Barley grass

Scientific name: Critesion spp

Barley grass

Barley grass

Barley grass

Barley grass seed head
  • Key characteristics
  • Biology
  • Impacts
  • Control
  • Further information

  • Annual grass that germinates in autumn and sets seed in summer
  • Seeds have long bristly awns that stick to clothing and wool
  • Before plants flower they can be recognised by the slender but well-developed auricles that often encircle the base of the stem
  • Emerging leaves are rolled and leaves are often twisted
  • Leaves have a few hairs (unlike brome grasses which are very hairy)
  • Ligule is short, white and irregularly toothed.

Origin

  • Originated in the Mediterranean, southwest Europe, and parts of Asia.

Life cycle

  • Annual grass that mostly germinates in autumn and sets seed in summer
  • Germination can occur in spring and plants then produce seed late in a shortened growing season
  • Seeds have little dormancy and most germinate in the autumn following their production. A few can last longer if trapped under dry cow-pats or tree branches.

Critesion species (barley grasses) present in New Zealand

  • Six species of barley grass are present in New Zealand: Critesion glaucum, C. hystrix, C. jubatum, C. marinum, C. murinum and C. secalinum. Differences between the six species are small and they can all be managed in the same way (i.e. same control methods)
  • Barley grass (Critesion murinum) is the most common and inhabits disturbed areas (e.g. stock camps) in pastures, and sometimes in crops. Barley grass is divided into two subspecies murinum and subspecies leporinum: the latter tends to occur in drier areas
  • Squirrel tail grass (C. jubatum) has long soft awns (which may have a pink tinge) and is only found in damp salt pans in Central Otago
  • Salt barley grass (C. marinum) and Mediterranean barley grass (C. hystrix) mostly grow on salt-affected pastures, salty marshes, and coastal areas
  • C. secalinum is a perennial grass, unlike the other five, which are annuals, and is only found near Porangahau in coastal Hawkes Bay.

Benefits

  • Provides good-quality feed in autumn and during winter when plants are in the vegetative stage
  • Used for cover-cropping in Europe, in olive groves to prevent erosion in mountainous areas in Spain, and in vineyards in Turkey. An additional benefit is that barley grass tolerates drought well.

Occurrence

  • Predominately a weed of high fertility soils, although salt barley grass and Mediterranean barley grass are prevalent on low fertility soils
  • Compete more strongly in pastures in nitrogen-enriched soils
  • Prevalent on stock camps, along fence lines and shelter belts and other disturbed or high usage areas where pasture cover is damaged in late summer and early autumn

Impact on pasture

  • Provides low quality forage during late spring as the plants begin to flower
  • Sheep avoid grazing barley grass when the seed heads emerge
  • Avoidance of barley grass places more pressure on better pasture species. Barley grass can tolerate conditions of water stress better than other species and being an annual, avoids summer drought. Perennial grasses on the other hand, will be selectively grazed over summer. Grazing pressure, in combination with water stress, can lead to the decline of perennial species in pastures and reduce their ability to compete against annual grass weeds, such as barley grass. This enables undesirable annual species to gain a stronger foothold over time.

Impact on stock

  • Sharp, awned seeds can penetrate fleeces, pelts, carcasses, hocks, mouths and eyes of grazing livestock
  • If seed contamination is severe, stock growth rates can be reduced
  • Fine wool sheep tend to pick up the seeds more easily than sheep with coarse wool, although the actual skin damage is less in sheep with fine wool
  • Lambs are much more susceptible than older sheep, as their skin is more easily penetrated. They spend more time lying on the ground, which increases the chance of them picking up barley grass seed
  • In 1971 Bob Taylor, a New Zealand farmer, wrote “Since 1966, areas suspected or known to contain appreciable numbers of viable seed have been fenced off, grazed a few times between January and September by sheep which were allowed in only to eat on their feet. This procedure has greatly helped to bring barley grass under control. Only about one new infestation of barley grass appears each year, never containing many plants. In earlier times, as many as a thousand barley grass plants appeared in a new infestation arising from seed carried in the wool of only sixty sheep. Barley grass is no longer collected in sacks, but in very small plastic bags. Half the lamb pelts at one time were punctured, but none are now.”
  • Sheep dogs sometimes pick up barley grass seeds between their toes, leading to sores and lameness.

  • As with most grass weeds, an integrated approach is important with a focus on maintaining a healthy cover of desirable, competitive pasture species – especially in late summer and autumn. Tools for this include grazing management, fertiliser, herbicide and physical removal of plants.

Grazing management

  • Seeds have very little dormancy and do not survive for long in the soil; so that grazing management to prevent seed production can control barley grass within a few years
  • Summer: Identify areas of barley grass infestation from their seed heads and mark the areas on your farm map. Decide on the best method of control for the area depending on access to boom-spray, ease of controlled grazing, potential damage to pelts. (Is the area used for grazing lambs?) Lax grazing during summer helps maintain pasture cover and can reduce barley grass establishment in autumn
  • Autumn: Heavy grazing may be required in paddocks to be treated with herbicides (pastures must be short for some herbicides to work effectively). Removal of standing pasture will also increase access for boom-sprays and other equipment
  • Winter: Rest infested paddocks from grazing if possible. In response, barley grass produces plants with fewer tillers which have their growing points higher from the ground
  • Spring: Graze more heavily. Stock removes the growing point; the tiller dies and no seed is produced. Grazing pressure must be maintained to prevent new tillers and seed heads from being formed, or at least to reduce the height of the barley grass seed heads. This reduces the damage that seeds cause to sheep.

Pasture species/cultivars

  • Some pasture species and cultivars are more resistant to barley grass than others, often because they withstand summer drought better. Novel endophytes can help pastures resist weed invasion and spread. Endophytes can allow pasture species to be more drought tolerant and resistant to insect attack. This enables sown pasture species to grow more vigorously, making it more difficult for weeds to establish. Some high endophyte ryegrass cultivars and low-growing cultivars of   cocksfoot seem to be more effective.

 

Fertiliser application

  • Ensure soil fertility levels are appropriate as this can increase the vigour of sown pasture species and reduce barley grass establishment
  • Note that barley grass is often found on high fertility, disturbed areas such as stock camps, along fence lines, around gate ways and watering points. In these areas, it is difficult for competitive pasture species to establish and suppress barley grass.

Mowing/grubbing

  • Clippings should be collected and dumped securely to prevent the seeds from ripening
  • Small numbers of plants can be grubbed or manually removed.

Chemical control

  • Winter-cleaning: herbicides can be applied during vegetative stage at levels sufficient to selectively kill barley grass plants
  • Spraying barley grass in summer with glyphosate damages pasture species and creates a perfect seed bed for germination of surviving seeds.

 

Herbicides used to control barley grass in pastures include the following:

ALWAYS READ PRODUCT LABELS BEFORE APPLYING

Active ingredient When to apply Residual effect Grass damage Clover damage
paraquat or glyphosate + simazine At the green seed head stage Yes Yes Severe
dalapon Late autumn to early spring during vegetative growth Moderate Slight No
dalapon + TCA Late autumn to early spring during vegetative growth Yes Slight No
ethofumesate Mid-autumn until mid-winter, during vegetative growth Yes Not to ryegrass Severe
propyzamide Winter during vegetative growth Yes Severe No
  • Effectiveness of herbicides depends on:
    • Application rate
    • Soil moisture conditions and plant stress
    • Pasture height and size of plants being sprayed
  • As glyphosate will kill all plants it contacts, patches of bare ground (gaps) are created, this, neither glyphosate nor paraquat are recommended for barley grass control
  • Simazine can be added to glyphosate or paraquat to provide residual control of barley grass (simazine is residual in the soil and prevents seeds from germinating)
  • Ethofumesate can be applied to ryegrass pastures (ryegrass is tolerant to ethofumesate), but ethofumesate kills clovers.

Consult your farm consultant, industry rep or the New Zealand Agrichemical Manual for more information about chemical control.

Suggestion based on size of infestation

Small patches:

  • Remove manually or apply herbicide
  • Note that applying herbicide once flowering has started may allow seeds to form and patches to grow in successive years.

50% paddock cover:

  • Apply herbicide
  • Graze laxly over summer and early autumn so that sown pasture species are not overgrazed. This enables sown species to grow vigorously after autumn rains and suppress barley grass
  • Keep lambs off affected paddocks.

Most of paddock covered:

  • Consider resowing, using recommended species of grasses with appropriate endophytes for the region.

  • Champion P, James T, Popay I, Ford K 2012. An illustrated guide to common grasses, sedges and rushes of New Zealand. New Zealand Plant Protection Society, Christchurch, New Zealand. 208 p.
  • Young S 2013. New Zealand Novachem agrichemical manual. Agrimedia Ltd, Christchurch, New Zealand. 767 p.

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