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CDFA Plant Health

Noxious Weed Photographic Gallery

Jointed goatgrass [Aegilops cylindrica Host.][AEGCY][CDFA list: B] Photographs Map of Distribution

Ovate goatgrass [Aegilops ovata L.][CDFA list: B] Photographs Map of Distribution

Barb goatgrass [Aegilops triuncialis L.][AEGTR][CalEPPC: Need more information][CDFA list: B] Photographs Map of Distribution


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[SYNONYMS] [GENERAL DESCRIPTION] [SEEDLINGS] [MATURE PLANT] [ROOTS and UNDERGROUND STRUCTURES] [SPIKELETS/FLORETS] [Table of Distinguishing Characteristics] [POSTSENESCENCE CHARACTERISTICS] [HABITAT] [DISTRIBUTION] [PROPAGATION/PHENOLOGY] [MANAGEMENT FAVORING/DISCOURAGING SURVIVAL] [SIMILAR SPECIES] [CONTROL METHODS]


SYNONYMS: These species are sometimes included in the genus Triticum.

  • ovate goatgrass: A. geniculata Roth, A. neglecta Req. ex Bertol.
  • barb goatgrass: barbed goatgrass

GENERAL DESCRIPTION: Winter annuals closely related to and resembling winter wheat (Triticum aestivum L.). Goatgrass species hybridize with wheat and are sometimes crossed with wheat to impart adaptive characteristics such as cold tolerance and disease resistance. Field crosses of jointed goatgrass and wheat produce F1 hybrids that are of intermediate form and mostly sterile (to 50%). Jointed goatgrass often infests winter wheat fields and can competitively reduce wheat yields by as much as 25% (54 goatgrass plants/m2 ). Joints tightly enclose the grains and are difficult to separate from wheat grains, lowering the quality and value of the harvest. In addition, jointed goatgrass is an overwintering host for winter wheat pests, such as the Russian wheat aphid (Diuraphis noxia Mordvilko RKO) and several fungal pathogens. Barb goatgrass is primarily a rangeland weed. All species are introduced from Mediterranean Europe and western Asia.

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SEEDLINGS: Typically the joint (section of inflorescence axis and spikelet that contains the seeds) is still attached to the mesocotyl (part of embryonic stalk near the cotyledon) of dug-up seedlings.

jointed goatgrass: Similar to winter wheat, but blades, auricles, ligules, and leaf sheaths with evenly spaced, fine hairs along the margins (ciliate). Coleoptile and first leaf typically reddish to brownish-green. Ligule membranous, 0.5 mm long or less.

  • barb and ovate goatgrass: No seedling descriptions available.

MATURE PLANT: Stems branching at the base and erect, spreading, or abruptly bent near the base. Blades flat, spreading, ciliate, about 2-3 mm wide; lower surface and sometimes upper surface sparsely covered with fine hairs. Sheaths open. Ligule membranous, 0.5 mm long or less, with upper margins finely fringed. Auricles about 0.5 mm long, ciliate, with hairs about 1-3 mm long.

  • jointed goatgrass: Mostly erect. To 50 cm tall. Culms (stems) hollow. Blade upper surfaces often glabrous. Susceptible to rust.
  • ovate goatgrass: Tufted. To 25 cm tall.
  • barb goatgrass: Mostly spreading. To 45 cm tall. Culms solid when young, but become hollow with age. Blades rigid. Not susceptible to rust.

ROOTS and UNDERGROUND STRUCTURES: Roots fibrous. Barb goatgrass roots develop more rapidly and to a greater depth and width than those of soft brome (Bromus hordeaceus L.) or medusahead (Taeniatherum caput-medusae (L.) Nevski), but not slender wild oats (Avena barbata Link.).

SPIKELETS/FLORETS: Spikelets 1/node, alternate, laying flat against and fitting into a groove in a zig-zag rachis. Glume and lemma awns stiff, sharp, and minutely barbed. Glumes and rachis enclose each floret and harden at maturity. Each spikelet and its associated node and rachis is called a joint. Typically there are two 1-seeded fruits (caryopses) per joint. Unlike winter wheat, goatgrass caryopses adhere to the lemma and palea and are difficult to separate from the joint. Caryopses resemble long grains of winter wheat: oblong (+/- oval in ovate goatgrass), reddish- to light brown, grooved, 6-9 mm long, with short hairs at the apex. Refer to the following Table of Distinguishing Characterstics for a comparison of important species differences.

jointed goatgrass: May-June. Spikes cylindric, disperse as units at maturity, but ultimately break apart into joints. Joints cylindric, with blunt ends. Spikelets +/- cylindric, with 2-5 florets, the lower 2 usually fertile. Lemmas of terminal spikelets 1-awned, awns 4-5 cm long, erect. Lemmas of lower spikelets pointed or 1-awned, awns 1-5 mm long. Outcrossing or self-pollinating.

  • ovate goatgrass: May-July. Spikes ovate-cylindric, disperse as units at maturity and do not break apart into joints. Spikelets +/- ovate, usually with 5 florets, the upper 3 sterile. Glume awns of lower spikelets spreading, 2-3.5 cm long. Lemmas of upper spikelets 3-awned; of lower spikelets 2-awned. Lemma awns shorter than glume awns.
  • barb goatgrass: May-July. Immature spikes often reddish or purplish. Spikes cylindric, disperse as units at maturity, but ultlimately break apart into joints. Disarticulated joint ends are sharp and can injure livestock. Spikelets cylindric to +/- ovate, typically with 4 florets, the upper 2 sterile. Glume awns of upper spikelets spreading, 4-8 cm long. Lemma awns short or lacking.

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Table of Distinguishing Characteristics:

 

Spike Length

# Spikelets/
Spike

Upper Spikelets

Awns/Glume
&
Awn Length
of

Terminal Spikelet

Awns/Glume &
Awn Length of
Lowest Spikelet

jointed goatgrass 2-12 cm 3-12 fertile 1; 3-8 cm 0-1; short
ovate goatgrass 1-3 cm 2-4 sterile 3; short 2-5; 2-3.5 cm
barb goatgrass 2-6 cm 2-6 fertile 3; 3-8 cm 2-3; 3-8 cm

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POSTSENESCENCE CHARACTERISTICS: Persistent inflorescences and spikelets of dried grasses and joints on the ground facilitate species identification.

HABITAT: All goatgrass species inhabit dry, disturbed sites, fields, and roadsides. Jointed goatgrass also infests grainfields, especially winter wheat. Barb goatgrass primarily infests rangelands and pastures, including grasslands and oak woodlands, but usually not chaparral. Barb goatgrass tolerates serpentine and hard, shallow, dry, gravelly soils.

DISTRIBUTION:

  • jointed goatgrass: Cascade Ranges, Modoc Plataeu, Sacramento Valley, Southern California, except deserts; to Wa, Mexico, Great Plains. To 1500 m (5000 ft).
  • ovate goatgrass: North Coast Ranges (Mendocino Co., especially near Willits). Expected to expand range. To 500 m (1650 ft).
  • barb goatgrass: Cascade Ranges foothills, southern North Coast Ranges, Sacramento Valley, northern and central Sierra Nevada foothills, Central Coast, San Francisco Bay region, and South Coast Ranges. To 1000 m (3300 ft). Expanding range.

PROPAGATION/PHENOLOGY: Reproduces by seed. Dispersed by livestock, especially sheep, human activities, water (joints float), and wind.

  • jointed goatgrass: Under typical field conditons with adequate moisture, one plant produces about 130 seeds, but isolated plants can produce as many as 3000 seeds. The seeds of each joint are of two types (heteromorphic). The lowest seed in a spikelet is dormant the first fall after maturation, loses dormancy that winter, and becomes dormant again the following spring if it does not germinate or decay. The upper seeds in a spikelet are non-dormant. Seed can remain viable under field conditions for 3 to 5 years, with viability declining rapidly in moist soils due to increased microbial degradation. Seeds germinate in the joints, often on the surface of undisturbed soil. Soil compaction appears to enhance germination and emergence. Under controlled conditions, germination is optimal at 20º C, but possible from 10-35º C. Most germination occurs in fall (mid-September to November), but some spring germination also occurs. Spring germinating plants can mature to produce seed if temperatures are cool enough (~ 3º C or 37º F) to vernalize (chill for a period) seedlings or imbibed seeds. Flowering is promoted by vernalization of imbibed seeds or seedlings under conditions similar to those required by winter wheat (~5-7º C or 40-45º C with 8-10 hr photoperiod for 6-10 weeks). Longer periods of vernalization at 3º C cause plants to flower earlier and increase the number of seedheads per plant. Most emergence occurs from soil depths of 0-5 cm (2-3 cm optimal). Some seed can survive ingestion by cattle.
  • ovate goatgrass: Removing seed from joints increases germination.
  • barb goatgrass: Seeds germinate in the joints in the field, but joints appear to reduce germination. Under experimental conditions, seed germination in the joints was about 41%. Removing seed from joints increased germination to about 91%. Germination occurs under a wide range of temperatures (less than 5º C and greater than 25º C). Some seeds can remain dormant for 2 or more years. Seedling growth is fastest at about 5-10º C.

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MANAGEMENT FAVORING/DISCOURAGING SURVIVAL:

  • jointed goatgrass: Burning winter wheat fields after harvest can reduce germination of joints at the surface by 90% or more. Rotation to spring sown crops for 3 years can limit jointed goatgrass seed production, significantly depleting the soil seed bank.
  • barb goatgrass: Some seed in joints on the ground after dispersal survive controlled field burns because outer portions of the joints protect the seeds. Heavy grazing throughout the growing season and high intensity/short duration grazing periodically during the growing season appear to increase plant density.

SIMILAR SPECIES: Goatgrass inflorescences are distinctive and unlikely to be confused with other weedy annual grasses. In addition, barb goatgrass tends to mature later than most other rangeland annual grasses.

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CONTROL METHODS:

Prevention: Jointed goatgrass is primarily a problem in winter wheat producing areas across the Great Plains and Pacific Northwest. It has been the subject of intensive research, and its biology is well understood. However, it is becoming a problem in winter wheat and rangeland areas in Northern California. Barb goatgrass and ovate goatgrass are also found in rangeland and non-crop areas of Northern California. All three are closely related to wheat (Triticum aestivum) and have been utilized in wheat breeding programs. However, they all exhibit noxious characteristics by vigorously competing with wheat or desirable rangeland and native vegetation. Barb goatgrass may cause severe mechanical injury to livestock. Prevention is the key in dealing with these species, because once they become established, controlling them is very difficult. Goatgrass spread occurs only by seed dispersal, and there are several ways it may be prevented. All three species have long barbed awns, which may be transported on hair, fur, wool, shoes or clothes. Grazing animals should be removed from infested areas before plants mature. Where known infestations exist, animal trails in the area should be monitored for goatgrass spread. Emergence of jointed goatgrass is reportedly favored in somewhat compacted soils, which are common along, roadsides, livestock paths, and game trails. Feeding contaminated wheat straw or unprocessed grain to livestock may increase the spread of goatgrass. Jointed goatgrass seed retain viability of up to 75% after passing through ruminants. Animals fed contaminated straw or unprocessed grain should be confined before moving to new areas. Separating wheat and goatgrass seed is a very difficult and costly process. To avoid planting goatgrass contaminated wheat seed, use certified seed. During the harvesting season, transport trucks should be covered and combines and tractors should be thoroughly cleaned before moving from infested fields. Straw spreaders on combines may also spread goatgrass seed and should not be used in infested areas.

Mechanical: Mowing can be an effective method of reducing seed production. However, the timing is critical. Mowing should occur after flowering, but before goatgrass seeds reach the soft boot stage. Early mowing will result in new tiller growth and late mowing will only spread viable seed. Tillage may be utilized in certain situations. Hand pulling or hoeing small infestations is effective, if the roots are pulled and air-dried. In agricultural fields, sweep tillage or V-blade tillage may be effectively used during fallow (non-crop) periods. Conventional deep plowing will bury goatgrass seed beyond emergence depth. However, buried seed may be viable for up to five years, and burial depth seems to have little effect on jointed goatgrass seed viability or dormancy. Secondary tillage following deep plowing may return buried goatgrass seed to a successful emergence depth (< 5 inches).

Burning: All three species generally mature later than most annual grasses found in rangelands. This may provide an effective window for controlling goatgrass seed production, without compromising desirable annual grass seed production. Recent research has shown some success for barb goatgrass control with an early summer burn. It is important to burn before the joints disarticulate, to ensure seed kill. Burning will not effectively control seed on the soil surface. Dormancy studies of jointed goatgrass indicate seed may be viable in the soil for up to five years. Goatgrass germination may also increase the year after burning due to increased fertility and light penetration. Therefore, a second year management strategy must be incorporated, and the population should be monitored for several years.

Biological: Naturally occurring bacterial strains that infect annual brome and jointed goatgrass, but have no effect on wheat, have been isolated in Kansas and Washington. These bacteria may soon be utilized in a bio-herbicidal approach for jointed goatgrass control in winter wheat. However, their utility in rangelands has not been explored.

Chemical: There are currently no selective herbicides for goatgrass control in cereal producing or rangeland areas. Nonselective herbicides such as glyphosate (0.38-0.75 lb ae/A) may be applied to control small infestations. Applications should be made to non-stressed plants in the spring after goatgrass has tillered but before flowering occurs. A reseeding program of perennial grasses and legumes, or other desirable vegetation should follow spot treatments.

Integrated Management Strategies: In agricultural systems, crop rotation is critical for managing winter annual grass weeds. Where it is economically feasible, fall-seeded cereals should be rotated to a spring-planted crop. This allows for additional nonselective weed management strategies to be used, such as nonselective herbicides, fall cultivation, and preplant cultivation in the spring. Rotating to a broadleaf crop also allows for selective grass control with herbicides. Crop rotation has been the most successful strategy for managing jointed goatgrass. In dryland agriculture where broadleaf crops are not rotated with fall-seeded cereals, maximize goatgrass control in the fallow periods, with tillage and herbicides. In rangeland, burning the first year followed by a herbicide and spring seeding the second year may improve goatgrass control. Monitoring should be employed to detect new infestations and prevent their spread.

References
Anderson, R. L. 1992. Effect of duration of jointed goatgrass interference on winter wheat grain yield. Res.Prog.Rep.West.Soc.Weed Sci. 2-3.
Anderson, R. L. 1993. Crop residue reduces jointed goatgrass (Aegilops cylindrica) seedling growth. Weed Technology 7:717-722.
Anderson, R. L. 1993. Jointed goatgrass (Aegilops cylindrica) ecology and interference in winter wheat. Weed Sci. 41:388-393.
Bailey, K. L., Hucl, P., and Harding, H. 1957. Four interspecific germplasm lines (302-1, 302-3, 302-5, 302-20) of spring wheat with resistance to common root rot (Cochliobolus sativus) derived from Aegilops ovata. Canadian Journal of Plant Science 75:693-694.
Donald, W. W. 1984. Vernalization requirements for flowering of jointed goatgrass (Aegilops cylindrica). Weed Sci. 32:631-637.
Donald, W. W. and Zimdahl, R. L. 1987. Persistence, germinability, and distribution of jointed goatgrass (Aegilops cylindrica) seed in soil. Weed Sci. 35:149-154.
Donald, W. W. 1991. Seed survival, germination ability, and emergence of jointed goatgrass (Aegilops cylindrica). Weed Sci. 39:210-216.
Donald, W. W. and Ogg, A. G. 1991. Biology and control of jointed goatgrass (Aegilops cylindrica), a review. Weed Technology 5:3-17.

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3/18/15