Carrot Weed (Cotula australis)
Thanks to The Atlas of Living Australia for the distribution map for Carrot Weed.
After you read this, you will be able to:
- Identify Carrot Weed, Annual Buttonweed or Bachelor’s button.
- Know what conditions favour Annual Buttonweed.
- Know the best cultural and chemical options to control Carrot Weed.
Carrot weed is often confused with Bindii and Swinecress as it has much divided (carrot-like) hairy leaves.
- Swinecress has a skunk-like smell whereas Bachelor’s Button has no odour.
- Carrot weed begins to produce pale yellow flowers on the end of stalks in early Winter, whilst Bindii flowers much later, and has no flower stalks.
Over Autumn and Spring, the seed germinates and then this weed quickly grows. From late Winter to Spring, the plant produces flower stems, and then flowers. As Summer closes in, annual plants usually die or the top growth dies if they are perennials.
Bachelor’s Button is a prostrate, low-growing weed, although it can grow up to 12 cm tall.
The flower heads are button-like and yellow or white with no ‘petals’. From Spring to Autumn the flowers are on slender stalks.
How to Identify Carrot weed.
Photosynthetic Pathway: C3 Weed.
Flower: Carrot Weed flowers in Winter to late Spring, and are white and yellow green in colour.
How to remove Carrot weed from your lawn.
Cultural and chemical options control Carrot Weed, Cotula, Bachelor’s Button or Annual Buttonweed.
Cultural control of Carrot Weed.
If Bachelor’s Button isn’t a major problem, you can remove it by hand. However, you need to remove all of the root system to prevent regrowth.
Carrot weed likes damp, moist soils. So deal with any drainage issues and don’t over water. If the soil is compact, carry out a soil aeration programme. This allows air exchange, and helps excess water move out of the rootzone.
Chemical control of Carrot Weed.
Pre-Emergent Control of Carrot Weed.
Envu Esplanade is registered in Australia for Carrot Weed, and Envu Specticle in the US.
In the USA, Isoxaben is recommended prior to germination, followed by 12 mm of irrigation.
Post Emergent Control of Carrot Weed
- 2,4-D
- Clopyralid
- Dicamba and
- Rimsulfuron
Interestingly, Casper Turf Herbicide is labelled for Carrot Weed in South Africa at 800 g to 1 Kg/Ha but not in Australia.
Non Selective Control of Carrot Weed.
Non selective options for Carrot Weed include Glyphosate (Rapid Fire 800).
If you use Glyphosate and water quality is an issue then we recommend the use of ProForce Manta Ray.
In conclusion
A native weed, Carrot Weed favours moist soils. So the first step to manage this weed is to identify any drainage issues. The second step, before you apply any weed killer, is to maintain a healthy turf surface.
