RMD-13-04: Consolidated Pest Risk Management Document for pest plants regulated by Canada
Appendix 12B: Risk Management Considerations for Senecio inaequidens (South African ragwort)
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Values at Risk
- Canadian Livestock Industry:
- Senecio inaequidens contains 4 different pyrrolizidine alkaloids, two of which are known hepatotoxins (Dimande et al. 2007). These chemicals are poisonous to grazing animals, including cattle and sheep, which have resulted in death (Scherber 2007, Dimande et al. 2007). The total export value of cattle, sheep and horse products originating from the Canadian provinces where Senecio inaequidens is likely to invade was approximately $450 million in 2008 (Industry Canada 2009). In addition to directly affecting livestock, pastureland yields could decrease if the weed is introduced into Canada.
- Canadian Wine Industry:
- This species has the potential to colonize vineyards affecting the Lake Erie North Shore and Pelee Island wine regions of Ontario. In 2007, approximately $5 million worth of grapes Footnote 1 were produced in the counties of Ontario where this species could become established (OMAFRA 2009). The coastal wine-growing region of B.C. could also be affected by Senecio inaequidens affecting $1.6 million.
- Biological Diversity:
- There is evidence that Senecio inaequidens threatens biological diversity.
- Animal Health:
- The plant contains pyrrolizidine alkaloids which are toxic to livestock and humans and may affect consumer demand for milk and honey.
Pathways of Introduction
The major pathways for the natural dispersal of Senecio inaequidens are wind, animals, and water. The risk of introduction into Canada from these natural dispersion mechanisms is low as there are no populations present near Canadian borders.
There are no identified intentional introduction pathways for the entry.
- Field crops not intended for propagation. The level of risk associated with the import of cereal grain into Canada is very low since imports originate primarily from areas where Senecio inaequidens is absent.
- Hay and Straw. The level of risk associated with imports of hay and straw into Canada is relatively low since they originate primarily from areas where Senecio inaequidens is absent.
- Livestock. The level of risk associated with the importation of livestock is low because of the small number of animals imported into Canada from countries where Senecio inaequidens is present.
- Vehicles and Used Farm Machinery. Information is not available on the volume of imports of used farm machinery. The lik lihood of Senecio inaequidens being introdued into Canada from seeds adhering to tires is low.
- Nursery Stock with Soil. Not present in United-States so it is not likely to be introduced to Canada through nursery stock with soil.
- Travelers and Their Effects. Travelers are not likely to bring Senecio inaequidens back into Canada unintentionally.
- Packaging Material. Container surfaces are a potential pathway of introduction for Senecio inaequidens. The achenes are more likely to attach to rough surfaces (e.g.. wood) rather than smooth ones, due to the nature of the seed. This pathway is considered low risk.
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