Agropyron cristatum
(crested wheatgrass)

Pictures

Picture	Title	Caption	Copyright
Title Habit Caption Agropyron cristatum (crested wheatgrass); habit, Montana, USA. Much of what passes as Montana steppe (prairie) actually comprises mostly few grass species that withstand long histories of overstocking, such as Agropyron cristatum (crested wheatgrass), Agropyron dasystachyum (thickspike wheatgrass), and Stipa comata (needle and thread grass). Copyright ©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0	Habit	Agropyron cristatum (crested wheatgrass); habit, Montana, USA. Much of what passes as Montana steppe (prairie) actually comprises mostly few grass species that withstand long histories of overstocking, such as Agropyron cristatum (crested wheatgrass), Agropyron dasystachyum (thickspike wheatgrass), and Stipa comata (needle and thread grass).	©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Title Habit and spikes Caption Agropyron cristatum (crested wheatgrass); habit and spikes. USA. Copyright Public Domain/released by USDA-NRCS PLANTS Database/Cassondra Skinner	Habit and spikes	Agropyron cristatum (crested wheatgrass); habit and spikes. USA.	Public Domain/released by USDA-NRCS PLANTS Database/Cassondra Skinner
Title Habit and spikes Caption Agropyron cristatum (crested wheatgrass); habit and spikes. USA. Copyright Public Domain/released by USDA-NRCS PLANTS Database/Cassondra Skinner	Habit and spikes	Agropyron cristatum (crested wheatgrass); habit and spikes. USA.	Public Domain/released by USDA-NRCS PLANTS Database/Cassondra Skinner
Title Spike Caption Agropyron cristatum (crested wheatgrass); single spike. USA. Copyright Public Domain/released by USDA-NRCS PLANTS Database/Cassondra Skinner	Spike	Agropyron cristatum (crested wheatgrass); single spike. USA.	Public Domain/released by USDA-NRCS PLANTS Database/Cassondra Skinner
Title Habit Caption Agropyron cristatum (crested wheatgrass); habit, showing drying seed heads. Montana, USA. August, 2009. Much of what passes as Montana steppe (prairie) actually comprises mostly few grass species that withstand long histories of overstocking, such as Agropyron cristatum (crested wheatgrass), Agropyron dasystachyum (thickspike wheatgrass), and Stipa comata (needle and thread grass). Copyright ©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0	Habit	Agropyron cristatum (crested wheatgrass); habit, showing drying seed heads. Montana, USA. August, 2009. Much of what passes as Montana steppe (prairie) actually comprises mostly few grass species that withstand long histories of overstocking, such as Agropyron cristatum (crested wheatgrass), Agropyron dasystachyum (thickspike wheatgrass), and Stipa comata (needle and thread grass).	©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Title Spikes Caption Agropyron cristatum (crested wheatgrass); habit. The flowering head or spikes are distinctive in bearing widely diverging spikelets, separated by short internodes. Montana, USA. August, 2009. Copyright ©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0	Spikes	Agropyron cristatum (crested wheatgrass); habit. The flowering head or spikes are distinctive in bearing widely diverging spikelets, separated by short internodes. Montana, USA. August, 2009.	©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Title Habit Caption Agropyron cristatum (crested wheatgrass); habit. Close view of the flowering head and spikes, which are distinctive in bearing widely diverging spikelets, separated by short internodes. Montana, USA. August, 2009. Copyright ©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0	Habit	Agropyron cristatum (crested wheatgrass); habit. Close view of the flowering head and spikes, which are distinctive in bearing widely diverging spikelets, separated by short internodes. Montana, USA. August, 2009.	©Prof Matt Lavin-2009/Bozeman, Montana, USA - CC BY-SA 2.0
Title Seeds Caption Agropyron cristatum (crested wheatgrass); seeds. USA. Copyright Public Domain - released by the USDA-NRCS PLANTS Database/Steve Hurst	Seeds	Agropyron cristatum (crested wheatgrass); seeds. USA.	Public Domain - released by the USDA-NRCS PLANTS Database/Steve Hurst

Identity

Preferred Scientific Name

• Agropyron cristatum (L.) Gaertn.

Preferred Common Name

• crested wheatgrass

Other Scientific Names

• Agropyron barginensis Skvortsov
• Agropyron brandzae Pantu & Solacolu
• Agropyron cristatiforme P.K.Sarkar
• Agropyron cristatum Besser
• Agropyron czerepanovii Tzvelev
• Agropyron dagnae Grossh.
• Agropyron distichum (Georgi) Peschkova
• Agropyron erickssonii (Melderis) Peschkova
• Agropyron hirsutum Ledeb.
• Agropyron imbricatum Roem. & Schult.
• Agropyron incanum (Nábelek) Tzvelev
• Agropyron karadaghense Kotov
• Agropyron karataviense Pavlov
• Agropyron kazachstanicum (Tzvelev) Peschkova
• Agropyron lavrenkoanum Prokudin
• Agropyron litvinovii Prokudin
• Agropyron muricatum (Link) Schult.
• Agropyron pachyrhizum A.Camus
• Agropyron pectinatum (M.Bieb.) P.Beauv.
• Agropyron pinifolium Nevski
• Agropyron ponticum Nevski
• Agropyron puberulum (Boiss. ex Steud.) Grossh.
• Agropyron pumilum (L.f.) P.Beauv.
• Agropyron sclerophyllum (Novopokr.) Novopokr.
• Agropyron stepposum Dubovik
• Agropyron tarbagataicum Plotn.
• Avena cristata (L.) Roem. & Schult.
• Brachypodium brachystachyum Voss
• Bromus cristatus L.
• Costia cristata (L.) Willk.
• Costia imbricata (Roem. & Schult.) Willk.
• Cremopyrum pectinatum (M.Bieb.) Schur
• Elymus pectinatus (M.Bieb.) Laínz
• Eremopyrum cristatum (L.) Willk. & Lange
• Eremopyrum puberulum (Boiss. ex Steud.) Grossh. ex Prokudin
• Festuca pectiniformis (Roem. & Schult.) A. V. Bukhteeva
• Kratzmannia cristata (L.) Skalicky & V.Jirasek
• Kratzmannia imbricata (Roem. & Schult.) Opiz
• Kratzmannia pectinata (M.Bieb.) Skalicky & V.Jirasek
• Secale pumilum (L.f.) Pers.
• Triticum caucasicum Spreng.
• Triticum cristatum (L.) Schreb.
• Triticum hirsutum Hornem.
• Triticum imbricatum M.Bieb.
• Triticum intermedium M.Bieb. ex Kunth
• Triticum muricatum Link
• Triticum pectinatum M.Bieb.
• Triticum pectiniforme Steud.
• Triticum puberulum Boiss. ex Steud.
• Triticum pumilum L.f.
• Zeia cristata (L.) Lunell

International Common Names

• English: crested wheat grass; fairway crested wheatgrass; fairway wheatgrass
• Spanish: agropiro crestado; agropiro de crista; triguillo crestado
• French: agropyre à crête; agropyron accrêté; chiendent à crête; chiendent pectiné
• Russian: zhitnyak grebenchatyi
• Chinese: bing cao

Local Common Names

• Czech Republic: pýr hrebenitý
• Denmark: kamkvik
• Finland: harjasvehnää
• Germany: Kammquecke
• Greece: agropiron to lofodes
• Hungary: taréjos búzafü
• Italy: agropiro crestato; gramigna crestata
• Japan: kuresuteddo hoiito gurasu
• Poland: perzyk grzebieniasty
• Sweden: kamvete
• Turkey: otlak ayrigi

EPPO code

• AGRCR (Agropyron cristatum)

Summary of Invasiveness

Agropyron cristatum is a long-lived perennial grass that grows in a variety of habitats. Thanks to a combination of a deep fibrous root system and high tolerance of frost, drought, grazing and fire, as well as its ability to produce large amounts of viable seed, this species produces almost monotypic stands, thereby outcompeting native vegetation. Originating in the Russian and Siberian steppes, A. cristatum was first introduced to the North American prairies at the beginning of the 20th century to reseed abandoned cropland, from where it has invaded vast areas of rangeland across the upper USA and southern Canada. Its ecological success has been such that millions of hectares of rangeland, some estimates being as high as 10 million ha, are now occupied by this weed in North America. Some of these A. cristatum communities have remained virtual monocultures for more than 50 years with no apparent successional trends. It is now considered a noxious weed in most parts of the world where it has been introduced and is considered as an invasive particularly in the USA and Canada.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Monocotyledonae
•                     Order: Cyperales
•                         Family: Poaceae
•                             Genus: Agropyron
•                                 Species: Agropyron cristatum

Notes on Taxonomy and Nomenclature

The genus Agropyron in The Plant List (2013) includes 194 scientific plant names of species rank, of which only 26 are accepted species names. Also included are a further 163 scientific plant names of infraspecific rank. For A. cristatum, there are 122 synonyms and one unresolved name (Agropyron czerepanovii Tzvelev).

The genus owes its name to the Greek words agros (field, country) and pyron (grain of wheat) (Charters, 2015), referring to the resemblance of Agropyron plants to cultivated annual wheat (Watson and Dallwitz, 2015). Members of the genus are distributed throughout the temperate regions of the world (Watson and Dallwitz, 2015) and they frequently hybridize with each other, often producing fertile crosses (Dewey, 1983). A. cristatum readily crosses with A. desertorum to produce fertile hybrids (Zlatnik, 1999). In the past, these two have been considered a single species (Zlatnik, 1999). However, APG-III currently recognizes them as separate species (The Plant List, 2013).

A. cristatum was first described by Linnaeus as Triticum cristatum, and originally published as such by Schreber in 1770. The combination of cristatum with Agropyron by Gaertner was published in the same year (Gaertner, 1770). The Latin epithet cristatum means “crested”, alluding to this species’ crest-like inflorescence (Johnson and Smith, 1972).

Description

A. cristatum is a perennial caespitose plant with a fibrous and finely branched root system, with most roots extending to a depth of 1 m. Culms decumbent, 20-70 cm long. Leaf-sheath oral hairs lacking. Leaf-sheath auricles falcate. Ligule an eciliate membrane, 2 mm long. Leaves are abundant, both at the base and along the stems. Leaf-blades involute, 6-12 cm long and 1.5-3 mm wide; stiff. The inflorescence may be lax or dense and is composed of racemes. Racemes single, oblong, bilateral, 1-5 cm long, 10-20 mm wide. Rachis pilose on the surface. The species has a dense spikelet, with a conspicuously flattened head. Spikelet packing broadside to rachis. Rachis internodes oblong. Spikelets pectinate; solitary. Fertile spikelets sessile, comprising 3-8 fertile florets, with diminished florets at the apex. Spikelets oblong, laterally compressed, compressed strongly, 8-15 mm long, breaking up at maturity and disarticulating below each fertile floret. Glumes persistent, shorter than spikelet, firmer than fertile lemma. Lower glume ovate, 3-5 mm long, 1.0 length of upper glume; coriaceous, 1-keeled, keeled all along, 3 -veined. Lower glume surface glabrous or pilose. Lower glume apex acuminate, awned, 1 -awned. Lower glume awn 1-2 mm long. Upper glume ovate, 3-5 mm long, 0.66 length of adjacent fertile lemma; coriaceous, 1-keeled, keeled all along, 3 -veined. Upper glume lateral veins convergent at apex. Upper glume surface glabrous or pilose. Upper glume apex acuminate, awned, 1 -awned. Upper glume awn 1-2 mm long. Fertile lemma elliptic, 5-7 mm long, chartaceous, keeled, keeled above; 5 -veined. Lemma surface pilose. Lemma apex acuminate, awned, 1 -awned. Principal lemma awn 3-4 mm long overall; limb scabrous. Palea keels scabrous. Apical sterile florets resembling fertile though underdeveloped. Ovary with a fleshy appendage below style insertion; pubescent on apex. Caryopsis with adherent pericarp, oblong, sulcate on hilar side, hairy at apex, apex fleshy. Embryo 0.2 times the length of caryopsis. Hilum linear, 1.0 length of caryopsis. Disseminule comprising a floret (from Clayton et al., 2015).

Plant Type

Distribution

A. cristatum is a native of Eurasia, found over a wide area encompassing the Altai Mountains, central Siberia, Yakutia and the Far East in Russia, as well as Mongolia and northeast China (AgroAtlas, 2015). The Flora of China also has it listed as native to Japan, Korea, Pakistan, southwest Asia and Europe (Flora of China Editorial Committee, 2015). It has been introduced and become naturalized in other Nearctic and steppe-like habitats worldwide, including in Australasia, North and South America and northern Africa. In North America it has been planted from Alaska south to California, throughout western Canada, east in the USA to Ohio and south to Texas. The species is most common in the northern Great Plains, especially North and South Dakota, eastern Montana and Wyoming, and in southern Saskatchewan and southeastern Alberta. The grass is used throughout the arid and semi-arid regions of the North American West (Shiflet, 1994).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

A. cristatum was intentionally introduced by the US Department of Agriculture from Russia and Siberia, according to Zlatnik (1999) in 1906. However, Davison and Smith (1996) state that introduction to the USA occurred in 1898 as part of a governmental programme to identify valuable plants for introduction to the country. According to Dillman (1946), A. cristatum was first successfully established in the USA between 1907 and 1913. It became prevalent in the 1930s when it was used to seed abandoned cropland (Zlatnik, 1999).

Its ecological success has been such that it is estimated that between 5 and 26 million acres (2 to 10 million ha) of rangeland are now occupied by this weed in North America (Lesica and DeLuca, 1996; Pellant and Lysne, 2005; Grant-Hoffman et al., 2012). According to Asay et al. (1999), some of these A. cristatum communities have remained virtual monocultures for more than 50 years without apparent successional trends. It is now considered a weed in most parts of the world where it occurs (Global Compendium of Weeds, 2015), and is listed as an invasive plant by the USDA Forest Service (2015).

Introductions

Habitat

A. cristatum is a plant of steppes and steppe-like habitats such as dry rangelands. In its native range it is frequently found on carbonate slopes in the forest steppe belt, on dry and inundated terraces, and in steppe woodlands (AgroAtlas, 2015). According to Hannaway and Larson (2004), A. cristatum is most successful in areas with 230-380 mm of rainfall, except in more southern locations where 300-380 mm are required. A. cristatum is adapted to altitudes between 1500 and 2800 m (FAO, 2007). 

Habitat List

Hosts/Species Affected

According to Vaness and Wilson (2007), A. cristatum has an advantage over native C3 grasses such as Stipa comata and Pascopyrum smithii [Elymus smithii]. Moreover, this species outcompetes other grasses such as Agropyron spicatum [Elymus spicatus] through seed production.

Growth Stages

Biology and Ecology

Genetics

Agropyron taxa have a chromosome base number of x = 7 and occur as diploids, tetraploids or hexaploids. Their haplomic genome constitution is P (Watson and Dallwitz, 2015). A. cristatum individuals have 2n = 14, 28 or 42 chromosomes (Dewey and Asay, 1982).

Reproductive Biology

Anthesis occurs from June to August. Pollination, as in other grasses, is primarily by wind. A. cristatum is in general cross-pollinated but is not completely self-sterile. Cross pollination results in wide variability within the species in plant type and in vegetative and floral characteristics (Hannaway and Larson, 2004). Propagation is primarily by seed (Ogle, 2006).

Physiology and Phenology

A. cristatum is a perennial grass possessing a C3 photosynthetic pathway (Watson and Dallwitz, 2015). In North America, it produces leaves in the spring about 10 days after Poa spp. and about two weeks earlier than native wheatgrasses, and shows good spring growth (Ogle, 2006). It then goes dormant in the summer, but if soil moisture is available it will grow again in the autumn (Zlatnik, 1999).

Longevity

A. cristatum is a long-lived perennial. According to the FAO (2007), productive stands can be up to 20-35 years old.

Population Size and Structure

Once established, A. cristatum quickly dominates the seedbank (Marlette and Anderson, 1986), thereby hindering the growth of native species (Henderson and Naeth, 2005) and forming nearly monotypic stands (Fansler and Mangold, 2010). A study performed by Heidinga and Wilson (2002) found that where A. cristatum occurred on sites with different degrees of disturbance it produced twice as many seeds as all other species combined.

Associations

A. cristatum has been planted throughout North America and is known to occur in a large number of plant community associations. It has been recorded as present in at least 12 ecosystems (including woodlands, sagebrush, savanna, shrub steppe, prairie and grasslands), 15 SAF cover types and 85 SRM rangeland cover types (Encyclopedia of Life, 2015). In the Great Basin in Nevada, for example, when sown it thrived in mesic communities with big sagebrush (Artemisia tridentata), basin wildrye (Elymus cinereus [Leymus cinereus]), Sandburg bluegrass (Poa secunda), Columbia needlegrass (Achnatherum nelsonii subsp. dorei [Stipa nelsonii]) and slender wheatgrass (Elymus trachycaulus) (Eckert et al., 1961).

Agropyron taxa, including A. cristatum, are particularly susceptible hosts of Puccinia striiformis, a virulent rust pathogenic on wheat and barley (Roelfs and Bushnell, 2014).

Environmental Requirements

According to the Encyclopedia of Life (2015), the species prefers well-drained, deep, loamy soils of fine, medium or moderately coarse texture, from sandy loams to clay loams. It does not grow well in loose sandy soils or heavy clays, preferring moderately alkaline conditions with low to medium fertility. Although it does not grow well on saline soils, it can tolerate salinity in the range 5-15 mS/cm. A. cristatum is extremely drought tolerant and does not tolerate prolonged flooding. It tolerates shade but grows best in open conditions.

Climate

Air Temperature

Rainfall

Rainfall Regime

Soil Tolerances

Soil drainage

• free

Soil reaction

• alkaline
• neutral

Soil texture

• heavy
• light
• medium

Special soil tolerances

• infertile

Natural enemies

Notes on Natural Enemies

A. cristatum is a major host of the black grass bug (Labops hesperius), a common predator of grass stands. Other insect pests are leafhoppers (Cicadellidae), grubs (Scarabaeoidea), click beetles (Elateridae) and snout weevils (Curculionidae) (Hannaway and Larson, 2004).

In laboratory trials, volatile substances and aqueous extracts from the leaves of Artemisia tridentata exhibited allelopathic, inhibitory effects on germination and shoot and radicle growth of A. cristatum seedlings (Groves and Anderson, 1981).

Means of Movement and Dispersal

Natural Dispersal

Propagules of A. cristatum are wind dispersed (Marlette and Anderson, 1986).

Vector Transmission (Biotic)

In North America, the rodent Peromyscus maniculatus disperses the seeds of A. cristatum (Miller, 2010), while in Mongolia it was shown that seed attachment to the wool of sheep allowed for long distance dispersal by flocks (up to 15 km a day), with seeds remaining attached for hours and even days (Bläss et al., 2010).

Intentional Introduction

This species is intentionally introduced for agricultural or erosion-control purposes.

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

As a susceptible host of the pathogen Puccinia striiformis, it can act as a reservoir for infection, causing economic losses in cereal crops (Roelfs and Bushnell, 2014).

Environmental Impact

Impact on Habitats

It has been proven that by displacing native vegetation, A. cristatum alters rangeland soil chemical properties, reducing soil organic matter and increasing nitrate nitrogen and phosphorus contents, as well as soil chemical index and urease activity (Dormaar et al., 1995). Christian and Wilson (1999) found that in abandoned fields sown to A. cristatum the soil had significantly less available N, total nitrogen and total carbon than soils under successional prairie. Moreover, in areas dominated by A. cristatum, there is an increase in bare ground compared to native mixed grass prairie (Sutter and Brigham, 1998).

Impact on Biodiversity

Outside of its native range, A. cristatum has been identified as a driver for the loss of biodiversity in natural grasslands (Henderson and Naeth, 2010). For example, where sown in abandoned fields in the Great Plains, there were fewer native species than in the prairie, resulting in significantly lower species richness and diversity (Christian and Wilson, 1999). Working with historical data from western Colorado, Grant-Hoffman et al. (2012) found that after planting public lands to crested wheatgrass, the species increased in frequency significantly over time; however, of the other plant species present, only Elymus elymoides and Sporobolus cryptandrus decreased in frequency with increasing crested wheatgrass cover. Five species of grass, two shrubs and one forb were able to persist to various degrees.

The Goose Creek milkvetch (Astragalus anserinus), a low-growing, matted, perennial native forb, listed in the USA as a candidate species under the Endangered Species Act, grows only in a limited area of the Goose Watershed of the Upper Snake River Basin in Idaho, Nevada and Utah. Existing populations are threatened by wildfires, livestock trampling, rights of way and invasive non-native species. The non-native species of most concern to Goose Creek milkvetch are cheatgrass (Bromus tectorum), because of its tendency to increase the frequency of wildfires, and leafy spurge (Euphorbia esula) and crested wheatgrass, because of their ability to competitively displace the slower growing native, especially after disturbance events such as wildfires (US Fish and Wildlife Service, 2014). 

According to Reynolds and Trost (1980), areas where A. cristatum is cultivated can be less favourable not only for native plants, but also for birds and wildlife. The abundance and diversity of songbirds in Saskatchewan was thought to be reduced when mixed grass prairie was converted to more open crested wheatgrass habitat (Sutter and Brigham, 1998).

Threatened Species

Social Impact

Planting of A. cristatum in large blocks within native rangelands is seen as reducing the aesthetic value of the rangeland landscape (Davison and Smith, 1996).

Risk and Impact Factors

• Proved invasive outside its native range
• Has a broad native range
• Abundant in its native range
• Highly adaptable to different environments
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Tolerant of shade
• Benefits from human association (i.e. it is a human commensal)
• Long lived
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year

• Ecosystem change/ habitat alteration
• Modification of fire regime
• Modification of nutrient regime
• Modification of successional patterns
• Monoculture formation
• Negatively impacts agriculture
• Reduced amenity values
• Reduced native biodiversity
• Threat to/ loss of native species

• Competition - monopolizing resources
• Competition - shading
• Pest and disease transmission
• Hybridization
• Interaction with other invasive species
• Rapid growth

• Highly likely to be transported internationally deliberately
• Difficult to identify/detect as a commodity contaminant

Uses

Economic Value

As a fodder species, A. cristatum has high yields and is palatable to all classes of livestock and wildlife, and supplies green forage in both spring and autumn (Johnson, 1986; Mayland, 1986). Its seeds are easy to collect and sow with standard equipment, which is particularly important because cultivation can be carried out at an economically reasonable price (Johnson, 1986).This species is also a tertiary genetic relative of wheat (based on hybrid formation with Triticum aestivum) and is viewed as a genetic resource for wheat breeding (Limin and Fowler, 1990).

Social Benefit

According to Hannaway and Larson (2004) and Ogle (2006), various low-growing, rhizomatous strains of A. cristatum are used in lawns and turfs. Moreover, the species can be used in urban areas where irrigation water is limited to provide ground cover, weed control and to stabilize ditch banks, dikes, pipelines, power lines and roadsides (Ogle, 2006).

Environmental Services

A. cristatum has been used extensively for erosion control (Brown et al., 1985), as well as to revegetate burned and degraded land (Zlatnik, 1999). It is also a fire-retardant species that can help control wildfires in semi-arid rangelands (Green, 1977). In spite of its detrimental effects, one reason A. cristatum continues to be used in the USA is its ability to outcompete other more detrimental invasive plants such as cheatgrass (Bromus tectorum) (Francis and Pyke, 1996).

Moreover, A. cristatum is an important source of food for mule deer (Odocoileus hemionus) and pronghorn antelope (Antilocapra americana), particularly at times when other preferred food sources are unavailable (Urness, 1986). Crested wheatgrass is highly palatable to and good cover for black-tailed jackrabbits (Lepus californicus) (Ganskopp et al., 1993) as well as deer mice (Peromyscus spp.), montane voles (Microtus montanus), Ord's kangaroo rats (Dipodomys ordii) and Townsend's ground squirrels (Urocitellus townsendii) (Koehler and Anderson, 1991).

Uses List

Animal feed, fodder, forage

• Fodder/animal feed
• Forage

Environmental

• Erosion control or dune stabilization
• Firebreak
• Revegetation

Genetic importance

• Gene source

Ornamental

• garden plant

Similarities to Other Species/Conditions

Dewey (1986) observed that Agropyron taxa introduced into North America easily lose their taxonomic identity and genetic integrity because of extensive intercrossing and their identification is often difficult and unsatisfactory. In North America, particularly, A. cristatum, A. fragile (Siberian wheatgrass) and A. desertorum (desert wheatgrass) are easily confused. A. cristatum has short-broad spikes that taper at the top, smaller seeds, grows shorter, and has finer leaves and stems than A. desertorum, which has longer spikes that vary in shape from comb-like to oblong. Compared to the other two species, A. fragile has finer leaves and stems, narrower and awnless glumes and lemmas, and the spikelets are more ascending, which gives the spike a narrow, oblong, sub-cylindrical shape. It is also more drought tolerant and retains its greenness later into the summer than either A. cristatum or A. desertorum (Ogle, 2006).

Prevention and Control

Physical/Mechanical Control

Attempts to control A. cristatum with mechanical treatments (i.e., removal of vegetation with the use of a dixie harrow pulled behind a tractor) and seeding have yielded mixed results. In their study, Hulet et al. (2010) found that mechanical treatments reduced the cover of A. cristatum. In contrast, Grant-Hoffman et al. (2012) found that in mechanically treated areas, the only significant trend was a reduction of native grasses, indicating that in areas planted with A. cristatum the frequency of this species will increase over time.

Fire can be a double-edged sword for the control of A. cristatum: depending on the season when it takes place, a fire event can reduce crested wheatgrass stands or exacerbate their regeneration and further spread. Because A. cristatum burns quickly there is usually little heat transfer into the soil, thus the root system tends to remain undamaged, allowing more rapid post-fire recovery than in native bunchgrasses (Skinner and Wakimoto, 1989). In spite of this, Bradley et al. (1992) found that spring fire can decrease yields of A. cristatum for several years.

Chemical Control

A study by Schultz and Creech (2013) on the effects of six herbicides on sown crested wheatgrass seedlings found that sulfometuron had the most adverse effect on seedling density and vigour, while sulfosulfuron had few if any adverse effects. Hirsch et al. (2012) observed that seedling emergence in A. cristatum was significantly reduced by pre-emergence application of rimsulfuron, particularly on sagebrush shrubland soil.

Monitoring and Surveillance (Incl. Remote Sensing)

In their study of northern mixed grass prairie in Canada, Zhou and Guo (2007) used SPOT-5 imagery to detect invasive A. cristatum. For this purpose, they employed an artificial neural network classifier based on a back propagation algorithm to classify A. cristatum and native vegetation. The results indicated that the use of a new vegetation index (ExpNDMI) derived from NDMI (normalized difference moisture index) could significantly increase the spectral separability between A. cristatum and native grasslands and improve classification accuracy. Further, the results of their work suggest that a single-date SPOT-5 image with 10 m resolution would be useful in discriminating A. cristatum from native species in mixed grasslands.

Ecosystem Restoration

A field experiment by Bakker and Wilson (2004) conducted in the northern Great Plains of North America examined the potential of ecological restoration to constrain invasion of an old field by A. cristatum. Between 1994 and 1996 they seeded 140 restored plots with a mixture of C3 and C4 native grass seed, and left unrestored plots unplanted. Monitoring of vegetation in the plots periodically between 1994 and 2002 showed an increasing presence of A. cristatum (both in terms of occurrence and cover) over this period. However, A. cristatum invaded one-third fewer restored than unrestored plots, suggesting that restoration constrained invasion. Further, A. cristatum cover in restored plots decreased with increasing planted grass cover. Evidence suggested that A. cristatum cover was more strongly correlated with planted grass cover than with distance from the A. cristatum source, species richness, percentage bare ground or percentage litter. Overall, the results suggested that restoration can act as a filter, constraining invasive species while allowing colonization by native species.

References

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Contributors

02/11/2015    Original text by:

Diana Quiroz, Consultant, Netherlands

Distribution Maps