Cape weed

Scientific name: Arctotheca calendula
  • Key characteristics
  • Biology
  • Impacts
  • Control
  • Further information

  • An annual species with a low growing, flattened rosette of leaves common in short turf areas like lawns and playing fields, roadsides and coastal waste areas
  • Leaves greyish-green, deeply cut into many lobes, with a larger terminal lobe
  • Underside of leaves much paler and covered in woolly hairs
  • Attractive solitary flower head 3-4 cm across, with yellow ray florets (‘petals’) and a dark purple centre
  • The pappus is very ‘woolly’ giving the seed head a strawberry-like appearance.

Other similar species present in New Zealand

  • Plants with similar flowers are species of gazania (Gazania linearis and Gazania rigens) and the African daisy Arctotis stoechadifolia. These are common garden escapes, often found along roadsides, where garden rubbish has been thrown out, or on sand dunes near coastal settlements.

Origin

  • Native to South Africa (hence the name ‘Cape weed’, with a capital C)
  • First recorded in New Zealand in 1869
  • Now common throughout the North Island, and in areas of Marlborough, Nelson and Canterbury
  • Found along roadsides, in waste places, on consolidated sands and in short turf such as lawns, playing fields, and pasture
  • Originally confined to coastal areas but now increasingly found inland.

Life cycle

  • Cape weed produces large amounts of seed and when it dies off in summer it leaves bare areas in which its own seedlings can establish
  • The woolly pappus readily sticks to socks, animals etc. but is not widely dispersed by wind
  • Plants are in flower between October and December
  • Rosettes are large and the plants compete strongly against other turf species. Capeweed can dominate large areas of depleted pasture
  • Adapted to most soil types but probably grows best on lighter soils and is most aggressive on fertile soils.

Benefits

  • May help prevent soil erosion.

Impact on pasture and livestock

  • Smothers and replaces more desirable and highly producing pasture species
  • Capeweed tends to self-perpetuate since its seeds germinate in the bare spaces left by the death of the parent plants
  • Difficult for cattle to graze
  • Foliage has poisoned cattle in New Zealand and cattle and sheep in Australia, probably due to high levels of nitrate.

Grazing management

  • Pastures should be kept dense in autumn to prevent Cape weed re-establishing each year. This can be done by selection of appropriate grass cultivars or by grazing management, especially rotational grazing.

Chemical control

  • Once present in lawns, best control is by using clopyralid, or herbicides containing dicamba or picloram
  • Note that all these herbicides leave residues in the turf after application so clippings should not be composted until several months afterwards
  • Note also that picloram is highly soluble and can leach to the root zone of adjacent trees with disastrous results
  • Young rosettes can be killed using MCPA or 2,4-D
  • Older plants can only be killed by clover-damaging herbicides.

Integrated control

  • Cape weed establishes best after turf has opened up during drought, so avoid this if possible, by using turf or pasture cultivars that tolerate dry conditions
  • In lawns where Cape weed is just starting to establish, care should be taken not to spread the seeds to new areas
  • A possible strategy to avoid seed dispersal is to leave mowing infested patches to last, while the Cape weed is flowering, then clean the mower before using it again.