After flowering and going to seed, plants die and turn brown in fall, but first year rosettes remain green until frost.
Habitat: Roadsides, abandoned fields, unmowed pastures, edges of woods, prairie restorations.
Elimination: There is good success obtained by cutting the root of the plant 1 – 2” below ground, being careful not to be “infected” with the sap. Mowing can be of some value, though that may well spread seeds and provide better sprouting conditions. Letting it go also seems to be somewhat effective in that it may be self limiting. There is, of course chemical means also (herbicides).
Treatment: The burning sensation can be relieved by covering affected areas with a cool, wet cloth. Try to delay blisters from rupturing as long as possible as blisters protect the skin by keeping it moist and clean while the areas heal. For those cases with extensive blistering, consult a doctor.
Tips to avoid exposure: wear gloves, long pants, and long-sleeved shirts. Planning control activities for the early evening will minimize sunlight and thus activation of the blistering process. If you are exposed to the plant juice, wash the contaminated areas thoroughly as soon as possible, using a stronger soap such as castille or dish soap.