RMD-13-04: Consolidated Pest Risk Management Document for pest plants regulated by Canada
Appendix 5A: Pest Risk Assessment Summary for Crupina vulgaris (common crupina)

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Identity of Organism

Name: Crupina vulgaris Cass. (Asterales: Asteraceae)

Synonyms: Centaurea crupina L., Serratula crupina

English common names: Common crupina, crupina, bearded-creeper, starry scabious (Darbyshire, 2003; CABI, 2006)

French common names: Crupine, crupine vulgaire (Darbyshire 2003)

Description: Crupina vulgaris Cass. (Asterales: Asteraceae) is a facultative winter annual weed that is native to the Mediterranean region and has been recently (1968) introduced in the United States in Washington, Idaho, Oregon, California and Massachusetts. It is a serious weed of pastures, grasslands, rangelands, hayfields, and undisturbed roadsides and waste places.

Crupina vulgaris grows a slender taproot from one to several metres deep. The main flowering stem can range in height from 0.3-1.2 m. The top of the main flowering stem branches into 1-15 branches. In addition to short flowering branches at the top of the main flowering stem, additional flowering branches are produced in upper leaf axils.

Three to 130 capitula (flower heads) are produced per plant. Each capitulum bears 3-8 sterile flowers and 1-8 fertile flowers, with a normal combination of three sterile and two fertile flowers. Rose or purple petals partially protrude from the scaly floral bracts of the capitulum.

Seeds are cypselae with a dense pappus of blackish-brown bristles at the apex. Cypselae are a type of achene, a one-celled, one-seeded dry, hard fruits that do not open when ripe. The shape of the achene is roughly cylindrical, tapering at the base, and measuring 3-5 X 1.5-3 mm. The surface of the achene is black or silvery beige and covered with fine hairs.

Organism Status

Current native distribution of Crupina vulgaris is centred around the Mediterranean, ranging from southern Europe (Iberian Peninsula, France, Italy, Greece), across Turkey, and extending as far east as Xinjiang Province of China in Asia. In Africa, it is also considered native to Morocco, Libya and Algeria.

Crupina vulgaris is not present in Canada, but is invasive in several U.S. states (California, Oregon, Washington, and Idaho (USDA, NRCS 2009)).

The first successful introduction of Crupina vulgaris in the U.S. was discovered in Idaho in 1968. Later discoveries were from Sonoma County, California, in 1976 (declared eradicated in 1982), Chelan County, Washington, in 1983, Umatilla County, Oregon, in 1987, Sonoma County, California, in 1989 (a re-discovery), Modoc County, California, in 1990, and Wallowa County, Oregon and locations in Nez Perce County and the Snake River Canyon, Idaho, in 1995. It is estimated that Crupina vulgaris has invaded over 26,000 ha in Idaho, Oregon, California and Washington. The major populations of Crupina vulgaris remain widely separated and discrete, despite local expansion and dispersal to new satellites.

Two reports of Crupina vulgaris in Canada appear to be erroneous. Zamora et al. (1989) state that common crupina was found in British Columbia (no further details given). Garnatje et al. (2002) indicate, however, that this report appears to be in error, based on a personal communication reference with R. Cranston (a weed specialist previously with the B.C. Ministry of Agriculture and Food). Secondly, Thill et al. (1999) state that an infestation of common crupina was found near Pincher Creek, British Columbia, Canada, and eradicated between 1980 and 1986 (Pincher Creek is actually located in the province of Alberta). The personal communication reference for this statement, however, has indicated that he has no knowledge of an occurrence of common crupina in Canada (R. Cranston, previously of B.C. Ministry of Agriculture and Food, pers. comm. with K. Castro, Apr. 4, 2006). Furthermore, there are no records for common crupina in the municipal district of Pincher Creek (K. Cooley, Agricultural Fieldman, M.D. of Pincher Creek, pers. comm. with K. Castro, Apr. 4, 2006). Without further evidence to the contrary, common crupina is considered absent from Canada.

Current Regulatory Status

Crupina vulgaris is not currently regulated under the Plant Protection Act. Under the Seeds Act, Weed Seeds Order, 2005, it is listed as a Class 1 Prohibited Noxious Weed. All seed sold or offered for sale in Canada, as well as imported into Canada for the purpose of planting must be free of prohibited noxious weed seeds as set out in the Weed Seeds Order. At the provincial level, Crupina vulgaris is regulated in British Columbia.

In the United States, Crupina vulgaris is on the USDA's Regulated Pest List (USDA, APHIS 2009) and the Federal Noxious Weed List. It is also considered a noxious weed or plant pest in 15 states: Alabama, California, Colorado, Florida, Idaho, Massachusetts, Minnesota, Montana, Nevada, North Carolina, Oregon, South Carolina, South Dakota, Vermont and Washington (USDA, NRCS 2009).

Probability of Entry

Table 1: Summary of Pathways for Crupina vulgaris (common curpina)
Type of pathway Specific pathways
Natural dispersalCrupina vulgaris achenes can be dispersed by one or more natural means. (Achenes are small, one-seeded dry fruits. In the case of Crupina vulgaris, they resemble a seed.) Wind dispersal of the large, heavy achenes is limited to approximately 2 m or less. Achenes may be transported up to 15 m by rodents, which collect them in food caches, and 100 m or more by cattle and deer, on hooves and hair. Seeds have also survived passage through the digestive tracts of most animals except sheep. Water is a potential dispersal mechanism, although riparian zones are not a major habitat of Crupina vulgaris.
Intentional introductionAchenes may be transported by recreationists or tourists as a curiosity because they are similar in appearance to a fly fishing lure.
Unintentional introductionCanada imports live sheep, sheep wool, live cattle, hay and other forage products from the four states in which Crupina vulgaris is present. These imports represent potential unintentional pathways for this species into Canada. Crupina vulgaris could also be accidentally introduced in association with contaminated fabric, screens, farm machinery, trucks, rail cars, ballast soil, and/or sheep dogs moving across the border from the United States into Canada. Recreationists or tourists may unintentionally transport seeds of Crupina vulgaris on clothing and equipment.

Probability of Establishment

If introduced, Crupina vulgaris would most likely become established in parts of Canada. Based on current distribution, Crupina vulgaris could establish in five plant hardiness zones in Canada (zones 4-8) (Figure 1). This species may be able to establish in harsher climatic zones, an area of uncertainty that could be addressed through scientific research.

Figure 1: USDA Plant Hardiness Zones 4-11

Figure 1. Description follows.
Description of Figure 1:

This image is a map of Nord America showing the hardiness zones from 1 to 11 in different colors.

Probability of Spread

Crupina vulgaris reproduces by seed only. Relative to many other weedy species, Crupina vulgaris has a low seed output. Seed output ranges from 3-27 per plant in dry grasslands to as many as 850 per plant under favourable conditions (Roché 1996, cited in Roché and Thill 2001). Despite relatively low seed output, the large, heavy seeds have a relatively high success rate (Roché and Thill 2001). Dispersal potential is also greatly amplified by human-mediated dispersal pathways (Ising 1937; Sorrie and Sommers 1999). In the United States, Crupina vulgaris has proven to be invasive, and is a serious weed of grasslands, hayfields, pastures and rangelands (CABI 2006). The ability of Crupina vulgaris to establish in dry, sparsely vegetated areas and to compete with more desirable species are additional factors favouring the spread of this species.

Potential Economic Consequences

There is a high potential for serious economic consequences if Crupina vulgaris were to be introduced into Canada. Depending on the level of infestation and the potential range of the species, Crupina vulgaris could have serious negative economic impacts on at least two major industries in Canada: forage and livestock production (AAFC 2007). The marketing of seed commodities could also be affected, although it is considered unlikely that Crupina vulgaris would be found in cleaned seed lots.

Potential Environmental and Social Consequences

Crupina vulgaris contributes to the degradation of native and managed plant communities. It can be highly competitive and dominate sites, displacing other plant species and reducing biodiversity in the ecosystem. It also increases the risk of soil erosion (CABI 2006). Crupina vulgaris is not considered to have sociological impacts on aesthetics, recreation or property values (CABI 2005).

Uncertainty

There are three main areas of uncertainty for this risk assessment. One is the climatic amplitude for Crupina vulgaris. Further refinement of the range of temperatures over which Crupina vulgaris can survive would allow a more precise definition of the potential range of Crupina vulgaris in Canada. Its preference for warmer, more Mediterranean-type climates may limit its potential for invasiveness in Canada. Similarly, rainfall regime tolerances should be clarified, i.e., whether or not high rainfall (greater than 950 mm) is a limiting factor for Crupina vulgaris. Secondly, there is little information on economic impacts of Crupina vulgaris elsewhere where introduced. While it is known to impact livestock and forage production, the monetary value of potential economic impacts of Crupina vulgaris in Canada would be difficult to determine. Lastly, if introduced, Crupina vulgaris could potentially have negative impacts on species at risk in Canada, but it is unknown at this time if, how, or to what degree these impacts might manifest themselves.

Conclusion

It is considered likely that, without specific measures, Crupina vulgaris will be introduced into Canada via one or more of several pathways that have been identified for this species. British Columbia appears to be at the greatest risk, due to the combined factors of imported sheep, cattle and hay from states in which Crupina vulgaris occurs, as well as the availability of suitable habitats. However, it is possible that pathways for Crupina vulgaris could lead to its introduction in other parts of Canada as well.

If Crupina vulgaris became established in Canada, it would have negative economic impacts, especially to the hay and livestock industries. However, its limited natural dispersal ability and relatively low seed production suggest that, if detected early, eradication could be successful.

It is recommended that Crupina vulgaris be added to the List of Regulated Pests by Canadato prevent what would otherwise be a likely introduction of a damaging invasive plant species. This species should be regulated because 1) it is not yet present in Canada, 2) if detected early, there is a relatively good chance of eradication, 3) its potential economic impact is high, 4) no economic benefits of this species have been identified, and 5) it is known to have negative impacts on biodiversity in the areas it invades. Regulation of this species under the Plant Protection Act would also complement its regulation as a prohibited noxious weed under the Seeds Act.

Technical Issues for Consideration

More scientific research is needed to determine if this species is able to establish in harsher climatic zones and if it will have deleterious effects on endangered species and species at risk.

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