photoS: Alberta Sustainable Field Scabious Resource Development (Knautia arvensis) Provincial Designation: Noxious Overview: Identification: Field scabious is native to Europe and was Stems: Stems are erect, introduced as an ornamental plant. It is a hairy, sparsely branched, tall perennial that favors grassy areas and and grow up to 1.5 m tall. Seedhead develops a deep tap root. The flowers very There can be one or sev- closely resemble those of another orna- eral stems per plant, with mental perennial, Scabiosa (butterfly plant, little or no branching in the upper stem. times will require many years of diligent control pincushion flower) but each plant belongs to Leaves: Leaves are hairy and the degree of work to eradicate. Since this plant favors grassy a different genus. the lobes is highly variable. Young rosettes areas such as hayfields, it can be widely dis- leaves tend to be lance-shaped, have pointed persed in baled forage. Habitat: tips, and the margins can be entire or coarsely Prefers nutrient-rich and toothed – sometimes a few leaves will be pin- Control: moderately dry nately lobed. Stem leaves are opposite, pinnate Grazing: Field scabious is not palatable and soils, but can (deeply lobed) and attached directly to the seeds can be transported by animal movement. also establish stem. Lower leaves are 10-25 cm long but be- Invasive plants should never be considered as in gravelly come smaller higher on the plant. forage. soils. Flowers: Flowers are a composite of small, vi- Cultivation: Discing before flowering is effec- olet-blue to purple florets clustered into a head tive in crop land situations. resembling a single flower up to 4 cm wide, and occur singly at the ends of stems. Occasionally Mechanical: Mowing is effective to prevent flowering stems arise from leaf axils lower on seed production but would likely need to be the stem. Below the flower head is a ring of nar- repeated in the season because of re-sprouting. row green bracts. Flowers are hermaphroditic The deep tap root is difficult to remove in any- (having both male and female organs). thing but loose soils; therefore hand pulling usu- Seeds: Once flowering is complete the seed ally results in the stem breaking off at ground head is domed and covered with short, bristly level and then re-sprouting occurs. However, hairs. The fruit is nut like, cylindrical and hairy, any removal of seed is beneficial. Wear long 5-6mm in size. Seeds fall around the parent sleeves and gloves as skin contact with the plant. A single plant can produce up to 2000 hairy plant causes considerable itching. seeds that remain viable for many years. Chemical:1 Picloram, clopyralid, and metsul- furon methyl are effective, mainly on rosettes Prevention: and young bolts. Another application in the fall is ef- Field scabious can invade fective for killing re-sprout- undisturbed plant communi- ing from roots. Consult your ties, and once established is local Agricultural Fieldman very difficult to control, but or Certified Pesticide Dis- maintaining healthy cover penser for more informa- can help to prevent against tion. invasion. Any field scabious infestation that has been Biological: None re- allowed to go to seed a few Rosette searched to date. Bolting 1 Always follow the product labels. The use of pesticides in any manner not published on the label or registered under the Minor Use of Pesticides regulation constitutes an offence under both the Federal Pest Control Products Act and Alberta’s Environmental Protection and Enhancement Act. www.invasiveplants.ab.ca.