Johnson County Secondary Roads Wild Parsnip Weed

Wild Parsnip (Pastinaca sativa)

Description: Wild parsnip is a biennial with alternate, dark green leaves, and a deep, fleshy taproot. The first year wild parsnip grows as a rosette for at least one year, then sends up an erect, hollow, grooved stem. The flat-topped flower head is yellow to yellowish-red from which flattened, circular, brown seeds are produced. Wild parsnip can be identified from wild carrot and other parsley’s by its yellow flowers, square-like stem, and its pinnately compound leaves that are divided once into more than five leaflets. Wild Parsnip grows from 1-6 feet tall.

Distribution: Wild parsnip is found extensively in Johnson County. It can be found in moist, rich, alkaline soils in roadsides, ditches, pastures, and waste places.

What’s The Problem?: Leaves of wild parsnip contain the substance "psoralen", which may be transferred to the skin via contact with the sap or foliage, and increase the skin’s sensitivity to ultraviolet light. Many people are sensitive to the touch of the leaves and can develop a rash if their skin comes into contact with the leaves or sap while the sun is shining. A poison ivy-like rash can occur, with severe blistering and peeling. Some people say the rash and blistering is similar to a 2nd degree sunburn. This rash may take 2-3 weeks to fade. Wild parsnip also produces very abundant seed and can spread rapidly into new areas to compete with more beneficial native plants.

Management Methods: When attempting management of this weed, care should be taken to protect skin from the irritating sap. Wear gloves, long sleeves, pants, and boots. Good control can be achieved through hand pulling of small infestations before seeds develop. Hand cutting of the plant below the root crown can also be effective. Mowing is another good tool if done before seed sets. Mowing, however, may reduce competitiveness of other plants in the area. Use of herbicides can be a viable alternative in large infestations. Be certain to correctly identify plants and use the proper chemicals at labeled rates. Be sure to read and fully understand chemical labels before usage. Prescribed burning will not control wild parsnip, as it removes litter and increases amounts of sunlight to young plants. However, regular burning may increase the vigor and competitiveness of local plants, possibly decreasing wild parsnip populations. Establishment or maintenance of a competitive ground cover can be an excellent tool to control or prevent wild parsnip infestations.

Photo couresy of Weeds of Nebraska and the Great Plains published by Nebraska Department of Agriculture

photo of Wild Parsnip

Photo courtesy of K.R. Robertson, Illinois Natural History Survey

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