Capeweed (Arctotheca calendula).
Capeweed, is also known as the Cape Dandelion, and is an annual weed with a low growing, flattened rosette of leaves. It is very difficult to control, poisonous and indigestible if eaten in large quantities. In livestock, it causes respiratory issues and stringhalt in horses.
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.
Why is Capeweed a Weed?
- 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 favourable conditions it produces over 4000 seeds.
- These seeds move by human activity, animals, wind, water and in grass clippings.
- The rosettes of Capeweed are large, and the plants compete strongly with turf grass.
- It is very competitive for water, nutrients and light.
During its vegetative stages, you can confuse Capeweed with Dandelion, Catsear, Sowthistle and Fleabane.
Table of the Differences between Common Rosette Weeds.
Plant | Rosette | Annual or Perennial | Stems | Leaves | Flower Colour | Comments |
Capeweed | Yes | Annual | Several branched stems with small hollow core | Hairy undersides | Yellow with black centre | |
Dandelion | Yes | Perennial | Single unbranched and hollow. Leafless or have minimal leaves. | Deeply toothed or lobed (point backwards) and emit a milky sap when broken. | Single Yellow flower per stalk, made of many small florets | When the stem or leaves are cut exudes sap. Open up when the sun is out, and then close at night. |
Catsear | Yes | Perennial | Multiple, branched.Leafless or have minimal leaves. | Club shaped and sometimes hairy | Yellow. Made up of numerous tightly packed florets. | Catsear has milky sap in its stems and leaves.Needs sunlight for the flowers to open in the morning. Once open can't close for at least 3 hours. |
Gazania | Yes | Annual | Leafless flower stem | Hairless on the upper surface, woolly white hairy underneath. | Yellow | |
Fleabane | Yes | Annual, Biennial or short lived Perennial | Starts as a rosette and then grows tall, upright flower stems. | Elongated with bluntly toothed to deeply lobed margins. | Small tufted white daisy like flowers | |
Oriental Hawksbeard | Yes | Annual | Single leafy, branched main stem. | Hairy and emit a milky sap | Yellow | |
Sowthistle | Yes | Annual | Has branched, hollow stalks | Adult leaves are serrated and deeply lobed with a major triangle-shaped lobe at the tip of the leaf. | Yellow with several flowers per stalk | Open up when the sun is out, and then close at night. |
How to Identify Capeweed.
- Capeweed is an annual weed that germinates in the Autumn and Winter.
- Once it rains, 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 is up to 60 cm across. 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 flower head of Capeweed looks like a Daisy, and is made up of several small yellow flowers. It is 15 mm across and has a black-to-brown centre. The flowers are on individual stalks about 200 mm long.
Height: It grows up to 30 cm in height.
Leaf length: The leaves of Capeweed are 5 to 25 cm long.
Leaf width: Capeweed leaves are 2 to 6 cm wide.
How Does Capeweed Reproduce?
Capeweed spreads by seeds, and a single capeweed plant produces over 4,500 seeds. This means if you don’t carry out regular control, weed populations quickly spread and take over. When it dies off over the summer its own seedlings establish in the bare areas.
The woolly seeds of Capeweed stick to clothes, and also spread by the wind. This woolly coating also helps with early germination.
Habitat: This weed is present on most soil types but prefers sandy soils and loams. The presence of Capeweed is a good indicator of high soil P or N.
More on lawn and turf grass weeds is in our weed ID chart.
How to Control Capeweed.
Cultural Control:
- If you have just a small or relatively young Capeweed infestation, you can simply dig it 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 mow close to the ground to prevent Capeweed from flowering
Chemical Control of Capeweed.
Capeweed is diffilcult to control as its cover of wooly hairs make it hard to wet. This means that with post emergent herbicides you need a wetter to ensure good herbicide contact and uptake. We recommend Optispread 1000.
Pre-Emergent Herbicides for Capeweed Control.
There are several pre-emergents that either suppress or control Capeweed. Be aware that you cannot use Envu Esplanade on turf grass areas.
Suppression of Capeweed.
- Pendimethalin (ProForce Battalia 435) suppresses Capeweed.
Control of Capeweed.
- Prodiamine – Syngenta Barricade 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. Once it is present in lawns, best control is by using herbicides containing dicamba.
- You can kill young rosettes with MCPA or 2,4-D.
- ProForce Warhead Trio. This is safe to use on Buffalo grass.
- Weed Blast MA. This is safe to use on Buffalo grass.
- Casper Turf Herbicide. Don’t use Casper Turf Herbicide on Buffalo grass.
- ProForce Contra M. Don’t use Contra M on Buffalo grass.
Table of Post Emergent Herbicide Rates for Capeweed.
Product | Active | Chemical Group | Rate/Ha | Comments | ||||
Casper | Prosulfuron + Dicamba | 2 and 4 | 800g-1Kg | Apply from Autumn to Spring. Use high rates in cool months or if high weed pressure. Control takes 4 to 6 weeks. Use an NIS at a rate of 0.25 to 0.5% v/v. | ||||
Contra M. | Dicamba + MCPA | 4 | 6.5 L | Apply in 250-400L water. DO NOT use on Buffalo grass. After use do not mow for 2 days before or after application or fertilize within two weeks. | ||||
Dicamba | Dicamba | 4 | 1.2L + 3.2L of 2,4-D Amine 625g/L | Use a minimum of 1000L/Ha water. Do not spray on Buffalo or Bent Grass. | ||||
MCPA | MCPA | 4 | 930ml -1.8L | Apply in high volume to actively growing weeds. DO NOT mow for 2 days before application. Some transitory damage may occur to fine turf grasses | ||||
2,4-D | 2,4-D | 4 | 1.8-3.2 | Wet foliage thoroughly. DO NOT mow lawn for 1 week before and at least 1 weed after application. DO NOT use on Buffalo grass (WA only). | ||||
Weed Blast MA | Bromoxynil + MCPA | 6 + 4 | 3-6L | Apply in a minimum of 500L/Ha water. DO NOT mow for 2 days after treatment. | ||||
Warhead | MCPA + Clopyralid + Diflufenican | 4 + 12 | 5 L | You may see discolouration on kikuyu, carpet grass and Queensland blue. Avoid overlapping. Use an NIS. | ||||
Non Selective Control of Capeweed.
- Glufosinate-ammonium provides control for 4 to 6 weeks, but Capeweed regrows due to the limited movement of glufosinate.
- Glyphosate. You can use Glyphosate but if water quality is an issue then use ProForce Manta Ray.
The following are non-selective but also have a long term residual and stop re-growth of Cape Dandelion.
- Renegade. Renegade stops seed germination for up to 12 months, and reduces the need for multiple herbicide applications.
- Numchuk Quad. This gives effective post and pre emergent Capeweed control for up to 12 months.
- Cortex Duo. Cortex Duo gives a rapid knockdown of Cape Dandelion, and residual control for up to 3 months. It is also safe to use around trees.
