Capeweed (Arctotheca calendula)

Photo: Buntysmum
Photo: Buntysmum

Family: Asteraceae

Growth Habit: Capeweed grows as a low growing rosette of heavily lobed leaves, the undersides of which are covered with woolly down. As a seedling it is fairly inconspicuous. It is very noticeable in late spring and early summer with its increase in size and the profusion of large yellow daisies.

Type of Plant: Herbaceous annual. Plants germinate in late autumn, flower in late spring, early summer and die off over the summer, leaving bare patches in pastures and lawns.

Flowers: Large, yellow, daisy-like flowers with black centers.

Fruit/Seed: Mature seed is covered a pink, hairy covering.

Dispersal: Seeds are spread by birds and animals, and as a contaminant in soils on vehicles and machinery. It will spread easily in areas of bare soil.

Distribution: Capeweed is a troublesome, widespread weed in Tasmanian pastures, crops, home gardens and disturbed sites like building sites and roadsides.

Status: Although Capeweed seems to be a constant source of worry to Tasmanians it is not a declared weed. Because seedlings are inconspicuous, many landholders do not realize that they have a problem until it begins to flower. While this is the best time to identify the weed, it is difficult to control at this time of year. Forward planning is needed to eradicate it when it is most vulnerable.

In some areas of Tasmania, Capeweed is a significant food source for sheep and cattle. Beekeepers regard Capeweed as an important source of pollen at a time of year when they are trying to build up their hives for the summer honey flows.

Weed Impact:

  • Although stock will eat Capeweed, it is of lower nutritional value than many good pastures. Plants die off after flowering decreasing the food supply available to stock and leaving bare patches that allow more invasive weeds to establish.
  • Stock have died from nitrate poisoning after grazing on Capeweed growing on highly fertile soils. Milk from dairy cows feeding on the weed can have tainted milk. Horses and donkeys can have allergic skin reactions to the pollen encountered as they graze on the plant.
  • Capeweed is able to compete well with agricultural crops and can create problems in home gardens and lawns. The best ways to avoid Capeweed infestations are to keep pastures vigorous and healthy, to avoid practices that disturb the soil and leave bare patches, and to check for seedlings from early autumn onwards when they are easier to control.

Similar Plants: Seedlings of Capeweed can be mistaken for other species such as storksbill (crowsfoot), bittercress, and mustards. However, the black centered daisy flowers are fairly unmistakable.

For further information on Capeweed visit the Department of Primary Industry, Parks, Water and Environment, website.

Control Methods:

  • Integrated control (all year). To effectively control capeweed, several methods should be implemented under a long-term management plan. A combination of chemical and non-chemical control plus follow up should give best results.
  • Pasture management (all year). Establish tough competition such as subclover or perennial grasses.
  • Grazing (late autumn – spring). Heavy grazing during winter and spring can help control capeweed. Stock find the plant more palatable during early flowering. Under grazing can promote capeweed growth, as stocks prefer to eat other grasses and clover. Heavy grazing in late summer and early autumn is not recommended as this may leave patches of bare soil where capeweed seedlings colonise. Where capeweed comprises the majority of the pasture species, avoid prolonged grazing as stock may accumulate toxic levels of nitrate.
  • Cultivation (autumn – spring). Cultivation can be effective if the root system is exposed and allowed to dry out.
  • Grubbing (autumn – spring). Excellent where only small or light infestations occur. Loosen the surrounding soil with a fork, then lift taking care the entire root is intact. Best done when soil is moist.
  • Herbicides. Spot spraying should be used for small patches and boom spraying for larger areas. Several herbicides are registered for capeweed in Tasmania including MCPA, Dicamba, Glyphosate and 2,4-D. Spray-graze technique with MCPA or 2,4-D can be quite effective.

N.B. Always check the herbicide label before use.