Invasive Plants

Index

Noxious and Invasive Plants

Plants defined as noxious or invasive are usually alien species with no natural predators or diseases to keep them in check. Noxious and invasive plants can severely impact their surroundings by:

• Crowding out native plants.
  
• Damaging infrastructure over time.
  
• Degrading sport field turf.
  

• Physically harming humans and local wildlife.
  

Help remove invasive plantlife naturally by pulling and cutting (where appropriate) and only use herbicides when necessary and as a last resort. Do not plant invasive species in gardens or other greenspaces.

Current Infestations

KNOTWEED SPECIES

• Can grow through one metre of concrete and roots extend up to three metres in depth.
  
• Very difficult to manage without major excavation or repeated herbicide applications.
  
• A new colony can start from a 2.5cm fragment.
  
• Do not mow and do not compost
  
• Report infestations immediately.
  

BURDOCK

• Burrs attach easily to clothing, hair, pets, etc.
  
• Burrs can cause deadly sores that can kill wildfire.
  
• Do not pull out infestations.
  
• Cut plant above rosette when burrs have developed.
  

COMMON TANSY

• Can cause skin inflammation in some people.
• Cows that eat its leaves may produce tainted milk with an unpleasant taste.
  
• Easily spread by vehicles like road maintenance equipment.
  
• Dried remains are stiff and sharp.
  
• Dispose of by cutting off seed heads and pulling the plants by its individual stems.
  

LEAFY SPURGE

• Plant parts contain a milky white latex that can cause skin irritation.
  
• Plant latex can cause blindness if it gets in eyes.
  
• Report infestations immediately.
  
• Do not pull or dig.
  

Other Invasive Plants in Prince George

Blueweed

• Invades roadsides, drainage ditches, pastures, and other undisturbed sites.
  
• Produces up to 2,800 seeds per plant.
  
• Painful to touch (wear thick gloves to pull small infestations).
  

Chicory

• Commonly found on roadsides and campsites.
  
• Easily spread on all types of vehicles.
  
• Dig up and dispose in garbage.
  
• Do not compost.
  
• Report infestations immediately.
  

Himalayan Balsam

• Displaces native plants and alters wildlife habitats.
  
• Produces up to 2,500 seeds per plant annually.
  
• Shallow roots can cause soil erosion.
  
• Do not pull. Cut off before plant goes to seed.
  
• Do not purchase and plant.
  
• Do not compost.
  

Hoary Alyssum

• Toxic to horses. Consumption may cause fever, limb edema, and laminitis.
  
• Invades dry land, rangelands, and forage craps.
  
• Small infestations can be controlled by repeated hand-pulling or hoeing.
  
• Larger infestations can be mowed repeatedly each season at progressively lower mower heights.
  
• Report infestations immediately.
  

Knapweed SPECIES

• Easily spread by road maintenance equipment.
  
• Major concern to agriculture with 13 known species in B.C.
  
• Easily treated with herbicide before seeds set.
  
• Cut off seed heads. Pull plants by twisting out at base to remove taproot. Bag and dispose of in garbage.
  

Sedum Acre

• May cause respiratory distress when cut with string trimmers.
  
• Spreads rapidly on non-irrigated turf.
  
• Easily spread by all types of mowing equipment.
  
• Small fragments can start new infestations.
  
• Wash all equipment before leaving infested sites.
  
• Report infestations immediately.
  

Scentless Chamomile

• Spreads rapidly.
  
• Single plant can produce one million viable seeds as soon as flowers bloom.
  
• Do not pull or dig out from soil.
  
• Cut down infestations before flowers appear.
  
• Report infestations immediately.
  

St. John's Wort

• Contains toxin that causes grazing animals to become sensitive to sunlight and intense skin irritation.
  
• Major concern to agriculture.
  
• Dispose of by cutting off seed heads, pulling plants, bagging, and throwing away in garbage.
  
• Report infestations immediately.
  

Report an Infestation

• Visit Reportaweedbc.ca to learn how to report infestations online
  
• Phone the Northwest Invasive Plant Council weed hotline at 1-866-44WEEDS
  

Additional Resources

• Visit the Invasive Species Council of BC website for more information on invasive plant and animals
  
• Visit the Northern Invasive Plant Council website
  
• Learn how to be PlantWise to minimize invasive plant exposure
  

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