Capeweed (Arctotheca calendula)

Capeweed, also known as the Cape Dandelion. It is very difficult to control and is poisonous and indigestible if eaten in large quantities. In livestock, it causes respiratory issues and stringhalt in horses.

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.

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.

Capeweed, is an annual weed that germinates in the Autumn and 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, the rosette of Capeweed can be up to 60 cm in diameter diameter, and out-compete other plants. These large plants are difficult to control with herbicides.

It has broad, deeply lobed, succulent, leaves, that have a cover of white furry hairs on the underside.

Category: Broadleaf (Dicot).

Flower: Capeweed flowers form in late Winter and the Spring. You can often see this weed in Canberra along the roadside as a bright flush of yellow flowers.

The ‘daisy’ looking flower head of Capeweed is made up of several small yellow flowers. It is 15 mm in diameter and has a black-to-brown centre. These flowers appear on individual stalks about 200 mm long.

Height: It grows up to 30 cm in height.

Leaf length: The leaves of Capeweed are 5-25 cm long.

Leaf width: Leaves are 2-6 cm wide.

Reproduction: Capeweed spreads by seeds, and a single capeweed plant produces over 4,500 seeds. This means if you don’t carry out regular control measures, weed populations can quickly spread and take over.

The flowers of Capeweed produce woolly seeds that stick to clothes and effectively spread the weed through traffic and wind. This woolly coating also helps with early germination.

Comments: Capeweed produces about 4,500 seeds per plant.

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

If you have just a small or relatively young Capeweed infestation, you can simply dig them up by hand. Take care to make sure that you remove plants before they flower to stop them from dropping seeds.

This is because Cape Dandelion seeds can germinate the following year, and for up to seven years after that. To prevent re-growth, make sure that you cut the fleshy taproot well below ground level.​

Mowing is only effective if you repeat this regularly and close to the ground to prevent flowering

Capeweed is diffilcult to control as it is difficult to wet due to its cover of wooly hairs. This means that with post emergent herbicides you will need a wetter to ensure good herbicide uptake. We recommend Optispread 1000.

Pre-Emergent Herbicides for Capeweed Control.

There are several pre-emergent herbicides that will either suppress or control Capeweed. Be aware that Envu Esplanade cannot be used on turf areas.

Suppression of Capeweed.

• Pendimethalin (ProForce Battalia 435)

Control of Capeweed.

• Prodiamine – Syngenta Barricade, Onset 10GR or Spartan Herbicide
• Envu Esplanade Herbicide.
• Envu Specticle Herbicide.

Post Emergent Herbicides for Capeweed Control.

Several post-emergent herbicides are available for Capeweed control such as Dicamba and MCPA.

At Gilba Solutions, we recommend ProForce Warhead Trio, Weed Blast MA, Casper Turf Herbicide and ProForce Contra M herbicides. Don’t use Contra M, Dicamba or Casper Turf Herbicide on Buffalo grass.

Non Selective Herbicides for Capeweed.

Non selective options for Capeweed include Glyphosate (Rapid Fire 800), Numchuk Quad and Cortex Duo.

If you use Glyphosate and water quality is an issue then we recommend the use of ProForce Manta Ray.