Wild parsnip: problem plant in hay and pastures

Identifying

• Hairy, grooved and 2- to 5-foot tall stem

• Coarse, saw-toothed edged leaves

• Yellow umbrella-shaped flowers

• Looks similar to the ornamental Queen Anne’s Lace

• Biennial, completes its life cycle over two years

• Reproduces by seed

Where is it found? 

Wild parsnip grows throughout the United States and is found in fields, roadsides and sometimes wet pastures.

Toxicity 

Wild parsnip may have chemicals called furanocoumarins. These chemicals can cause severe sunburn (photosensitivity) in people and animals that eat them and become exposed to UV light (sunlight). Sunburn occurs after ingestion when furanocoumarins are in the blood vessels just below the skin.

Severe sunburn occurs on the white or other light-skinned areas, but not dark skinned areas. This is because the pigment, melanin, in the dark skin absorbs the UV light and prevents it from reacting with the furanocoumarins. Thus, shade from sunlight reduces severe sunburn in livestock eating plants with furanocoumarins.

Wild parsnip is toxic through all plant growth stages, when eaten fresh or dried in hay. Seeds also have high amounts of furanocoumarins.

Treatment 

Remove the plant source. Move animals to shaded areas. You can use topical treatments for skin wounds.

Control 

A few herbicides exist that help control wild parsnip. But you may need to re-apply them for control. Herbicides and mowing works better on smaller plants before their stems become woody. Always follow herbicide directions and grazing restrictions stated on the herbicide label.

You may need to remove larger plants by hand. Always wear gloves and protective clothing when coming in contact with wild parsnip to avoid severe blistering.

Authors: Krishona Martinson, Extension equine specialist, Lynn Hovda, DVM, adjunct assistant professor and Mike Murphy, DVM, former professor, College of Veterinary Medicine