Barley grass

Hordeum leporinum Link

Synonyms - Hordeum murinum, Critesion leporinum.

Family: - Poaceae (Gramineae).

Names:

Hordeum is the Latin name for Barley.
Barley grass refers to it membership of the Barley genus.

Other names:

Hare Barley
Common Foxtail because its seed head looks like a fox tail.
Wild Barley

Summary:

A relatively hairless, soft annual grass with bristly, fox-tail like seed heads. It is a widespread weed of crops, pastures and roadsides and flowers in spring.

Description:

Cotyledons:

One.

First leaves:

Grow singly, similar to later leaves.

Leaves:

Tend to be a paler green than most other annual grasses, are often more strongly twisted and often yellow due to frost, disease or nitrogen deficiency.
Leaves rolled in the shoot.
Blade - 40-200 mm long by 1.5-12 mm wide, parallel sided tapering to a pointed tip, parallel veins. Lower leaves often hairy or rough to touch. Upper leaves may have a few fine, soft hairs on both surfaces or rough to touch.
Sheath - Hairless or few fine hairs, especially on the lower leaf sheaths. Uppermost sheath is swollen.
Ligule - Short and membranous, 1 mm long, flat topped and often ragged.
Auricles - Encircle the stem.

Stems:

100-500 mm tall, erect, spreading or bending upwards, tufted, bent at the nodes, round and hollow with solid nodes, often branched at the base. Hairless. Nodes usually hidden in the leaf sheaths.

Flower head:

Narrow, dense, cylindrical, spike like, 30-100 mm long by 10 mm wide excluding the awns, bristly, initially held in the sheath and may remain partly enclosed in the sheath at maturity. Central axis (rachis) has hairs.
Spikelets in sets of three at each node of the rachis.

Flowers:

Spikelets - 10 mm long excluding the awns, hairy. Central spikelet fertile, 1 flowered, stalkless and smaller than the lateral, usually male, shortly stalked ones.
Florets - of central spikelet, 8-10 mm long and has a 1-2 mm long stalk.
Glumes - Rigid, channelled, narrowed into a rough awn that is 10-25 mm long. Glumes of central spikelet and inner glumes of lateral spikelets are lance shaped, 3 nerved and have hairs on the edges. Outer glumes of lateral spikelets are bristle like and rough to touch.
Palea -
Lemma - Lemma of central spikelet, lance shaped, 8-12 mm long with a straight, terminal awn that is 20-40 mm long and rough to touch. Lemma of lateral spikelets, broad, 16-20 mm long with a 20-40 mm long, rough awn. Lemmas are longer than the glumes.
Stamens -
Anthers - Pale brown to brown, poke out of spikelet at maturity, same length on all spikelets and 1-2 mm long. Occasionally the anthers of the outer florets may be up to twice as long as those of the central floret.
Spikelets fall in a group of three and the sharp base (joint of the rachis) pierces skin.
Breaks at the spike axis (rachis).

Fruit:

Falls as a unit of the 3 spikelets containing one seed. There are 3 awns that are much longer than the other awns.

Seeds:

Have rough bristles of varying lengths. Compact oval shaped seed head with many seeds.
Seed weight/head was 0.005-0.012 g. 25.4 seeds/head from 27.5 spikelets/head with 92% fertility. Seeds from the centre of the head were heavier than peripheral seeds (513).

Roots:

Large fibrous root system.

Key Characters:

Auricles encircle the stem. Awn on central spikelet of trio is shorter than the other two. Set of three spikelets fall together. Anthers of central spikelet are pale brown to brown (not black) and exerted. Anthers of all spikelets about the same length.
On young plants the distinctive seed is usually still attached to the roots.

Biology:

Life cycle:

Annual grass. Germinates in autumn and winter. Flowers late-winter to spring

Physiology:

Adaptation to low P situations is due to it relatively slow growth (514). However, fertilizing with P in Temora, NSW lead to barley grass predominance in a clover based pasture (515).

Reproduction:

By seed.

Flowering times:

Mainly September to November in SA.
Spring to early summer in western NSW.
October to December in NSW.
Spring in WA.
September to October in Perth.
Flowering date is related to the length of the growing season (516).

Seed Biology and Germination:

Some innate dormancy but it is normally lost before the autumn and few seeds remain to germinate in winter, spring or subsequent seasons (517) though a few seeds may germinate up to October (518).
77 % germination at 3 days and 93% after 32 days and lighter seeds have a lower germinability than heavy seeds (513)
Optimum temperature for germination is 10-15 deg C. No seeds germinate at 35 deg C and viability is not lost (517).
519 had good germination at constant temperatures from 8-30 deg C but better germinations with alternating temperatures and barley grass germinated faster than annual ryegrass. Barley grass withstood prolonged wetting at high temperatures without loosing viability and soaking for 10 hours and redrying seed increased the rate of germination (519).
Germination of dormant seeds was increased by physical damage, GA and alternating temperatures (517).
Burial in the soil and high field temperatures did not induce dormancy (518).
Of five species of barley grass H. glaucum was the most dormant and H. murinum the least (517).
Seed with husks had an after ripening period of 60-145 days and for de-husked seed it was 45-83 days (520).
Surface mulch stimulates germination (521).
Osmotic potentials of up to 10 atmospheres had little effect on barley grass germination but severely reduced annual ryegrass (519) which is probably why it tends to predominate in slightly saline areas.

Vegetative Propagules:

None.

Hybrids:

Hexaploid forms can't be distinguished morphologically from the diploid forms (522).

Allelopathy:

Population Dynamics and Dispersal:

It is one of the first grasses to germinate after the autumn rains.
Flowering is delayed in heavily grazed situations.
Seed attaches to passing animals by the small barbs on the awns of the glumes and then the set of 3 spikelets penetrates the fur or wool with the tough sharp base which was the joint of the rachis.
Barley grass build up in pastures was more likely to be driven by soil consolidation and pH than N levels created by previous clover stands (523).
Continuous grazing reduces perennial grasses and favours barley grass (524) and more grazing reduces it in annual pasture systems 521.
Nutrients affect composition in pastures (525) but 521 found soil N status didn't affect proportion of barley grass in the pasture. Barley grass responds poorly to applied N compared to annual ryegrass and Vulpia species (526) so in mixed stands it tends to be reduced with increasing N status. Each kilogram of N applied resulted in 9.6 kg increase in barley grass and a 21.4 kg increase in annual ryegrass (527).
The initial production (about 4 weeks) from barley grass is greater than annual ryegrass because of it larger seed size and faster germination, but ryegrass growth rates are faster so it is more productive later in the year (528).
In barley grass and annual ryegrass mixtures, barley grass predominates at low N levels and ryegrass at high N levels(526).
Barrel medic did not compete successfully with barley grass under grazing in NSW (529).
In clover/annual ryegrass pastures, barley grass tends to predominate at the lower stocking rates where addition phosphate has been applied (530).
531 has nutritive values and production levels over the season.
Barley grass was worse on areas grazed by merinos compared to Dorset horn sheep and Merino ewes and lambs were severely infested with seed while the no Dorset horn ewes and few lambs were infested (532).

Origin and History:

Mediterranean. South-eastern Europe (522).
First collected in the 1840's (516).

Distribution:

ACT, NSW, NT, QLD, SA, TAS, VIC, WA.
Algeria (533),New Zealand (534), Syria (533),USA (535)

Courtesy Australia's Virtual Herbarium.

Habitats:

Climate:

Temperate. Mediterranean.
Winter rainfall areas.
Tends to be the predominant "barley grass" in areas with an annual rainfall greater than 425 mm/year in Victoria, South Australia and NSW where it grows as far north as Sydney (516).

Soil:

Most abundant on heavier soil types.
Occurs on a wide range of soils from deep sands to heavy clays.
Tends to predominate on low P soils (514).

Plant Associations:

Tends to be more abundant in under grazed pastures.

Significance:

Beneficial:

Pasture fodder valued for early season production. Best production was with rotational grazing and resting periods of less than 45 days (536).
Does not host Root Lesion Nematode (Pratylenchus neglectus) (63).
Some biotypes are resistant to Rhynchosporium secalis (537).

Detrimental:

Weed of crops causing yield loss.
Weed of pasture with seeds causing damage to skins, carcases and eyes of stock, matting and contamination of wool and decreased bodyweight (538). Injuries can be fatal to lambs.
Weed of fallows, rotation crops, coastal islands and disturbed areas.
It is a poor host for Root Lesion Nematode (Pratylenchus thornei) allowing some build up of numbers (63).
It is a good host for Root Lesion Nematode (Pratylenchus thornei) allowing rapid build up of numbers (63).
Host for barley scald (539), eyespot of wheat (540), Powdery Mildew, Net Blotch (but 541 reports the isolates from barley grass in WA did not infect barley), Take-all and a form of stripe rust.

Toxicity:

Lambs may die from damage due to seeds.
Seed injuries to eyes cause the greatest growth check, and injury to gums, nostrils and skin were also important (542), especially if they become infected. Lambs are ten times more vulnerable than adults with up to 8 kg/lamb loss of growth over summer and there were big differences between breeds (542). Crossbreds get more grass seed and less medic burr contamination than denser wool merinos (543)
Seed may collect in the shoulders, groins and feet of sheep impairing their ability to walk and forage especially in lambs. Live weight loss in lambs is attributed to reluctance to walk rather than intake per se (543).
May cause photo sensitisation in sheep.
Pollen may cause hay fever in people in early spring.

Legislation:

None.

Management and Control:

Paddock should be heavily grazed until seed heads start to turn yellow. Sheep should then be removed to prevent damage and wool contamination. In 4-12 weeks most seed will have fallen and infestations can usually be grazed with little damage. Lambs especially should be shorn if on contaminated pastures as this reduces the number of seeds penetrating the skin (543).
Continuous grazing to keep pasture short eliminates barley grass in 2 years, whereas rotational hard grazing took 3 years to eliminate it and lax grazing over summer helped reduce establishment in the following season (544). In NSW doubling the stocking rate from 2.5 to 5 dse/ha led to a reduction in barley grass in pastures (521) or high stocking rates in 545 trials. Heavy grazing in autumn reduces barley grass but this may lead to increased storksbill whereas heavy grazing in late winter increased barley grass but for heads to be formed close to the ground and reduced harmful effects on stock (546).
Mowing or late grazing provides reasonable control for the following season (547, 548).
Live weights of lambs on barley grass pasture were 6-8 kg lower than those on clean pasture in a NZ study. Control by herbicides reduced total pasture production but increased live weight gains. (Hartley 1975, 1976). Reduced live weights were associated with high barley grass seed set in NSW (545).
Delayed planting of crops allows most plants to be controlled with knockdown herbicides.
Spray topping with fops, glyphosate or paraquat provides good control of seed set (549).

Thresholds:

60 plants/m2 are usually worth spraying in cereals. 100 plants/m2 caused 21% yield loss in wheat (550).

Eradication strategies:

Prevent seed set for 1-2 years by hand weeding, mowing, cultivation or herbicides.
In pastures, heavily graze infestation during winter. Remove stock when the first seed head emerge. Spray top with paraquat just before the first heads start to change colour. Repeat if late rains result in a second emergence of heads. On paddocks that are to be cropped in the following season, hay freezing with glyphosate or cutting for silage then spraying regrowth with paraquat is preferred.
Complete control of seed set results in very low levels of infestation in the following season.
Burning provides some control if done early before the seed falls and starts to bury itself.
Avoid early planting of crops.
The group A grass selective herbicides generally provide high levels of control in broad leaved crops.
In bushland situations, spray with 400 mL/ha Fusilade®Forte or 50 mL/ha Verdict®520 or 250 mL/ha quizalofop(100g/L) plus 1% spray oil in winter when the grass has 2-8 leaves. For hand spraying use 8 mL Fusilade®Forte or 1 mL Verdict®520 or 5 mL quizalofop(100g/L) plus 100 mL spray oil in 10 L water. These treatments are very selective and do not damage broad-leaved native plants.
Alternatively, spray with 10 mL glyphosate(450g/L) in 10 L water when the seed heads are just emerging in spring. Most established natives will tolerate this treatment, but higher rates will cause damage. In sensitive areas where there are seedling native or broad-leaved plants 16 mL Fusilade®Forte or 2 mL Verdict®520 or 10 mL quizalofop(100g/L) plus 100 mL spray oil in 10 L water, applied any time before flowering, when the plants are actively growing, will provide reasonable control of plants and seed set.

Herbicide resistance:

Resistance to paraquat (551), fops and dims has been reported.

Biological Control:

120 mice/ha ate 44% of barley grass seed, however this did not lead to a decrease in barley grass as mice also consumed competing wild oats (552 ,535).
Septoria halophila causes blackish-brown oval to lens shaped lesions, often coalescing on the leaf blade and sheath. Black pycnidia are scattered evenly in the lesions on older leaves. It does not affect barley or wheat (553).

Related plants:

Barley (H. vulgare) has longer stems and much larger seeds.
Mediterranean Barley grass (H. hystrix or H. geniculatum) has no auricles.
Northern Barley grass (H. glaucum or H. leporinum ssp. glaucum) is very similar and often confused. It has black or pale anthers, 0.6 mm long, that remain inside the floret. The anthers are much longer in the lateral florets than the central one. It is more common in the semi arid areas.
Sea Barley grass (H. marinum) tends to grow in saline or wet areas and has no auricles.
Hordeum murinum occurs near Hobart (516) and on the Swan Coastal Plain in WA.

Plants of similar appearance:

Canary Grass (Phalaris canariensis)
Cocksfoot (Dactylis glomerata)
Elephant Grass (Pennisetum purpureum)
Feathertop (Pennisetum villosum)
Hare's-tail Grass (Lagurus ovatus) is similar but hairy.
Slender Foxtail (Alopecurus myosuroides)
Marsh Foxtail (Alopecurus geniculatus)
Meadow Foxtail (Alopecurus pratensis)
Timothy Grass (Phleum pratense)
Annual ryegrass, Barley grass, Brome grass, Darnel, Fountain grass, Guildford grass, Quaking grass, Sand fescue, Silver grass, Volunteer cereals, Wild oats, Toad rush, Winter grass.
Young Barley grass may have hairy leaves and resemble Brome grass

References:

Auld, B.A. and Medd R.W. (1992). Weeds. An illustrated botanical guide to the weeds of Australia. (Inkata Press, Melbourne). P47-48. Photo.

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P141. Diagram.

Burbidge, N.T. and Gray, M. (1970). Flora of the Australian Capital Territory. (Australian National University Press, Canberra). P56-57. Diagram.

Ciba Geigy (1981) Grass Weeds 2. CIBA GEIGY Ltd, Basle, Switzerland. P86. Diagrams.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P110. Diagram. Photo.

Everist, S.L. (1974). Poisonous Plants of Australia. (Angus and Robertson, Sydney). P298.

Gilbey, D. (1989). Identification of weeds in cereal and legume crops. Bulletin 4107. (Western Australian Department of Agriculture , Perth). p8-9. Photos.

Hartley, M.J. (1976). New Zealand Grassland Association Proceedings 37:59-65.

Hartley, M.J. and Bilmer K.H. (1975). Proceedings 28th New Zealand Weed and Pest Control Conference, 2-6.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P56. Photo.

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). #655.4.

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). P965.

McBarron, E.J. (1983). Poisonous plants. (Inkata Press, Melbourne). P4. Diagram.

Paterson, J.G. (1977). Grasses in South Western Australia. (Western Australian Department of Agriculture Bulletin 4007). P55. Diagram.

Wilding, J.L. et al. (1987). Crop weeds. (Inkata Press, Melbourne). P27. Diagrams. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.