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African daisy (Senecio pterophorus)

African daisy is an aggressive weed of disturbed sites that can compete strongly with pasture and crops, reducing agricultural productivity. In natural areas it can form dense thickets that displace native plants and reduce habitat.

Key facts

Type: Weed, shrub.

Native to: South Africa.

Established in: NSW, VIC, SA.

Other names: Rough Senecio, Winged Groundsel.

Best time to act: Flowering occurs from November through autumn, so find plants and treat isolated ones before they flower; seeds usually germinate with the early April and May rains.

Identification

  • An erect, tufted perennial herb or shrub, usually 1–1.5 m high, with several stems.
  • Stems are greyish-green and ribbed, with distinctive wings along their lower parts; young stems may have a white cobweb-like covering.
  • Leaves are glossy green above and white or grey and cobweb-like below, with lower leaves usually having forward-pointing teeth.
  • Bright yellow, daisy-like flower heads grow in groups at the top of the plant, with about 40–200 heads per stem.
  • The small brown or reddish-brown ribbed fruits have a ring of slender white hairs.
  • Look-alike: It may be confused with varieties of Senecio linearifolius. African daisy usually has winged stems, toothed leaves that are glossy above and woolly below, and bell-shaped flower heads with 8–13 outer yellow florets; S. linearifolius has unwinged stems, often hairless leaves, and cylindric heads with 4–8 outer florets.

Where it grows

In Australia it occurs in South Australia, Victoria and New South Wales, particularly on roadsides, railway lines, cleared or denuded land, pastures and disturbed native vegetation.

Why it matters

  • It competes aggressively with developing pastures and crops and can dominate infested land, causing heavy productivity losses.
  • It contains the toxic alkaloids senecionine and seneciphylline, although it is rarely eaten by grazing livestock in Australia and no stock deaths have been reported here.
  • In natural areas it can form dense thickets that exclude native plants and reduce habitat.
  • It grows vigorously on burnt areas and can displace native plants.

How it spreads

  • Most seeds are dispersed by wind, water, animals and vehicles, although many fall close to the parent plant.
  • Some spread may occur in contaminated soil and agricultural produce.

Control options

  • Spot spray isolated plants before flowering using registered herbicides, following applicable product directions.
  • Hand-pull isolated plants and small infestations, removing roots to a depth of 200 mm; bag and dispose of flowering heads to prevent seed spread.
  • Cut larger plants close to ground level and paint the stem bases with herbicide, or repeatedly slash larger populations to limit flowering and seeding.
  • In pasture, cultivate where suitable and establish competitive pasture with a legume component; seedlings on suitable steep sites can be heavily grazed by sheep or goats, but avoid overgrazing that leaves bare ground.

Hygiene and washdown

  • Seeds can spread on vehicles and in contaminated soil or agricultural produce; check vehicles and machinery and avoid moving soil or produce from infested sites.
  • 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): No national listing. Managed under state and territory law.
  • 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: Regionally prohibited / regionally controlled / restricted weed (varies by region). Where it is regionally prohibited, landowners must take all reasonable steps to eradicate it on their land. Where it is regionally controlled, landowners must take all reasonable steps to prevent its growth and spread on their land. Where it is a restricted weed, trade in it (including the plant, its seed or contaminated material) is prohibited.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • 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.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources