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Narrow-leaved ragwort (Senecio inaequidens)

It is recorded in Australia in Queensland, New South Wales and Victoria under the name Senecio madagascariensis. It can spread vigorously and is toxic to people and livestock.

Key facts

Type: Weed, herb.

Native to: South Africa, including the Lesotho region.

Established in: .

Other names: South African ragwort, séneçon du Cap, schmalblättriges Greiskraut, senecione sudafricano.

Best time to act: Treat before flowering and monitor for several years, removing new plants whenever they establish.

Identification

  • A perennial herb or woody shrub that can grow up to 1 m tall, with erect stems branching from a woody base.
  • Its bright-green leaves are alternate, narrow and variable in shape, usually 3 to 14 cm long, with toothed or irregularly notched edges.
  • It produces open clusters of yellow flowerheads, usually 18 to 25 mm across; flowering in France is reported from April to January.
  • The cylindrical, hairy achenes are 2 to 2.5 mm long and have a white pappus that is two to three times their length.
  • Look-alike: It may resemble Senecio lythroides, which is indigenous to the Western Mediterranean area.

Where it grows

It grows in open or disturbed places such as wasteland, fallows, roadsides, railway tracks, vineyards, burnt land and pastures, and also occurs in dunes, cliffs and temporary ponds.

Why it matters

  • It is reported as a weed in vineyards and reduces the value of invaded pastures.
  • Dense populations can interfere with management of ruderal areas, and invasion of natural habitats can threaten biodiversity, including the native Centaurea corymbosa in France.
  • It contains pyrrolizidine alkaloids and is toxic to people and livestock; it is poisonous to horses and may cause their death.
  • Its effects on honey composition are not well known, and the alkaloids are reported as a threat to milk production.

How it spreads

  • Large numbers of seeds are dispersed by wind over long distances; birds and mammals can also carry them.
  • Road and rail vehicles, soil, building materials and machinery are possible movement pathways.
  • Historically, it reached Europe as a contaminant of imported wool; containers, packing and trade or transport of plant products are also mentioned as possible pathways.

Control options

  • Hand-pull plants in small areas or mow before flowering; repeat control over several years and whenever new plants establish.
  • Collect and destroy pulled plants, as they can continue producing achenes for two or three days after removal.
  • In vineyards, low-toxicity phytosanitary products have been reported as effective; selective phytosanitary products have given good results on mature plants in pastures.
  • Reducing fire risk, avoiding overgrazing and sowing perennial species with good ground cover, such as Trifolium species, are measures reported to limit invasion.

Hygiene and washdown

  • Road and rail vehicles, soil, building materials and machinery are identified as possible movement pathways; seeds may also be carried by animals.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): National priority exotic pest. On the National Priority List of Exotic Environmental Pests, Weeds and Diseases, so any new detection should be reported straight away.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

Sources