Hydrocotyle (Hydrocotyle spp)
Hydrocotyle is also known as Pennywort, Dollar Weed and Kurnells Curse. It is a perennial weed, a problem in lawns and turf, and favours wet soils. It has this name because of the shape of its leaves, which resemble a dollar, or a lily pad.
Dollar Weed is a prostrate, aggressive ground-creeping plant. Lest untreated, Hydrocotyle tends to form a dense mat which outcompetes any existing vegetation.
Hydrocotyle has horizontal creeping stems, and it roots at each node. When you crush it, it gives off a strong odour.
After you read this, you will be able to:
- Identify Hydrocotyle.
- Know the habitat of Hydrocotyle.
- Know the best cultural and chemical options to control Pennywort.
For more information, please check out our weed ID chart. Hydrocotyle is a good indicator weed of wet soils.
Thanks to The Atlas of Living Australia for the distribution map for Hydrocotyle.
Hydrocotyle Identification.
Pennywort has a large taproot and many small taproots.
Category: Hydrocotyle is a broadleaf (Dicot) weed.
Photosynthetic Pathway: C3 Weed
Flower: Hydrocotyle has yellow or white flower. These can be present all year round, but are mainly seen from October to February.
Height: Pennywort is a prostrate weed.
Leaf Width: The leaf blade is circular to elliptical, and are 25 to 50 mm in diameter.
Reproduction: Hydrocotyle reproduces via seeds, rhizomes, and sometimes by tubers.
Comments: The dull green leaf of Dollar Weed has a roughly scalloped edge. The leaf divides into distinct segments.
Hydrocotyle is often mistaken for Kidney Weed. A good way to tell them apart is to look at where the leaf stem joins the leaf. The stem of Kidney Weed is at the edge of the leaf, while the Hydrocotyle stem is at the centre of the leaf.
Habitat: Hydrocotyle favours moist soil conditions, and thrives in weak, thin turf.
The image below is courtesy of Clemson University.
How to Control Hydrocotyle.
Cultural control of Hydrocotyle.
Cultural or mechanical means of removal are generally unsuccessful. However, you can consider the following:
- Do not over water and fix any drainage issues that cause wet soils. Low areas that don’t drain very well are ideal for Dollar Weed so deal with low spots etc.
- The University of Florida has shown that if you reduce the irrigation frequency it results in less Hydrocotyle.
- Mow at the right height for your turf grass. A dense, thick turf cover goes a long way toward controlling Hydrocotyle.
- If shade is an issue manage this. Shaded areas tend to remain damp for longer.
- Hand removal of Hydrocotyle does not work well. Usually the weak leaf stem snaps off, and leaves the underground stem behind.
Hydrocotyle on Bowling Greens.
On a sandy, well drained bowling green or golf green over watering is normally the problem. Growth of Hydrocotyle is most aggressive in damp areas, so if you remove even very slight hollows and don’t overwater it will discourage Hydrocotyle.
When you mow and lower the height of cut, the leaves tend to be smaller. In unmown areas the leaves are larger, being up to 20 mm in diameter.
Chemical control of Hydrocotyle.
Pre-Emergents for Hydrocotyle.
Both of the following are registered for Hydrocotyle in the USA.
- Gallery.
- Indaziflam (Specticle)
These are pre-emergent herbicides that provide some control of Dollar Weed in warm-season turfgrasses, but are not currently registered for this in Australia.
Post Emergent Control.
Choose the right herbicide for your turf type and use these in the late Spring and Autumn when Pennywort is small and are growing. Herbicide effectiveness is reduces as weeds mature.
You will need several applications to control Hydrocotyle, as one treatment does not deal with this weed.
- Dicamba. (Do not use Dicamba on Buffalo grass).
- Casper Herbicide. (Do not use Casper on Buffalo grass).
- Warhead Trio
- 2,4-D.
- Contra M. (Do not use Contra M on Buffalo grass).
The options below are registered for hydrocotyle in the USA but not in Australia.
- Quinclorac.
- Clopyralid.
- Rimsulfuron.
- Trifloxysulfuron.
Non Selective Control of Hydrocotyle.
You can control Kurnell Curse if you use non-selective herbicides like glyphosate. Be aware that this kills all vegetative material. Other non selective options like Cortex Duo and Numchuk Quad also kill Hydrocotyle, but then prevent anything growing back for between 3 and 12 months respectively.
- Glyphosate (Rapid Fire 800).
- Cortex Duo and
- Numchuk Quad.
If you use Glyphosate to spray for Hydrocotyle, and water quality is an issue, then add ProForce Manta Ray to your spray mix
