Perennial pepperweed

• Perennial herb that grows up to 2 m tall
• Multiple waxy stems are greenish-grey, have a woody base, and may have red spots
• Leaves are smooth, lance-shaped, alternate, grey-green, have white mid-veins, and become reduced in size up the plant
• Rosettes are oval-oblong in shape with smooth or jagged edges
• Flowers are white clusters of four petals
• Fruits are small, round-oval pods, each containing two seeds
• Prefers salty soils, but grows in many habitats and soil conditions
  (e.g., agricultural areas, rangelands, roadsides, and riparian areas)

Perennial pepperweed patch.

Young leaves of perennial pepperweed.

Leaves are alternate, have a prominent white mid-vein, and become smaller up the stem.

Perennial pepperweed flowering.

Fruits of perennial pepperweed.

 

• Native to southeastern Europe and southwestern Asia
• Likely introduced to North America in the 1930s mixed into a shipment of sugar beet seeds
• In BC, it is known to occur in the East Kootenay, Thompson-Nicola, Cariboo, and Vancouver regions
• Reproduces by seeds, root fragments, and rhizomes
• Roots can be dormant for several years
• Spreads mainly by rhizomes, water currents, animal fur, contaminated seed mixes/forage/soil/straw, vehicles and equipment, and horticulture

• Forms dense monocultures quickly, reducing native plant diversity
• Increases soil salinity, inhibiting the growth of many other plants
• Threatens riparian areas, rangelands, croplands, pastures, and sensitive habitats such as marshlands
• Reduces crop yields and pasture productivity
• Reduces forage quality for livestock
• May make livestock ill when ingested
• Reduces nesting habitat when semi-woody stems accumulate

• Perennial pepperweed is classified as Prevent on the CKISS Annual Priority List.

• Perennial pepperweed is also classified as Provincial EDRR by the provincial government, and is managed by the Province. Please report any sightings immediately to the Province.
• It is currently not known to occur in the CKISS region.
• To learn more about how CKISS classifies and manages invasive species, see our Invasive Species Priority Lists page.

Prevention

• Do not plant this species. Learn about Grow Me Instead for native plant alternatives, and become PlantWise.
• Minimize soil disturbance and promptly revegetate bare, disturbed soils.
• Use hay and seed mixtures that are certified weed-free.
• Do not move contaminated soils to a new area.
• Clean clothing, boots, gear, machinery, and vehicles from soils and plant materials before entering/leaving an area.

Mechanical control

• Hand-pull or dig small infestations, removing as much of the roots as possible.
• Mow at flower bud stage to prevent seed set.
• Properly dispose of all plant parts in a bag for burial at a landfill.
• These methods will require repeated treatments to prevent seed spread.

Chemical control

• Has shown effectiveness when applied at the flowering stage and with other control methods (e.g., mowing).
• Foliar applications have shown to be effective.
• Post-emergent herbicides have been effective with repeat applications over several years.

Cultural control

• Grazing by sheep and goats in the growing season may suppress plant growth, but should be combined with other control methods.

Biological control

• There are currently no known biocontrol agents for this species in BC.

• Perennial pepperweed | Invasive Species Council of BC
• Perennial pepperweed | Provincial Invasive Species Alert
• Perennial pepperweed | SSISC
• Perennial pepperweed | King County