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Spiny Burrgrass

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Botanical Name: Cenchrus incertus & longispinus
Other Common Names:

Declarations

 
Class Regions
Class 4Bland Shire Council,Bogan Shire Council,Bourke Shire Council,Brewarrina Shire Council,Cabonne Council,Castlereagh Macquarie County Council,Cobar Shire Council,Cootamundra Shire Council,Cowra Council,Dubbo City Council,Forbes Shire Council,Lachlan Shire Council,Mid-Western Regional Council,Narromine Shire Council,Orange City Council,Parkes Shire Council,Upper Macquarie County Council,Weddin Shire Council,Wellington Council
Landholder Responsibilities: The growth and spread of the plant must be controlled according to the measures specified in a management plan published by the local control authority and the plant may not be sold, propagated or knowingly distributed
Why Is It Bad?: The burrs produced by these species are sharp and easily adhere to wool, fur, clothing, car tyres, and machinery. Burrs can become badly matted in wool, lowering the values of wool clips and making sheep difficult to handle, increasing shearing costs. Burr spines can also penetrate the skin of native animals and livestock, leading to discomfort and stress from the injuries they create. It can also lead to decreased values of hides and increased costs associated with the slaughtering process. The spines can also cause mouth ulcers in grazing animals, leading to overall decreases in health.

Identification

Habit: Grass
Leaves: Leaves are mostly smooth, sometimes wrinkled and twisted. They are 20cm long, 5-8mm wide, and finely serrated with flattened sheathes.
Flowers: Inflorescence is a spike-like panicle, 3-8cm long, with up to 40 burrs.
Fruit: The burrs are straw coloured, with slender spines with broad bases. Spines are sharp, finely barbed and rigid. There are usually more than 40 spines per burr. C. longispinus, as its name suggests, has longer spines reaching lengths of 7mm. C. incertus spines are 2-5mm long. There are usually 1-3 seeds per burr, with approximately 1000 seeds produced per plant. Seeds are smooth, ovoid, 2-4mm long and 2-3mm wide. Some seeds can remain dormant for 3 years while others will germinate within a few months.
Roots: Roots are fibrous and mostly shallow however they can be over 30cm deep in some soil types.

Control Methods

Manual Removal:
Chemical Use: Use of non-selective herbicides can be used to remove established plants but needs to be followed by burning or cultivation to destroy seed heads. This needs to take place over 3-5 years to deplete soil seed banks.
Fire:
Slashing & Cutting:
Biological Control:
Grazing: Spiny Burrgrass is readily eaten during its active growing period, and heavy grazing pressure will suppress growth and burr production. Grazing cannot be used when burrs are present as livestock will not only suffer from the effects of any burrs that attach themselves to the animals, but also will actively spread the weed.
Cultivation & Scalping: If used, this method must take place before seed set occurs; otherwise viable seed will be spread vastly, dramatically increasing an infestation. Seedlings are easier to turn than larger plants. This method must be used in combination with other methods to ensure soil seed banks are exhausted appropriately. Soil seed banks should be exhausted as much as possible before cropping. A winter crop could be used for a few seasons before a summer crop is sowed.
Smothering:
Solarisation:
Competition: Maintaining vigorous perennial pastures will help prevent invasion by Spiny Burrgrass as it does not establish readily where there is strong competition. By ensuring there is sufficient ground cover present during spring and summer, germination and seedling establishment is decreased. Pasture grasses such as Rhodes, Digit and Consol lovegrass (in some areas) species can be used as they grow well in light sandy soils, are palatable to stock, summer growing and drought tolerant perennials.
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.

Images

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Image Credit: Glenn Neyland


Image Credit: Glenn Neyland





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