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Report an Invasive Species

Field scabious

Field scabious

Field scabious

(Knautia arvensis)

Priority: -  Prevent

Tags: Terrestrial

Identification and Reproduction

Identification: 

  • Field scabious is a tall perennial that grows from a deep taproot. 
  • Stems are erect, hairy and sparsely branched. This plant grows up to 1.5 m tall. 
  • Leaves are also hairy and the extent of the lobes are dependent on their life stage. As a rosette leaves are lance-shaped and pointed to a tip. After bolting, stem leaves are arranged oppositely, pinnately lobed and attached directly to the stem. Leaf size will decrease moving up the stem. 

  • This plant produces composite flowers that are small (4 cm) and violet-blue to purple. Bracts are narrow and bright green. Flowering occurs between July and September. 
  • After flowering the seedheads develop, becoming domed and covered in short hairs. 

Reproduction: 

  • A single plant can produce up to 2,000 seeds per growing season. 

Habitat & Ecology

  • It thrives in nutrient-rick and moderately dry soils but has also been known to establish in gravelly soils. 
  • It prefers grassy areas with dy soils. 
  • Currently present in BC in the specific regions: Bulkley-Nechako, Kootenay-Boundary, and Thompson-Nicola regions. 

Impacts

Social:

  • This plant out-competes foraging and pasture plants. 
  • Causes decline in hay production and pasture carrying potential. 
  • Once established it is difficult to eradicate. 

Management

Prevention is a high priority for this plant. 

  • Please report this plant if you think you have seen it. 

Mechanical/Manual Control: 

  • Small, young infestations can easily be pulled by hand. 
  • Repeated mowing can also help deplete the taproot resources. 
  • Prior to flowering cultivation can be efficient. 
  • Be sure to wear gloves, long sleeves and pants to prevent contact with plant hairs. 

Chemical Control: 

  • Currently picloram and metsulfuron-methyl are registered for use on field scabious. 
  • Please carefully read all labels prior to application. 

Resources

Download the Alberta Invasive Species Council's factsheet for field scabious here

Download A Guide to Weeds in British Columbia: Field Scabious here

Header photo (Udo Schmidt).