Mark Renz opened with a timely overview of wild parsnip (Pastinaca sativa), which is currently flowering across much of Wisconsin. He emphasized its classification as a biennial to short-lived monocarpic perennial, meaning it typically flowers in its second year, sets seed, and dies. However, if the rosette doesn’t reach sufficient size, it may persist for additional years before flowering.

Wild parsnip thrives in sunny, open habitats—roadsides, grasslands, riparian zones, and disturbed prairies. Southern Wisconsin is a hotspot but it can be found throughout the state with over 23,000 documented observations. Seed dispersal is aided by flooding in riparian systems, making these areas key sources of reinfestation.

Mark highlighted a new invasive plant ID resource on his Renz Weed Science website that includes slides for over 100 regulated and common invasive plants, including wild parsnip.

The plant’s notoriety stems from its phytophotodermatitis—a chemical burn caused when sap contacts skin and is exposed to light. Unlike poison ivy, this is a chemical reaction, not an allergic one, and everyone is susceptible. Protective clothing and immediate washing are essential. Eye protection is especially important during hand-pulling or mowing.

Wild parsnip control strategies include:

• Hand removal: Effective for small populations using a sharp shovel (e.g., “parsnip predator”) to sever the root below the crown or hand pulling.
• Mowing: Must be timed when secondary flower heads are visible and petals have emerged but before seed set—typically late June in southern Wisconsin. Mowing too early allows regrowth and viable seed production.
• Grazing: Livestock, especially cattle, readily consume wild parsnip with minimal to no adverse effects.
• Herbicides: Spring applications (early May in southern WI, late May in the north) are most effective but applications are effective year-round. Products containing triclopyr, glyphosate, or 2,4-D are effective and available to the public.

He also addressed seed longevity (2–4 years) and the importance of landscape-scale management—controlling only roadside populations without addressing adjacent infestations leads to reinvasion.