Capeweed (Arctotheca calendula).
Capeweed, is also known as the Cape Dandelion, and is an annual weed with a low growing, flat 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 its habitat.
- Know the best options to control the Cape dandelion.
In cool, cloudy weather, nitrates can rise to high levels in the Cape dandelion. These nitrates then suppress plant Magnesium and iodine levels and cause tetany. Milk may also become tainted when dairy cattle eat this weed.
Why is Capeweed a Problem?
- It has a deep taproot. This enables it to survive in dry conditions.
- The Cape Dandelion produces a lot of seeds and these can remain viable for several years. Under favourable conditions it produces over 4000 seeds a season.
- These seeds move by human activity, animals, wind, water and also in grass clippings.
- The rosettes of Capeweed are large. This means that the plants are able to 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 with 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). | 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, branches. Leafless or have minimal leaves. | Club shaped and sometimes hairy | Yellow. Composed 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 | 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 | 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.
- The Cape Dandelion is an annual weed that germinates in the Autumn and the Winter.
- After it rains, most of the seeds germinate within a few weeks.
- In warm temperatures, Capeweed grows and smothers other plants in the early Winter.
- The rosette is up to 60 cm across, and these large plants are difficult to control with herbicides.
- It has broad, deeply lobed, succulent, leaves. These have a cover of white furry hairs on their underside.
Category: The Cape Dandelion is a Broadleaf (Dicot) weed.
Flower: Capeweed flowers in the late Winter and the Spring. You can often see this weed in Canberra by the side of roads as a bright flush of yellow flowers.
The flower heads look like a Daisy, and the flower 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 plant produces over 4,500 seeds.
- If you don’t carry out regular control measures, weed populations quickly spread and take over.
- When it dies off over the Summer months its own seedlings can establish in the bare areas.
- The woolly seeds stick to clothes, and also spread by the wind.
- This woolly coating also helps with the early germination of this weed.
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 of Capeweed.
- If you have just a small or relatively new Capeweed infestation, you can simply dig it up by hand.
- Take care to make sure that you remove all the plants before they flower. This stops them from dropping seeds.
- 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. If you mow at a low enough height of cut it prevents the weed from flowering.
Weed Management Calendar for Capeweed.
Management Calendar for Capeweed | ||||||||||||
Annual | ||||||||||||
Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
Germination | ||||||||||||
Seeding | ||||||||||||
Active Growth (Rosette) | ||||||||||||
Flowering | ||||||||||||
Seeding | ||||||||||||
Dies Off | ||||||||||||
Pre emergent | ||||||||||||
Post emergent Herbicide | Post emergent (when rosettes form, and before it flowers) |
Chemical Control of Capeweed.
Capeweed is difficult to control with post emergent herbicides as its cover of wooly hairs make it hard to wet.
This means that when you use post emergents 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 the Cape Dandelion.
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 such as Dicamba and MCPA. Once it is present in lawns, best control is to use herbicides that contain 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. Be aware that it will re-grow after this 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. They also have a long term residual effect and will stop re-growth of Cape Dandelion.
- Renegade. Renegade stops seed germination for up to 12 months. This 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.
Table of Non Selective Herbicides for Capeweed.
Product | Active | Chemical Group | Rate/Ha |
Glufosinate 200 | Glufosinate-ammonium | 10 | 1-6L |
Rapid Fire 800 | Glyphosate | 9 | 0.9-1.35 Kg |
Numchuk Quad | Terbuthylazine + Glyphosate + Amitrole Oxyfluorfen | 5 + 9 + 34 + 14 | 20-25L |
Cortex Duo | Nonanoic Acid + Oxyfluorfen | 14 | 7L/1000L |
Renegade | Bromacil | 5 | 3.5-6.5Kg |