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Southern Interior Weed Management Committee

2 copiaThe new 2016 - 2017 Plant Priority Ranking has been released! The following information will be used to plan our field season;


Plant Priority →    1 1 2 3  
Scientific Name Common Name SIWMC Watch list Regional EDRR High Priority Medium Priority Low Priority Bio-control
Abutilon theophrasti Velvetleaf X          
Acroptilon repens Russian knapweed         X  
Aegilops cylindrica Jointed goatgrass X PR          
Alliaria petiolata Garlic mustard X          
Anchusa officinalis Common bugloss X          
Anthriscus sylvestris Wild chervil X          
Arctium spp Burdock spp.         X  
Berteroa incana Hoary alyssum       X    
Cardaria draba Hoary cress         X  
Carduus acanthoides Plumeless thistle         X  
Carduus nutans Nodding thistle         X  
Cenchrus longispinus Longspine sandbur X          
Centaurea stoebe Spotted knapweed       X    
Centaurea diffusa Diffuse knapweed         X X
Centaurea solstitialis Yellow starthistle X PR          
Centaurea spp. Knapweed species (brown, black, meadow, bighead) X          
Centauria cyanus Bachelor's buttons       X    
Chondrilla juncea Rush skeletonweed X X PR        
Cirsium arvense Canada thistle         X  
Cirsium palustre Marsh plume thistle   X        
Crupina vulgaris Common crupina X          
Cynoglossum officinale Hound’s-tongue         X X
Cytisus scoparius Scotch broom X          
Dipsacus fullonum Teasel     X      
Echium vulgare Blueweed     X      
Elaeagnus angustifolia Russian olive         X  
Eremopyrum triticeum Annual wheatgrass X          
Euphorbia esula Leafy spurge       X    
Fallopia and Polygonum Knotweed species (Bohemian and Japanese)     X      
Gypsophila paniculata Baby’s breath         X  
Heracleum mantegazzianum Giant hogweed x          
Hieracium aurantiacum Orange hawkweed       X    
Hieracium flagellare Whiplash hawkweed X          
Hieracium spp Yellow hawkweed complex         X  
Hyoscyamus niger Black henbane   X PR        
Impatiens glandulifera Himalayan balsam         X  
Iris pseudacorous Yellow flag-iris     X      
Knautia arvensis Field scabious   X        
Lepidium latifolium Perennial pepperweed   X PR        
Leucanthumum vulgare Oxeye daisy         X  
Linaria dalmatica Dalmatian toadflax         X X
Linaria vulgaris Yellow toadflax         X  
Lythrum salicaria Purple loosestrife           X
Mirabilis nyctaginea Wild-4-O’clock X          
Onopordum acanthium Scotch thistle   X        
Polygonum polystachyum Himalayan knotweed X          
Potentilla recta Sulphur cinquefoil       X    
Rubus discolor Himalayan blackberry X          
Senecio jacobaea Tansy ragwort     X      
Silybum marianum Milk thistle X          
Tanacetum vulgare Common tansy     X      
Thymelaea passerine Spurge flax X          
Tribulus terrestris Puncturevine X          
Tripleurospermum inodorum Scentless Camomile         X  
Zygophyllum fabago Syrian bean-caper X          
  • PR indicates a Provincially listed Early Detection and Rapid Response (EDRR) species
SIWMC Watch List Not present in the Thompson-Nicola Regional District. Mgt. objective - early detection
Regional/Provincial EDRR Species Poses a significant threat and is new to the area, eg less than 10 small sites. Objective is eradication
High Priority Species High risk/impact; limited population with significant potential to spread in the region. Objective is to contain to prevent further expansion. If the population is low enough, the objective will be to control every site annually.
Medium Priority Species Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.  Objective is to control to prevent further expansion to protect unique habitats, agriculture, etc. – may mean establishing containment lines to identify sites outside the line for control.
Low Priority Species

Low risk; may be widespread or not, may be of concern in specific situations with certain high values – e.g. conservation lands, specific agriculture crops.

Biocontrol Invasive Plant Species is treated primarily with biocontrol agents or considered under successful biocontrol in the region.

Noxious weeds are non-native plant species that are difficult to control. In the absence of their natural predators and diseases, these weeds aggressively compete with native plants for water and nutrients, threatening the health of natural and economic resources and the industries that they support.

The Southern Interior Weed Management Committee (SIWMC) is a registered charity comprised of volunteer members representing private & public agencies, clubs and organizations in the Thompson-Nicola Region of British Columbia. Members of the society are dedicated to increasing awareness of invasive plants and associated losses caused to the natural and domestic resources of our region.

If you find an invasive weed here is the place to let someone know.. Report-A Weed ... or you can tell us through our contact us tab above.


 sulphur cinquefoil flower 1 oange hawkweed flower   spotted knapweed plant  blueweedflower1
 Sulphur Cinquefoil
Potentilla recta
 Orange Hawkweed
Hieracium aurantiacum
Spotted Knapweed
Centaurea biebersteinii 
Echium vulgare 



'Knapweed is highly competitive and capable of invading grassland sites to the exclusion of native vegetation. Domestic animals and wildlife, such as elk, rely on these range grasses and herbs for up to 80 percent of their diet. Knapweed encroachment can destroy the forage base and would result in a significant decline in deer and elk numbers. Over 40,000 hectares in BC are knapweed infested, reducing forage potential by up to 90 percent.'


Information taken from British Columbia Ministry of Agriculture and Lands
webpage: "Knapweed - Its Cost to British Columbia"

The goals of the SIWMC are to:

EDUCATE landowners and managers about invasive plant impacts on the natural diversity of the environment

PROMOTE integrated management for the prevention, eradication, control or containment of invasive plant species

ENCOURAGE expanded support for local invasive plant control programs and initiatives

ASSIST with management efforts of noxious and invasive weeds on public and private lands

INVENTORY invasive plants on private and public lands located within the Thompson-Nicola region

"Be wise about weeds"



To learn more, check out the new invaders page.


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