Kangaroo Island
FacebookYouTubeInstagramSubscribe
Yellow burrweed (Amsinckia spp.)

Yellow burrweed (Amsinckia spp.)

Yellow burrweed is an Alert Weed for Kangaroo Island. Notify the Kangaroo Island Landscape Board. Early detection and control are the best way to prevent the next widespread weed. 

It is a declared plant for South Australia. 

THE SITUATION AND WHAT TO DO

Yellow burrweed is a winter-growing annual herb native to North and South America that can persist into summer. It was introduced to Australia accidentally through contaminated crop seed, fodder and machinery during early agricultural development. The plant is now naturalised across southern Australia and occurs as a weed in cropping areas, pastures, roadsides and disturbed land in many parts of South Australia.

Yellow burrweed is a declared pest plant in South Australia under the Landscape South Australia Act 2019 

Yellow burrweed spreads only by seed. Seeds are easily transported in contaminated grain, hay or fodder, on machinery, and by attaching to wool, fur or clothing. They may also pass through livestock or birds and be spread during road maintenance or soil movement.

On Kangaroo Island, yellow burrweed is currently known to occur within the Hundred of Haines where it has been controlled for several years. There have also been several other reports of yellow burweed on Kangaroo Island from contaminated hay and grain.

To prevent Yellow burweed in becoming established on Kangaroo Island:

  • Report any new infestations to the Kangaroo Island Landscape Board.
  • Landholders should control yellow burweed on their property.
  • Practice good hygiene when moving machinery.
  • Do not sell hay or fodder from pasture where yellow burrweed is present, and
  • Requesting a vendor declaration when purchasing farm produce or stock feed.
Yellow burrweed (Amsinckia spp.)

DESCRIPTION

  • Growth form: erect, bristly annual herb usually 20–70 cm tall. Plants develop a basal rosette during winter and produce upright flowering stems in late winter and spring.
  • Leaves: narrow, rough and hairy leaves. Lower leaves form a rosette at ground level, while smaller alternate leaves occur along the stems.
  • Flowers: small bright yellow, trumpet-shaped flowers (about 5–10 mm long) arranged along one side of a curved, coiled spike that gradually unrolls as it grows.
  • Fruit: a bristly cluster that breaks into four rough, hard nutlets when mature.
  • Seed: ach flower produces four seeds. Plants can produce up to about 1,600 seeds per plant, forming a persistent seedbank. Most seed remain viable for up to about 2 years, although some may survive for as long as five years in the soil.

IMPACTS

Yellow burrweed is a competitive weed of cereals and pastures, capable of reducing crop yields and pasture productivity by competing for nutrients, light and moisture. Seeds and plant fragments can contaminate grain and wool, lowering product quality. The plant is also toxic to livestock, causing liver damage when eaten in significant quantities. Dense infestations can therefore impact both cropping and grazing enterprises.

CONTROL OPTIONS

Effective management relies on preventing seed production and reducing the soil seedbank. Small infestations can be controlled by hand pulling or cultivation before flowering. Selective herbicides can be used in crops and pastures when plants are young. Maintaining competitive pastures or crops helps suppress establishment, as the weed thrives in bare or disturbed ground. 

Hygiene measures—such as cleaning machinery and avoiding contaminated fodder—are important to prevent spread. As yellow burrweed reproduces only by seed, consistent control over several seasons can significantly reduce infestations.

Permitted and on-label herbicides and rates can be found on the PIRSA Weed Control Website.

DECLARATIONS

Yellow burrweed is declared under the following sections of the Landscape South Australia Act 2019 :

  • 186(2) Prohibiting movement on public roads
  • 188(1) Prohibiting sale of the plant
  • 188(2) Prohibiting sale of contaminated goods
  • 192(2) Landowners to control the plant on their properties
  • 194 Recovery of control costs on adjoining road reserves

FURTHER INFORMATION

Download PDF