Sifton bush (Cassina arcuata)

Sifton bush is a drought hardy perennial shrub. It has become a weed of disturbed areas and degraded native pastures.

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How does this weed affect you?

Sifton bush has a massive seed production and its seedlings establish rapidly on bare ground. In recent years it has spread into more fertile regions where it is able to out-compete degraded pastures that have been thinned or lost due to drought, overgrazing, fire or reduced fertiliser applications. Sifton bush harbours vermin such as rabbits, foxes and pigs and dense infestations can be a fire hazard. Roads can become overgrown with sifton bush making access and stock mustering difficult. In heavy densities sifton bush can substantially reduce carrying capacities (to 0.6 wethers per hectare or even less where ground cover is minimal).

Mature sifton bush is unpalatable to most grazing animals and has been suspected of causing poisoning in lambs. In humans, flowering sifton bush can also trigger allergic rhinitis (hay fever).

Where is it found?

Sifton bush is native to Australia and there are 22 other species of Cassinia found in New South Wales (NSW). Sifton bush is able to grow on naturally infertile, rocky, acidic country. Its native distribution occurs across most of NSW, but it is most problematic in the regions of Central NSW, the Southern Tablelands, the eastern Riverina and the New England North West. It has become a weed of disturbed areas such as graded roadsides, cleared and ploughed areas, and degraded native pastures.

How does it spread?

Seed production is massive. Studies have shown a single mature plant in one square metre is able to produce 4100 million seeds. Seed production per plant decreases with plant density due to the seed heads only forming on the upper reaches of branches (2.6 mature plants/m2 produce 2300 million seeds).

Seeds are not generally dormant and can germinate readily at any time of the year but mostly in autumn. As the seed gets older it becomes less likely to germinate. The viability of seed falls from 60-80% in year one to 0.3% in year 15. Seedlings have long hairs on their primary roots making them well adapted to establishing on the soil surface; however it is difficult for them to emerge from deeper in the soil (see Table 1).

Table 1. Emergence of sifton bush seedlings from soil. (Source: M. Campbell)
Depth of planting (mm)% emergence in 27 days
Surface 59
5 23
10 16
15 2
20 and 40 0

What does it look like?

Sifton bush can grow to a height of 3 m, but most commonly it grows from 1 to 2 m. Mature plants generally have one main stem which branches into numerous smaller stems between 5 and 50 cm above the ground.

Bark on stems is dark grey-brown, furrowed and covered with white hairs.

Leaves are alternate, dark green and slender, 0.4-1.5 mm long, with rounded ends and rolled margins. They are often sticky and covered with matted white hairs on the under surface. When the bushes are bruised the plant emits a distinctive curry or coffee-like aroma.

Identification is easiest when the brown flowering heads are present, drooping on large plants.Cassinia quinquiferia and C. laevis plants have similar flowering heads but their leaves are up to 40 mm long.

Sifton bush seed is very small (0.75 x 0.4 mm; 25 million/kg) and topped with a hairy covering or ‘pappus’ of 25 bristles that are each 2 mm long.

Sifton bush seedlings are very erect and look like ‘mini’ pine trees. They are slow to establish in the first 3 months, but may reach 60 cm in the first year when conditions are favourable. They rarely flower before two years of age.

Flowering occurs from October to May depending on location, for example, flowering in the Orange district typically begins in December when yellow flower buds appear and ends in May when seeds ripen and begin to disperse.

Habitat

Sifton bush is able to grow on naturally infertile, rocky, acidic country.  It has become a weed of disturbed areas such as graded roadsides, cleared and ploughed areas, and degraded native pastures.

References

Ayres L (2011). Sifton bush, Primefact 1135. NSW DPI, Orange. 

Reviewers: Lester McCormick, Birgitte Verbeek, Jo Powells

References

  • Campbell, M. H., Holtkamp, R. H., McCormick, L. H., Wykes, P. J., Donaldson, J. F., Gullan, P. J. and Gillespie, P. S. (1994) ‘Biological control of the native shrubs Cassinia spp. using native scale insects Austrotachardia sp. and Paratachardina sp. (Hemiptera: Kerriidae) in NSW’, Plant Protection Quarterly, Vol 9 (2).
  • Campbell, M. H., McGowen, I. J., Milne, B. R. and Vere, D. T. (1990) ‘The biology of Australian weeds. 22. Cassinia arcuata R. Br’, Plant protection quarterly, Vol. 5(4), pp. 162-168.
  • Campbell, M. H., Milne, B. R., May, C. E., Vere, D. T. and McGowan, I. J. (1998) ‘Cassina arcuata’ in Biology of Australian Weeds, pp 37-47.
  • Cunningham, G. M., Mulham, W. E., Milthorpe, P. and Leigh, J. H. (1992) Plants of Western NSW, CSIRO, Canberra.
  • McCormick, L., Holtkamp, R. and Campbell, M. H. (1996) Biological control of sifton bush and related species, Agnote second ed.
  • McGregor, B. A. and Couchman, R. C. (1988) ‘An evaluation of blitz-grazing management of Chinese scrub (Cassinia arcuata) with cashmere goats or Merino sheep’, Proceedings of the Symposium on Weeds on Public lands, Weed Science Society of Victoria, Monash University, p.48.
  • Semple, W. S. and Koen, T. B. (1993) ‘Some effects of fire on the survival of sifton bush (Cassinia arcuata)’, Rangelands Journal, 15(2) pp. 320-330.
  • Simpson, P. and Langford, C. (1996) Managing high rainfall native pastures on a whole farm basis, NSW Agriculture, Orange.

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Control

The control and management of sifton bush requires ongoing persistence and resources. A range of strategies can be adopted to effectively manage and ultimately reduce the amount of sifton bush infestation on a property.

Prevent establishment in clean country

Sifton bush is often first seen creeping into native grass-based pastures where soil fertility has declined or pastures have been overgrazed over a number of years. Keep native pastures in their most competitive state by maintaining ground cover and not overgrazing, and by allowing native perennial grasses to set seed. Strategic use of fertiliser on responsive native species such as Microlaena or Danthonia will also help to maintain competition and ground cover, and will reduce the potential for new infestations.

The soils in which sifton bush prefers to grow are fragile and vulnerable to infestation when disturbed. Removal of trees and soil disturbance can create ideal conditions for establishment.

Chipping, pulling and brushcutting

Chipping or pulling out isolated or scattered plants is easiest to do when the ground is moist. Avoid excessive soil disturbance if possible.

Brushcutting can be useful on plants greater than one metre tall provided they are cut as close to the ground as possible and the stems of the plant are torn rather than cut evenly across. Rainfall events following cutting can trigger re-shooting from cut stems. In some districts sifton bush has been removed by pulling a wooden sleeper or heavy log behind a tractor.

Slashing and mulching

The effectiveness of slashing is limited to flat or gently sloping land with limited surface rock.

Both blade and chain slashers have been used effectively to kill mature sifton bush. Plants cannot recover when they are cut below the crown, as long as they are more than one metre tall, over two years old and have well defined crowns.

Slashing and mulching smaller bushes is not effective as the machinery often rides over them and does not effectively break the stems, allowing them to re-shoot from damaged stems.

The best time to slash is when soils are dry. Slashing at this time places additional stress on damaged plants and any hot, dry weather following will reduce ability to re-shoot and recover. Care must be taken when slashing to avoid fires caused by the chains or blade connecting with rocks and producing sparks. Slashing should be repeated in two years to control regrowth. One disadvantage of slashing is that the stumps remaining will cause vehicle and motorbike tyre punctures easily until they start to decay.

Other methods such as mulching can work well on older plants by shattering the stems rather than cutting.

Burning

Burning can be used to remove large plants however seedling reinfestation is a major problem after burning. Short duration foliage burns are generally ineffective but can delay seeding for at least one season. As a long term control technique burning is of limited use unless follow-up control of seedlings occurs after burning.

Grazing with sheep or goats

Grazing with sheep or goats is likely to have the biggest impact on young plants, seedlings or regrowth. Mature plants generally only sustain minor damage. For maximum effectiveness paddock size needs to be small and the sifton bush infestation light to moderate. Do not expect grazing animals alone to control sifton bush.

The feed quality and palatability of sifton bush is poor (see Table 2). 

The digestibility (amount able to be utilised by the animal) of the green leaf material is only 49.8%, when compared to legumes which are (70-80%) and green leaf from introduced pasture species (68-75%). Research has shown that forcing merino wethers at high stocking rates (18 dse/ha) to graze a phalaris/sub clover pasture infested with 60% sifton bush over a period of 8 months resulted in a 37% loss of initial liveweight. Non-breeding cashmere goats stocked at 9 dse/ha also lost 28% of initial liveweight but ate more sifton bush than sheep. Non-breeding meat or cashmere goats or first or second cross angoras are the most useful due to their feeding habits and their light fleeces which reduce the risk of snaring. Livestock grazing sifton bush must have access to good quality pasture or supplementary feed in order to maintain animal condition. Be aware of potential animal health problems as sifton bush is suspected of poisoning lambs, causing loss of coordination in the hind-quarters of lambs. Continual grazing of paddocks by stock is likely to result in overgrazing of useful species, creating favourable conditions such as bare ground for the subsequent germination of more sifton bush.

Pasture establishment considerations

Sifton bush is typically found on soil types that may have underlying impediments to sustaining long term pasture production and growth. In such areas pasture establishment may be risky, more likely to fail or not economically viable. Before attempting to spray out and re-sow any new pastures it is essential to carry out a soil test to determine current fertility and nutrient status. Carefully inspect the existing pasture species and landscape features with an agronomist and obtain advice. For more information about establishing pastures see the publications and advice at http://www.dpi.nsw.gov.au/agriculture/pastures/pastures-and-rangelands/establishment

Biological control

The naturally occurring native scale insects Austrotachardia sp. and Paratachardina sp. have been noted killing small areas of sifton bush since 1979. Between 1988 and 1993 in central and north western NSW larger areas of other Cassinia species were killed by the insects. The scale insects can be found by looking for dead or partly dead bushes with black stems (sooty mould) and frantic ant activity. The female scales produce honeydew on which a black sooty mould grows. Paratachardina sp. is brown in colour and Austrotachardia sp. is red or maroon. Mature females of both species appear on stems as raised lumps and range in size from 2-5 mm in diameter.  Often the population of the scales is so dense that it is difficult to recognise individual insects (up to 30 adult females per centimetre of branch). Crawlers (young nymphs) are produced within the body of the female and emerge through an opening in the shell.

In north-western NSW, there is one generation per year with crawlers emerging in November. In central NSW there can be two populations. The first generation crawlers emerge in December and the second generation in March. Seasonal conditions can vary at these times. Females produce approximately 300 crawlers each. The crawlers, less than 1 mm long when they emerge, move up the stems where they settle, insert their mouths through the bark and start feeding on sap. They may also move to adjacent bushes and can even be carried long distances by wind. Once they have inserted their mouths, females remain in that location for the year of their life cycle.

Successful biological control depends on the ability of these insects to colonise new plants as well as their ability to damage the plants they are on. Because adult scales are immobile, their dispersal is restricted to the mobile crawlers that usually only spread over short distances (10 metres) once a year. Landholders can aid the spread of these scales by transporting them over large distances. To be effective, cuttings containing scale insects need to be transferred to uninfected bushes two to four weeks before the emergence of the crawlers.

Cuttings of 7-10 cm in length are ideal, providing they contain good populations of adult female scales. These cuttings are best tied across two or more branches using twist ties. Twist ties do not impede the movement of crawlers, giving them a good chance of relocation. Once the crawlers emerge, the cuttings should be removed and burnt to help control any predators or parasitoids they may contain. It is believed that the inability of the native scale to cause mass damage in some areas may be due to other predators and parasitoids such as small wasps which use the scales as hosts for their offspring.

Under the Native Vegetation Act (2003) some restrictions may apply to the clearing of sifton bush for pasture development. Seek advice from your Local Land Services.

Table 2. Feed quality of sifton bush leaves and stems. Source: NSW DPI Feedtest database
Feed testRange (8 samples)Average
Dry matter digestibility 42-54 49.8
Protein % 3.0-10.5 8.0
Metabolisable Energy MJ ME/Kg 6.3-8.1 7.5

Herbicides

There is a limited choice of chemicals registered for the control of sifton bush. 

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


Glyphosate 360 g/L (Roundup®)
Rate: 1.0 or 1.3 L in 100 L of water
Comments: Apply when actively growing. Ensure complete coverage; use higher rate on bushes over 1 m high.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


Picloram 100 g/L + Triclopyr 300 g/L + Aminopyralid 8 g/L (Grazon Extra®)
Rate: 500 mL in 100 L of water
Comments: Foliar application, plants need to be actively growing for optimal effect
Withholding period: Where product is used to control woody weeds in pastures there is a restriction of 12 weeks for use of treated pastures for making hay and silage; using hay or other plant material for compost, mulch or mushroom substrate; or using animal waste from animals grazing on treated pastures for compost, mulching, or spreading on pasture/crops.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


Triclopyr 300 g/L + Picloram 100 g/L (Grazon® DS)
Rate: 500 mL in 100 L of water
Comments: Bushes need to be actively growing for optimum effect.
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
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 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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Disclaimers

Pasture improvement may be associated with an increase in the incidence of certain livestock health disorders. Livestock and production losses from some disorders are possible. Management may need to be modified to minimise risk. Consult your veterinarian or adviser when planning pasture improvement. The Native Vegetation Act 2003 restricts some pasture improvement practices where existing pasture contains native species. Inquire through the NSW Office of Environment and Heritage for further details.

Reviewed 2014