Italian cockleburr (Xanthium italicum)

Also known as: Hunter burr

Italian cockleburr is an annual plant that produces a woody burr. It is found in coastal and northwest slopes areas. It is very similar to other Xanthium burr species.

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How does this weed affect you?

Italian cockleburr competes with summer crops and pastures. In crops such as cotton, corn and soybeans, it can out-compete crops for moisture and nutrients. Left untreated, infestations result in reduced yields and downgrading of grain due to contamination. Burr weeds also cause problems in livestock production. Large plants can create barriers for livestock and people around watercourses and in irrigation areas. The burrs can cling to livestock, making handling difficult and causing physical injury to people and the livestock.

Where is it found?

Italian cockleburr is native to the southern United States of America, Mexico and West Indies. Italian cockleburr was first found in the Hunter Valley but has now been found on the central, south and most commonly the northwest slopes and plains.

How does it spread?

Italian cockleburr is an annual plant that reproduces by seed contained in a burr. The burrs are usually dispersed from the plant in autumn and winter but they may remain attached on undisturbed plants until the following spring.

Seeds germinate when the soil is moist in late winter to summer. Flushes of germination can occur after summer storms or irrigation events. On flood prone areas large germination events are common after floods.

What does it look like?

Italian cockleburr is a stout, erect, single stem or many branched annual plant with large leaves similar to those on grapes. Mainly growing in summer, they can grow up to 1 m high. Italian cockleburr, Noogoora burr, California burr and South American burr share this description. However, there is extensive variation between these species, especially in the number and length of the burrs and the spines on the burrs.

Stems

Italian cockleburr plants tend to be single stemmed when growing in dense patches. Isolated plants have branched and spreading stems. Stems are green and rough.

Leaves

Italian cockleburr has grapevine-like leaves that grow alternately on the stems.Both upper and under surfaces are green and rough.Their shape is broad ovate to triangular, cut in 3 lobes.

Fruit (burrs)

The main way of distinguishing between Xanthium burr species is by the burr shape and size. The fruit or burr of the Italian cockleburr is hard and woody, 25-30 mm long, more or less egg-shaped. It is densely covered with hooked spines and ending in longer terminal spines (or beaks) 5-7 mm long that curve inward at the tips. The burr turns brown when mature.

Acknowledgements

Contributing authors: Annie Johnson, Bob Trounce.

Technical reviewers: Graham Charles, Stephen Johnson and Bruce Auld.

References

Cotton CRC (2002) WEEDpak a guide for integrated management of weeds in cotton. Eds Stephen Johnson, Graham Charles, Ian Taylor and Grant Roberts. Cotton CRC, Narrabri.

Hocking PJ. and Liddle MJ 1995, Xanthium occidentale Bertol. complex and X. spinosum L. In Groves RH, Shepherd RC H and Richardson RG (eds), Biology of Australian Weeds, vol 1. RG and FJ Richardson Publishers. Melbourne, pp. 241-289.

National Herbarium of NSW. PlantNET – FloraOnline. www.plantnet.rbgsyd.nsw.gov.au. Accessed 27 March 2008.

Parsons, WT and Cuthbertson, E G (1992) Noxious Weeds of Australia, 2nd ed. CSIRO publishing.

More information

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Control

Prevention of seed set is the most important part of managing Italian cockleburr and eliminating infestations. Trials have shown that six years prevention of seed set leads to a decline in populations to 1% of previous populations. Repeated control is often needed as many germination events can occur from late winter to summer. Early control can prevent competition with crops and pastures, and later control can prevent seed set of plants that may have been missed by earlier control efforts. Large populations can be treated with herbicides, cultivation or slashing; follow-up control of smaller populations may include spot spraying, chipping (or hand-hoeing) or inter-row cultivation in crops. 

Cultivation

Cultivation is an effective method of controlling the seedlings of these weeds. Successive flushes of seedlings during the summer may require follow up control. Inter-row cultivation is commonly used in row cropping such as sorghum, corn and cotton to control seedlings that have germinated after irrigation events.

Slashing

Slashing or mowing are useful in clean-up operations after spraying with herbicide or if infestations are small and scattered. Any burrs from the plant should be removed from the equipment to prevent spread.

Chipping

Chipping or hand hoeing is only economical for small areas, individual plants or isolated populations. It is an effective follow up control method for plants not controlled by other methods to prevent seed set.

Surveillance

After controlling burr plants it is important to monitor these sites for further germination events. High risk areas for new infestations include flood prone areas or areas where stock from burr infested areas have been.

Pasture management

Maintaining ground cover in pastures is vital. Pasture gaps result in an increase in burr germination and seedling survival. It is important to ensure that pastures are not overgrazed in spring and summer to reduce the potential for the establishment of burrs and other weeds.

Grazing

Adult plants are not easily eaten by livestock, due to the roughness of the leaves and stems. Care needs to be taken when grazing to ensure there are no seedling plants, which are toxic to animals and could result in death.

Herbicides

These plants are susceptible to a range of foliar and residual herbicides. 

Foliar herbicides are most effective if the plants are young and actively growing. Plants suffering from moisture stress are difficult to kill. Older plants may require repeat applications. Late control with some herbicides, when the burrs are green, can result in seed sterility – however this is not recommended as the primary form of control.

In crops, residual pre-emergent herbicides are useful, although there are sometimes problems as the burr can germinate and emerge from relatively deep in the soil, below the residual herbicide band. Follow-up control in the form of chipping or inter-row cultivation may be required. Spot spraying is an important tool for areas that are difficult to access and for scattered plants.

Herbicide options

See Using herbicides for more information.

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2,4-D amine 625 g/L (Various products)
Rate: 0.8 – 1.1 L/ha
Comments: Boom spray. Seedlings only.
Withholding period: 7 days withholding for grazing
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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2,4-D LV ester 680g/L (Estercide® Xtra)
Rate: 800 mL/ha
Comments: Boom spray application, from seedlings to pre-flowering. Use higher rates as plants mature
Withholding period: Do not graze or cut for stock food for 7 days after application.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the 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 2015