Capeweed (Arctotheca calendula)

Capeweed, also known as the Cape Dandelion, is notoriously difficult to control and is poisonous and indigestible if eaten in large quantities. In livestock, it causes respiratory issues and stringhalt in horses. The three reasons it is a major weed problem are:

• It has a deep taproot that allows it to survive in dry conditions.
• Capeweed produces a lot of viable seeds that remain in the soil for several years. Under unfavourable conditions it can produce over 4000 seeds. These seeds move by human activity, animals, wind, water and in grass clippings.
• It is very competitive and competes for water, nutrients and light.

After you read this, you will be able to:

• Identify Capeweed or the Cape dandelion.
• Know the habitat of Capeweed.
• Know the best options to control Cape dandelion.

In cooler, cloudy weather, nitrates rise to high levels in the Cape dandelion. These nitrates then suppress magnesium and iodine levels and cause tetany. Milk may also become tainted when dairy cattle eat Capeweed. On top of all this, it is an aggressive competitor for water, light and nutrients.

It is an annual and germinates in autumn/winter. Once rain falls, most of the seed germinates within a few weeks. In warm temperatures, capeweed grows and smothers other plants in early winter. In fact, a Capeweed rosette can be up to 60 cm in diameter diameter and out-compete other plants. These large plants are difficult to control with herbicides.

Capeweed flowers form in late winter and spring and produce woolly seeds that stick to clothing and effectively spread the weed through traffic and wind. This woolly coating helps with early germination.

Capeweed, is an annual weed that germinates in the autumn/winter. It is stemless, and forms a dense rosette aboot 50 cm in diameter. It has broad, deeply lobed, succulent, leaves, which are covered in white furry hairs on the underside.

Category: Broadleaf (Dicot).

Flower: The ‘daisy’ looking flower head is made up of several small yellow flowers. It is is 15 mm in diameter and has a black-to-brown centre. These flowers appear on individual stalks about 200mm long.
Height: It grows up to 30 cm in height.
Leaf length: Leaves are 5-25 cm long.
Leaf width: Leaves are 2-6 cm wide.

Reproduction: Capeweed spreads by seeds.
Comments: It produces about 4,500 seeds per plant.

Habitat: Capeweed is present on most soil types but prefers sandy soils and loams. Its presence is a good indication of high soil P levels or high N. More on lawn and turf grass weeds is in our weed ID chart.

Several post-emergent herbicides are available for Capeweed control. At Gilba Solutions, we recommend ProForce Warhead Trio, Weed Blast MA and ProForce Contra M herbicides. (Don’t use Contra M on Buffalo grass.)

Non selective options include Glyphosate (Rapid Fire 800). If you use this and water quality is an issue then we recommend the use of ProForce Manta Ray.