Bromus catharticus Vahl.
Synonyms - Bromus schraderi, Bromus stamineus, Bromus unioloides, Bromus willdenowii, Ceratochloa cathartica, Ceratochloa unioloides, Festuca unioloides.
Bromus is the Greek word for oat.
Other Names:Brome grass
Summary:A luxuriant annual or perennial grass with almost hairless leaves and an open, drooping seed heads and much flattened, awnless spikelets.
Leaves:Emerging leaf rolled in the bud.
Blade - Parallel sided to the middle then tapers to a fine point. 50-420 mm long x 2-12 mm wide. Hairless or sparsely hairy on the upper surface only or young leaves may be covered in short hairs. Rough to touch especially on the upper side, edges and ribs. Flat.
Ligule - Membranous. Ragged. Usually short but can be up to 8 mm long.
Auricles - None.
Sheath - Tubular. Sheath on lower leaves may be densely hairy, On upper leaves it is hairless and rough to touch.
Stems: Densely tufted. 400-1000 mm tall. Erect, rarely bent at the nodes. Stout. Hairless. Unbranched. Smooth. Obvious pigmented nodes.
Flower head:Open, pyramidal panicle or reduced to a raceme. Erect or slightly drooping. 100- 400 mm long with long, rough to touch, thread-like branches, to 150 mm long, usually paired or in rings of up to 3 around the main stalk and rough or slightly hairy branchlets and drooping to one side under the weight of one to several spikelets.
Flowers: Spikelets - Very flattened, oblong to lance shaped. 20-35 mm long x 4-6 mm wide. 6-12 florets, closely overlapping. On stalks (20-40 mm long) and nodding. Oblong to lance shaped. Pale green. Rough to touch.
Florets - Bisexual. 18-22 mm long. Short inconspicuous awn.
Glumes - Persistent. Hairless. Pointed tip. Obvious keels. Rough to touch on keel. Lower one 9-12 mm long, 5-9 nerved. Upper one 13-18 mm long, 7-9 nerved, tiny bristle at the tip. Hairless.
Palea - 2 keeled. 9-10 mm long. Rough to touch along keels.
Lemma - Upper lemmas are not spreading. 9-22 mm long including awn. Broad egg to lance shaped with a pointed tip and sharply keeled. Hairless or occasionally hairy. Papery, especially along the nerves. 9-13 nerved, tip pointed and papery. Closely overlapping initially. Rough to touch. Sharply keeled. Awnless or with an awn or sharp tip 1- 7 mm long, arising just below the top. Awn circular in cross section and not flattened near the base.
Stamens - 3.
Disarticulates above the glumes and between the florets.
Pale, grooved, oval, 8-22 mm long x 2-4 mm wide. Tip pointed. Base pointed. Hairy at the tip.
Key Characters:Glumes 5-9 nerved. Upper lemmas not spreading. Flattened spikelets.
Annual, biennial or perennial. Seeds germinate from autumn to spring. Flowers September to January.
Physiology:Grows rapidly during the winter to spring period especially in irrigated areas.
Flowering times:Spring to early autumn.
Mainly September to December in SA.
September to November in WA with occasional flowers up to January.
Seed Biology and Germination:Vegetative Propagules:
Population Dynamics and Dispersal:
Tends to disappear under continuous grazing.
Origin and History:South America.
Introduced as a pasture grass.
Distribution:ACT, NSW, QLD, SA, TAS, VIC, WA.
Courtesy Australia's Virtual Herbarium.
Habitats:Areas not subject to prolonged grazing. Prefers moist shady places.
Soil:Prefers moist soils.
Plant Associations:Prefers shady situations.
Highly palatable winter and spring feed but often fails to persist. Introduced as a pasture grass from South America.
Irrigated winter pasture grass.
Detrimental:Weed of roadsides, rotation crops, perennial crops, grasslands, disturbed areas, orchards and gardens.
Toxicity:Not recorded as toxic, but high nitrate levels have been measured which could lead to nitrate toxicity if eaten in quantity by hungry animals.
Management and Control:In pastures, graze heavily early in the season to reduce establishment and in spring to reduce seed set. Burn grassy stubble. Increase P, K and trace elements and reduce N applications. Plant competitive pasture species.
Preventing seed set for 1-2 years will provide control. Mowing and cultivation is usually effective whilst burning is more variable. 500 mL/ha of glyphosate(450g/L) applied when the grass is very young or flowering is fairly selective in native vegetation, cheap and effective. Both an early and late application may be needed. For hand spraying, use 10 mL glyphosate in 10 L water and spray until just wet.
Selective control amongst broad-leaved plants can usually be achieved with 100 mL/ha Verdict®520 or 800 mL/ha Fusilade®Forte or 500 mL/ha quizalofop(100g/L) plus 1% spray oil. For hand spraying, use 100 mL of spray oil plus 2 mL Verdict®520 or 16 mL Fusilade®Forte or 10 mL quizalofop(100g/L) per 10 L water.
In bushland areas replant shrub and tree species if necessary to provide shade and help stop re-infestation.
Avoid introducing new seed in contaminated produce.
Herbicide resistance:None reported.
Biological Control:Related plants:
Drooping Brome (Bromus tectorum) is mainly in Victoria and NSW and not recorded in WA.
Great Brome (Bromus diandrus var. diandrus and Bromus diandrus var. rigidus)
Madrid Brome (Bromus madritensis) tends to occur in drier areas.
Mediterranean Brome (Bromus lanceolatus) is not naturalised in WA and occurs mainly in Victoria and SA.
Prairie grass (Bromus catharticus)
Red Brome (Bromus rubens) tends to occur in drier areas.
Sand Brome (Bromus arenarius) is a native species.
Soft Brome (Bromus hordeaceus = Bromus mollis = Bromus molliformis)
Weedy Brome (Bromus alopecuros) Occasionally found in wheatbelt areas.
Plants of similar appearance:Bromus brevis of NSW is very similar but has shorter pedicels (less than 20 mm and usually around 5 mm long) and a more erect seed head.
References:Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P39. Photo.
Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P137. Diagram.
Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P30. Diagram.
Ciba Geigy (1981) Grass Weeds 2. CIBA GEIGY Ltd, Basle, Switzerland. P33. Diagrams.
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P71. Photo.
Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P305.
Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).
Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). 200.2.
Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P945.
Moerkerk, M.R. and Barnett A.G. (1998) More Crop Weeds. (R.G and F.J. Richardson, Melbourne). P29. Photos. Diagrams.
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