Dodder (Cuscuta species)

Dodders are leafless, parasitic plants with threadlike stems that twine around host plants. They can kill the host plants and are poisonous to livestock.

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How does this weed affect you?

Dodders are parasitic plants that smother and penetrate the tissues of host plants removing nutrients. Infestations can:

• reduce yields in broadleaf crops, especially lucerne and vegetables
• transmit crop viruses
• contaminate seed, fodder and hay
• poison livestock.

Livestock poisoning

High levels of dodder in fodder are toxic to cattle and horses. Poisoning can occur if horses and cattle are fed contaminated hay for several weeks. Problems are usually only experienced when dodder makes up about 50% of the contents of the hay.

Typical poisoning symptoms include stomach pain, diarrhea and weight loss. Severe poisoning can cause liver damage, internal bleeding and brain damage. The brain damage makes the animal’s behaviour erratic and unpredictable. Brain damaged animals will stagger and wander aimlessly, then lay down, becoming comatose or convulsive and eventually dying.

What does it look like?

Dodder plants have thread-like stems that form a tangled mass around host plants. The leaves are reduced to small scales on the stems. The plants have no roots except for the first few days after germination. Dodders have suckers called haustoria which penetrate the tissues of the host plant.

There are six species of dodder in NSW and three of these are introduced species. The following description is at the genus level for invasive species of dodder found in NSW.

Stems are:

• mostly yellow but may also be reddish or purple
• narrow and thread-like
• hairless
• branched and twined around the host plants.

Flowers are:

• white or cream or pink
• bell-shaped with 3–5 petals
• 3–4 mm in diameter
• in clusters
• mostly present in summer (for introduced species).

Fruit are:

• round capsules containing up to 4 seeds
• 3–4 mm wide.

Seeds are:

• brown, yellow or grey
• 1–2 mm in diameter
• slightly pear-shaped.

Where is it found?

Dodders grow throughout NSW.

The introduced species are present in the following regions:

• Cuscuta campestris (golden dodder) is native to America. It is the most widespread of the dodders in NSW and grows in all regions.
• Cuscuta epithymum is native to Europe and the Mediterranean region. In NSW it mostly grows in the tableland regions.
• Cuscuta suaveolens is native to South America. In NSW it has been found growing in the North West, Riverina and South East regions.

What type of environment does it grow in?

Dodders are parasitic weeds that require a suitable host species to survive. They have adapted to a wide range of environments. Dodders are widespread along rivers, creeks, floodplains and irrigation areas. 

Dodders have been found growing over the following host plants:

• lucerne
• vegetables including tomatoes, zucchini, carrots, celery, lettuce and onions
• legume crops
• other weeds including burrs (Xanthium spp.), wireweed (Polygonum aviculare) and lupins (Lupinus)
• broadleaf pasture plants
• native herbs
• tree seedlings.

How does it spread?

By seed

Dodders grow quickly and can flower and set seed within 3 weeks of germination. Up to 16,000 seeds can be produced from a single plant. Seeds can survive in soil for at least 5 years. Dodder seedlings only have a basic root to anchor it to the soil for a few days. Plants usually need to attach to a host plant within 2-6 days, depending on species and moisture levels. Sometimes seedlings survive several weeks without a host in wet periods.

Dodder seeds are spread:

• in water if still in the capsule
• via irrigation lines, which can pick up small seeds and spread them
• by people dumping garden waste
• in contaminated fodder and pasture seed
• by animals including cows, sheep, goats and kangaroos that accidentally eat and pass the seeds through their gut
• in contaminated mud attached to vehicles, machinery, boots and the feet of water birds.

By plant parts

Stems can spread from the initial host to nearby plants. Dodder plants can also grow from broken fragments which can be spread by moving water, machinery, sticking to livestock or in contaminated fodder. Stem fragments that have withered can regrow if there is a suitable host present.

References

National Herbarium of New South Wales (2007) Cuscuta campestris. PlantNET – FLoraOnline.www.plantnet.rbgsyd.nsw.gov.au (accessed 14/01/2008).

Parker, C. (2008). CABI data Sheet: Cuscuta campestris (field dodder). Retrieved 7 July 2025 from: https://www.cabidigitallibrary.org/doi/10.1079/cabicompendium.17111

Parsons, W.T. and Cuthbertson, E.G. (2000). Noxious Weeds of Australia 2nd ed. CSIRO publishing.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 7 July 2025 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=gn&name=Cuscuta

More information

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Control

Dodder is difficult to eradicate. Preventing it from entering your property, checking regularly and destroying new outbreaks before they seed is recommended. Begin treatment as soon as possible after an infestation is noticed. Scattered plants can rapidly result in a major infestation which is difficult and costly to control. To manage dodder:

• look for dodder from spring to early autumn
• treat plants immediately with a buffer zone of at least 1 m around any dodder plants
• record treated areas to help you check for regrowth
• follow up until dodder no longer grows

Prevention

Import clean seed and fodder

Sow clean, certified pasture seed. Dodder seeds are small, like lucerne and clover seeds. It is hard to separate if mixed in with other seeds. Only use clean fodder. You can request a fodder declaration form from suppliers. Destroy any hay that contains dodder.

Hygiene

To limit the spread of dodder:

• clean machinery after it has been in an infested paddock
• clean boots and clothing before moving to a new paddock
• do not cut or graze infested areas
• quarantine livestock that have had contact with dodder for at least 2 days before moving to clean paddocks.

Restrict movement in irrigation

Small dodder seeds can be picked up in irrigation suction lines. Use self-cleaning or flushing filters if there is a risk of spreading dodder seed in irrigation water.

Early detection

Look for small threads starting to invade the crop. Small threads up to 5 cm can reattach to the host crop. If dodder is present, control immediately. Mapping infestations at the end of summer will help in checking for reinfestations the following spring. Inspect lucerne paddocks before the first cut. Inspect pasture paddocks after rainfall in late spring.

Buffer zones

Dodder can be spread by seed and stem fragments; therefore it is important to a treat a buffer zone outside the obvious areas of infestation. Look for small threads starting to invade further into the crop.

A buffer zone of at least 1 m from the infestation should be treated with herbicide or burnt. Once treated, infestations should remain marked so the effectiveness of the control can be checked at a later date.

Control host weeds

Wireweed, Noogoora burr (Xanthium occidentale) and Bathurst burr (Xanthium spinosum) are preferred hosts for dodder. Controlling these weeds will help limit infestations.

Hand removal

Removing the plants by hand is only suitable for very small infestations. The host plants need to be removed as well because the dodder grows inside the host’s leaf tissue. 

Slashing and burning

Slashing should only be used prior to burning. Do not cut or slash dodder and leave the cut material in the crop as it will re-attach itself to a new host.

Burning the dodder and the host plant will help eradicate it from the site. It is best to burn it on the infested site.

Cut the host plant as close as possible to ground level and burn as soon as it is dry enough to ignite.Burning is more effective following the application of a desiccant herbicide. The area should be inspected again after one week, as dodder may re-shoot from the crowns of lucerne and weeds such as wireweed, Noogoora burr or Bathurst burr. Hotter burns will achieve higher dodder kill rates but have greater risk of killing host crops. A lucerne stand that has been burnt can regenerate from undamaged crowns without the need for re-sowing.

Consult the relevant authorities prior to undertaking any burning operations.

Crop rotation

Crop rotation can reduce dodder hosts. Replace severely infested lucerne or clover with less susceptible hosts such as:

• cereal crops: wheat, barley, oats, triticale, cereal rye, maize and sorghum
• perennial pasture grasses with subterranean clover as the legume.

Control dodder in summer before sowing a winter cereal. Dodder can persist on weeds in crops and pastures, so control weeds to reduce host plants and maintain a clean fallow. Control broadleaf weeds in cereal crops. Do not sow lucerne or susceptible legumes until the paddock has been clean of dodder for 5 years. Dodder is less likely to establish if lucerne or susceptible clovers are re-sown in late summer to autumn.

Cultivation

Deep ploughing can help reduce the amount of viable dodder seeds by burying them. Most dodder seeds will not germinate from a depth of more than 7.5 cm.

Chemical control

Apply herbicide to host plants in a buffer zone at least 1 m beyond the infested area.

Spot spraying

Spray before the dodder is flowering. Apply to all the foliage on both the dodder andthe host plant.

Herbicide options

See Using herbicides for more information.

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Metsulfuron-methyl 300 g/kg + Aminopyralid 375 g/kg (Various products)
Rate: 2 g per 100 L of water plus non-ionic surfactant at a rate of 100 mL per 100 L.
Comments: Spray with a handgun to the point of run-off before flowering. Follow the label instructions as per Golden dodder.
Withholding period: Pastures - Grazing for meat production or cutting for animal feed: Do not graze for 56 days after application. See label for further details
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors) + 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: High/Moderate

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Metsulfuron-methyl 600 g/kg (Various products)
Rate: 1 g per 100 L of water plus non-ionic surfactant at a rate of 100 mL per 100 L.
Comments: Apply as a spot spray to point of run before flowering. Surfactants include BS1000 and equivalents. Follow the label instructions as per Golden dodder.
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: 2 (previously group B), Inhibition of acetolactate and/or acetohydroxyacid synthase (ALS, AHAS inhibitors)
Resistance risk: High

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Biosecurity duty

The content provided here is for information purposes only and is taken from the NSW Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area	Duty
All of NSW	General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.

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Reviewed 2025