Khaki Weed (Alternanthera pungens).
Khaki Weed (Alternanthera pungens) is also known as Creeping Chaff weed. It is originally from South America, and is a Summer creeping perennial with a deep taproot and spiny burrs.
The burrs injure people and animals, and cause hay fever, asthma and skin redness. Khaki Weed is a declared weed in VIC, NT and SA.
After you read this, you will be able to:
- Identify Khaki weed in your lawn or turf area.
- Know what conditions favour its establishment and growth.
- Know how to control this weed.
Why is Khaki Weed a Problem Weed?
- Alternanthera pungens forms a thick ground cover.
- Its is a prodigous seed producer.
- It is difficult to control and able to survive drought becuase of a deep taproot.
- Khaki Weed has spiny burrs that injure people and animals.
- It causes hay fever, asthma and dermatitis.
- It contaminate crops and devalues wool.
The distribution map of Khaki Weed in Australia is courtesy of The Atlas of Living Australia.
How to Identify Khaki Weed (Alternanthera pungens).
The easiest way to recognise Khaki Weed:
- A matt forming weed.
- It has reddish prostrate stems have fine teeth with soft, silky hairs. The stems are up to 60 cm long. and develop roots where the stem nodes touch the soil.
- Khaki Weed has dark green leaves that are in opposite pairs of unequal size. These are 1 to 4 cm long, and 1 to 2 cm wide.
- The leaves are egg-shaped, hairless or sparsely hairy leaves.
- It has cream flowers in clusters, that are 6 to 10 mm long and have sharp points.
- It often has a black taproot.
Photosynthetic Pathway: Khaki Weed is a C4 weed.
Flower: From Spring to Autumn, Khaki Weed produces small clusters of flowers in the leaf forks. As these mature they develop sharp points at their tips and prickles at their base.
The unobtrusive flowers have a cream colour, and have an oval shape. At the base of the flowers are barbed hairs. The fruit is a chaff-coloured prickly burr about 1cm long.
Height: Khaki Weed is prostrate weed.
Leaf length: The hairless leaves of Chaff Weed are 1 to 4 cm long.
Leaf width: The leaf width is 1 to 2 cm, and the leaves do not have stalks.
How Does Khaki Weed Spread.
- Khaki Weed spreads by seeds that stick to tyres, clothing and animals.
- It produces large numbers of seed that remain viable for many years.
- Localised spreading occurs via stems that root at the stem nodes. These often form extensive mats.
- The taproot and stems develop over the Spring and the Summer, and in late Summer the above ground parts all die off. The following Spring it produces new growth from the tap root.
Comments: The leaves have prominent veins on their underside. Khaki Weed produces a deep taproot that it uses to store carbohydrates for emergence and growth in subsequent years.
Habitat: Alternanthera pungens prefers tropical and subtropical regions. It is widespread in waste areas, caravan parks, and playing fields.
Khaki weed is a strong indicator of light, high moisture soils over the Spring and Summer, and is in our weed ID Chart.
It tolerates drought periods due to its deep taproot and waxy leaves.
How to Control Creeping Chaff weed.
Cultural and chemical control will control Khaki Weed in your lawn and turf. You need a long-term control program ito manage Khaki Weed because of the high numbers of persistent seeds seeds and the robust tap root.
An effective control strategy will includes both mechanical and chemical controls.
Cultural Control of Khaki Weed.
- Practice good hygiene if you use machinery in infected areas.
- Hand removal works as long as you remove the crown and the taproot, and you must make sure that you remove all root material. If you break the taproot of Khaki Weed when you try to remove it, new plants grow from any material left in the soil. Aim to dig down 100 mm or more beside the root. Remove and destroy any burrs.
- Regular mowing stops the localised spread of Khaki Weed. This is becuase it depletes the plants carbohydrate reserves.
- Mowing after post emergent herbicide applications ensures even better results than herbicides alone.
Chemical Control of Khaki Weed.
Khaki Weed grows from roots and seeds, so you get the best results if you treat it before it seeds.
Pre- Emergent Control of Khaki Weed.
Applications are most effective during its initial germination when the soil temperatures are about 16 to 21°C.
- Indaziflam.
- Pendimethalin.
Post Emergent Control of Khaki Weed.
Applications to Khaki Weed should start in the Spring when plants are small and actively growing. Make follow up applications around 4 weeks later or when the plants begin to re-grow.
- It is best to apply selective post-emergents when Khaki Weed is growing strongly and not under stress. Ideally you should aim to treat seedlings, as these are most susceptible to chemical treatment.
- Due to its waxy leaves we recommend you use a non-ionic surfactant to maximize herbicide efficacy. We suggest Optispread 1000.
- The aim is to make repeat treatments until you eradicate the Khaki Weed. Products that combine two or more of the ingredients listed below are more likely to provide control.
- Sequential applications of Metsulfuron, around 4 weeks apart, provides the most consistent season-long control.
Several herbicides control Creeping Chaff weed in turf and lawns.
- Casper. Do not use Casper on Buffalo grass.
- Weed Blast MA.
- Duke 100WG.
- ProForce Contra M. Do not use Contra M Buffalo grass.
- Warhead Trio.
- Dicamba. Do not use Dicamba on Buffalo grass.
- or 2,4-D Amine.
- In the USA Trifloxysulfuron (Recondo 100WG) is registered for Khaki Weed control.
Non Selective Control of Khaki Weed.
You cannot use any of these on lawns or turf areas to selectively remove Khaki Weed.
- Glufosinate-ammonium provides control for 4 to 6 weeks, but it regrows and recovers due to the limited movement of glufosinate.
- Glyphosate. You can use Glyphosate but if water quality is an issue then use ProForce Manta Ray.
These are non-selective but also have a long term residual and stop any re-growth of Bindii.
- Renegade. Renegade stops germination for up to 12 months.
- Numchuk Quad. This gives post and pre emergent Alternanthera pungens control for up to 12 months.
- Cortex Duo. Cortex Duo gives a rapid knockdown of Khaki Weed, and residual control for up to 3 months. It is also safe to use around trees.
$310.00
ProForce Cortex Duo Industrial Herbicide is a non glyphosate weed killer. It is both a non-selective knockdown & a residual herbicide. You can use this to kill seedling & young
$140.00 – $295.00
ProForce Renegade 800WG is a preemergent soil herbicide for up to 12 months control of grass & broadleaf weeds in industrial areas & public rights-of-way.
$180.00
Rapid Fire 800SG is a non-selective herbicide contains 800g/kg of the active ingredient glyphosate. It controls a wide range of perennial and annual weeds in a range of situations that
$350.00
ProForce Weed Blast MA Herbicide is a post-emergent broadleaf herbicide, for use on a range of established turfgrass species that includes Couch, Qld Blue Couch, Kikuyu, Paspalum, Buffalo, Fescue, Bent
$115.00
Syngenta Casper Turf Herbicide is a selective post-emergent herbicide. It controls broadleaf weeds in turf and contains the actives Dicamba and Prosulfuron. Do not use on Buffalo Turf.
$150.00
ProForce Warhead Herbicide is a premium selective herbicide and an equivalent to Turf Control, Spearhead and Javelin herbicides. It gives outstanding control of broadleaf weeds in turf.
$220.00
ProForce Contra M Herbicide is a broad-spectrum weedkiller giving quick kill of broadleaf weeds & it controls 38 weeds in turf. Do not use on Buffalo Turf.
$80.00 – $430.00
Numchuk Quad is a non-selective knockdown and residual herbicide. It gives post and pre-emergent weed control for up to 12 months.
$225.00
2,4-D Amine is a selective broadleaf herbicide for weed control in lawns and playing fields.
$270.00
Dicamba 500 Selective Herbicide controls broadleaf weeds in turf, pasture, & Non-crop Areas. Do not use on Buffalo turf.
