Macquarie Valley Weeds Committee & Lachlan Valley Weeds Advisory Committee


Galvanised Burr

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Botanical Name: Sclerolaena birchii
Other Common Names:


  Not Declared
Landholder Responsibilities: The plant must be controlled where it impacts on normal agricultural practices including cropping and pasture management.
Why Is It Bad?: A native of Australia, Galvanised Burr usually occurs within areas of 300-500mm average annual rainfall. Known as a 'pioneer' species, Galvanised Burr is often the first plant to colonise a site affected by drought, overgrazing or cultivation. After rain events, it will germinate quickly and dominate sites. However, if no follow-up rain is received then numbers will naturally decline as seedlings do not tolerate water-stress. Burrs do not seperate themselves from the plant so seed dispersal is achieved through livestock or vehicles breaking stems off or the plant dies and becomes a roly-poly.


Habit: Herb
Leaves: Bluish-green, obovate, flat, 12-18mm long and 4-7mm wide. Leaves are densely wooly/hairy on both surfaces, as are stems, giving the plant its characteristic 'galvanised' appearance.
Flowers: Flowers are bisexual and occur singularly in the leaf axil. Flowering is almost constant, there is no fixed season.
Fruit: Fruit is 2-3mm in diameter, wooly with 4-5 spines. Spines are almost horizontal with the shortest grouped together. The longest spine is 5mm. The fruiting body provides the seed with a level of dormancy as the the burr needs to be penetrated in order for seeds to germinate.
Roots: Taproot to 80cm with shallow secondary roots. The crown has basal buds that reshoot if plant is defoliated.

Control Methods

Manual Removal: Scattered plants or small patches can be hoed out, while larger infestations can be bulldozed. It is important to collect all the removed plant matter for destruction. All cleared sites should be replanted with desirable species to reduce germinations of Galvanised Burr.
Chemical Use: Cut-stump method is useful for killing the crowns of bulldozed plants. Dicamba can be used for high volume spray while 2,4-D amine and dichlorprop can be used on young, actively growing plants.
Fire: Sprayed or removed plants should be burnt to kill seeds and crown.
Slashing & Cutting: Slashing is not recommended as plants will regrow from crown and stem fragments will spread seed, increasing infestation size. Use of machinery will also help break seed pods, increasing germinations.
Biological Control: Natural predators exist as this species is native to Australia.
Grazing: Grazing os seedlings younger than 6 weeks can be an effective control method.
Cultivation & Scalping: After sites have been cleared of large infestations, soil can be ploughed to bury any remaining seed at least 5cm before sowing with desirable species. This method has increased effectiveness if repeated.
Competition: Pasture improvement programs should be introduced after removal of any Galvanised Burr infestations.
Monitoring: Successful treatment programs rely on ongoing monitoring of sites. Regrowth and new seedlings can easily become larger infestations if follow-up treatments are not part of the management program


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Image Credit: Michael Burrowes

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