Weed Control
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Poison Hemlock
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Lepidium latifolium
Long-lived perennial
Identification and management tips
- A 1 - 3 foot tall perennial with waxy leaves, white flowers, and creeping rhizomes. Also known as tall whitetop.
- Perennial pepperweed is often confused with hoary cress (Cardaria draba); also called whitetop. However, unlike the taller perennial pepperweed, hoary cress stems are less than 3 feet tall and have leaves that clasp the stem and lack an obvious petiole.
- Impacts riparian areas and wetlands by forming large dense stands that displace native plants.
- For small infestations, pull or dig plants (try to remove as much of the root as possible) before they go to seed. This is an effective way of controlling a few scattered plants.
- For larger infestations, the use of glyphosate (Roundup and other products) in the spring is another option, but care must be taken to avoid injuring nearby plants.
- Again, timing is everything! Don't waste your glyphosate on mature pepperweed in July ....... it is just too late!
Most effective control methods and timing
| March | April | May | June | July | Aug | Sept | Oct |
|---|---|---|---|---|---|---|---|
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Prev Mech Chem |
Prev Mech Chem |
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Prevention (Prev)
Monitor and destroy new plants before seed production.
Mechanical (Mech)
Hand pulling, digging, cutting, mowing and tilling.
Cultural (Cult)
Biological control agents, livestock grazing, and revegetation practices.
Chemical (Chem)
Selective herbicides based on the plant and the specific location. Check our weed fact sheets for specific control information.
Links
- Weber County Weed Abatement: Controlling Whitetop & Perennial Pepperweed
- University of California: UC IPM; Perennial Pepperweed