COUNTY AG NEWS
Spray Wild Parsnip now
Wild parsnip is among the rapidly increasing invasive weeds in many areas of Wisconsin. Wild parsnip is a yellow-green, tall plant that grows to around five feet tall. Wild parsnip is of concern because humans develop a severe skin irritation from contact with its leaves. Plants have chemicals called furocoumarins that cause an interaction between plants and light that induces skin inflammation.
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. Parsnip burns usually occur in streaks and elongated spots, reflecting where a damaged leaf or stem moved across the skin before exposure to sunlight.
You can brush against wild parsnip plants and not be affected. Wild parsnip is only dangerous when the plant sap from broken leaves or stems gets on your skin.
One of the worst things to do is to use a weed eater to remove wild parsnip. This type of mechanical removal will splatter the plant sap all over the person and cause widespread burns and blisters. In cases of mild exposure to wild parsnip, affected areas turn red and feel sunburned.
In severe cases, the skin first turns red and then blisters form. The arms, legs, torso, face, and neck are most vulnerable and affected areas may feel like they have been scalded. Blisters form a day or two after sun exposure and soon after the blisters rupture and the skin starts healing. But for many people the ordeal is not over as dark red or brownish scars remain in the burned areas for several months to years.
Wild parsnip germinates in the fall and forms a rosette or a small clump of leaves at the soil surface. In the spring, the plant will produce a plant, which may reach up to five-feet tall. The plants are yellow-green and produce umbel shaped flower heads that are four to eight inches in diameter. The individual flowers are yellow with five petals.
Plants can be controlled mechanically by cutting them just below the soil surface. Mowing will not kill wild parsnip plants but will reduce seed production. A timely application of 2,4-D and/or dicamba to plants in the rosette growth stage (early fall or late April to mid-May) should control all treated plants. Careful applications of glyphosate will also kill wild parsnip plants.
By the time plants are bolting or flowering, mowing is the best alternative. The delay in mowing roadsides until mid summer opens the door for this plant to complete its life cycle and produce ripe seeds well before any mowing is done. When roadsides and pastures are mowed in late July and August, wild parsnip seeds move as hitchhikers on the mowers. Mowing also creates a much more favorable environment for parsnip seeds to germinate than if the sites were left undisturbed.
Relatively mild winters may enhance survival of wild parsnip plants that germinate and become established in the fall. Being able to readily identify wild parsnip and early detection of infested areas will minimize inadvertent and excessive exposure to this plant and the often painful results that follow.
Additional information on wild parsnip including pictures of wild parsnip and of the burns and blisters caused by wild parsnip may be found on the publication on the following website: http://waushara.uwex.edu/agriculture/wild-parsnip/.