Wild parsnip is an herbaceous invasive species that can grow up to 5 feet. This species is typically found in open and sunny areas. This includes roadsides, fields, fens, and pastures. The leaves have 2 to 5 leaflets that are across from each other up the stem. The leaves are often toothed and shaped like a mitten. The small yellow flowers bloom between June and July and can reach 6 inches in width when clumped together. Two similar species are cow parsnip (Heracleum maculatum) and giant hogweed (Heracleum mentagazianum). Both of these species have yellow flower clusters and larger lobed leaves.
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Environmental and Human Effects
It is important to note that wild parsnips’ sap contains chemicals that can burn your skin if it comes into contact with sunlight. This is most common to happen when the plant is flowering, but all parts of the plant contain the chemical. Much like other invasive species, wild parsnip can form dense patches that hinders native plant’s ability to grow. Unfortunately, this plant is not very pollinator friendly.
Treatment
There are several treatment methods that can be effective for this species. This includes both non-chemical and chemical methods. Whichever method is used, it is important to wear protective gear including long sleeves, glasses, and gloves.
NON-CHEMICAL METHODS
- Hand pulling: this species has a deep tap root, so if the soil is moist or loose, hand pulling can be effective. If the entire root system is not removed the plant may resprout. It is best to use this method before the seeds have ripened, otherwise you run the risk of helping disperse the seeds when you remove the plant. If flowers are in bloom, bag them and dispose of them in a landfill. Note: you should plan to retreat this site for at least four years to remove the entire population.
- Mowing: this could be a good option if the population is not well established. Mowing the area repeatedly can suppress the seed production. You should plan to re-mow this area for 4 to 5 years in order to get rid of the plant completely. Note: you should mow the area before the seeds have enlarged, otherwise you will help with the dispersal.
- Clipping: if the population is small enough and not well established, you can clip the flowers off the plant once they emerge. You should bag up the flowers and dispose of them in a landfill to prevent spreading the species further. This helps stop seed production and can prevent more plants from emerging. Plan to do this for several years in a row.
CHEMICAL METHODS
- Foliar spraying: if the patch is dense enough, you may spray herbicide onto the foliage and kill the species that way. Note: follow all safety procedures on the herbicide label.