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Aegilops cylindrica Host - Jointed goatgrass

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Cyperales: Poaceae

Identification
Context
Geographical Distribution
Habitat
Field Recognition/Morphology
Biology/Life Cycle
Dispersal
Environmental Impacts
Economical Impacts
Control/Management
Reporting
Figures
Additional Web Links
References

Identification

Name: Aegilops cylindrica Host (1802)

Common names (E): Jointed goatgrass (Darbyshire, 2003), jointed goatgrass, jointgrass, goatgrass (Randall, 2002).

Common names (F): Égilope cylindrique

Jointed goatgrass is a serious winter annual weed in the United States. It was probably introduced into the United States as a contaminant in winter wheat seed. The weed is now considered one of the ten most common weeds of cereals in the United States. In Canada, two small populations of jointed goatgrass have been discovered and are confined near Port Colborne, Ontario, since 2006.

In the CFIA, a Pest Risk Analysis was initiated in 2006 to assess the cost-effectiveness of requiring phytosanitary measures for controlling further introductions of jointed goatgrass in Canada under the authority of the Plant Protection Act. The process still underway.

Jointed goatgrass is regulated under the Seeds Act and Regulations. The Seeds Act provides authority for the testing, inspection, quality and sale of seeds in Canada. This species is listed as a Class 1 Prohibited Noxious Weed Seed under the Weed Seeds Order. Its presence as a contaminant in domestic and imported seed is prohibited (Section 4(2), Seeds Act).

Acts and regulations we enforce include:

Seed Act
- Weed Seed Order, 2005

Geographical Distribution

Native to southeastern Europe and western Asia.

Asia: Afghanistan, Armenia, Azerbaijan, Georgia, Iran, Iraq, Kazakhstan, Kyrgyzstan, Lebanon, Pakistan, Russian Federation (Ciscaucasia, Dagestan); Tajikistan, Turkey, Turkmenistan, Uzbekistan (USDA, ARS, 2006); China (Qinghai, Shaanxi and Hebei provinces) (Flora of China online, 2002).

Europe: Naturalized in Europe (Tutin et al., 1980; USDA, ARS, 2006).

North America:

Mexico: Chihuahua province (SAGAR, 1995, cited in NAPPO, 2003);
United States: occurs throughout most of the country (USDA, NRCS, 2006);
Canada: In late May 2006, jointed goatgrass was found near Port Colborne, Ontario, where a population was growing in disturbed ground near an abandoned quarry and decommissioned railway line. Investigations have taken place to learn more about the population and to consider options for eradication (Haber, 2006). A second population was discovered in 2007.

Habitat

In its native range in Asia, jointed goatgrass is typically found on open stony slopes, along roadsides, in fields and plantations of some cultivated crops, sometimes in weedy meadows and steppes, and up to the middle mountain belt (Tsvelev, 1984). In Europe it is reported to be common in fields, wastelands, and dry open areas (Jauzein and Montegut, 1983). In North America, jointed goatgrass occurs throughout the U.S. as a weed in cultivated fields, particularly in winter wheat (Figure 1), as well as in pastures and disturbed areas. In general, jointed goatgrass is a xerophile, preferring dry open habitats (Jauzein and Montegut, 1983). In addition to winter wheat fields, jointed goatgrass has also been found in alfalfa fields and grasslands in Wyoming, along roadsides and fence rows in Texas, and in rangeland around wheat-growing areas (including Conservation lands) in most of the western states (Donald and Ogg, 1991).

The range of jointed goatgrass in the U.S. extends up to approximately USDA Plant Hardiness Zone 3b (USDA Plant Hardiness Zone Map, 1990; USDA, NRCS, 2006).

Field Recognition / Morphology

Jointed goatgrass is a winter annual grass that is very similar in appearance to winter wheat (Wicks et al., 2004). Plants consist of up to 50 erect flowering stalks (Donald and Ogg, 1991) (Figure 2 and 3). The root system of jointed goatgrass is shallow and fibrous (Donald and Ogg, 1991). Stems are numerous, erect, 40 to 60 cm tall, and branching at the base (Hitchcock, 1950). Leaves are alternate and 2 to 5 mm wide (Barkworth, 2006). Leaf length varies from 3 to 15 cm. Leaves are glabrous or sparsely hairy (Tutin et al.,1980), and hairs are evenly spaced along the leaf blade margin (NJGRP, 2006) (Figure 4). Auricles where the leaf sheaf meets the blade are hairy (Hitchcock, 1950). The seedhead, or spike, is a narrow cylinder 5-10 (18) cm long with alternately arranged spikelets on opposite sides of the rachis (main axis of the spike) (Figure 5, 6 and 7). Spikelets are 8-10 mm long and contain 2-4 (5) florets each (Figure 7, 8 and 9). Glumes on the lower spikelets are awnless, or have one awn (0.2-0.5 cm). Glumes of apical spikelets have long awns (3-9 cm) (Figure 5). Each spikelet contains an average of 2 seeds (Hitchcock, 1950; Donald and Ogg, 1991; Barkworth, 2006). Seeds are reddish-brown caryopses, 6.5-9 mm long, 2 mm wide, and grooved (Figure 10). Jointed goatgrass plants produce an average of 130 seeds, and up to 3000 seeds under optimal conditions (Donald and Ogg, 1991).

	Jointed goatgrass	Winter and Spring Wheat
Seedlings	Thinner, first leaf reddish to brownish green (Donald and Ogg, 1991) (Figure 11).	First leaf whitish green (Donald and Ogg, 1991).
Leaf blades	Shorter (Donald and Ogg, 1991)	Longer (Donald and Ogg, 1991)
Leaf margin	Evenly spaced hairs near the base (NJGRP, 2006) (Figure 4)	Few or no hairs (NJGRP, 2006)
Ligule	0.2 - 0.8 mm	0.6 - 2.0 mm
Leaf midrib of the leaf blade	Inconspicuous (S. Darbyshire, 2006, pers. comm.)	Conspicuous (S. Darbyshire, 2006, pers. comm.)
Spikes	Narrower and cylindrical (Donald and Ogg, 1991) (Figure 12)	Wider (Donald and Ogg, 1991)

Biology / Life Cycle

In general, the jointed goatgrass life cycle mirrors that of winter wheat (Donald and Ogg, 1991).

Jointed goatgrass germinates in the fall. Jointed goatgrass can emerge from the same seed depths as winter wheat. Highest emergence rates occur from shallow depths of 0 to 5 cm (Morrow et al., 1982). Jointed goatgrass is a facultative selfer and requires a period of vernalization [chilling] to initiate seed production (Fandrich and Mallory-Smith, 2006). Jointed goatgrass and winter wheat seedlings remain in a dormant state during the winter months (Donald and Ogg, 1991). In spring, as temperatures rise, both species resume growth and switch to a reproductive phase (CFIA, 1999; Fandrich and Mallory-Smith, 2006).

Seed maturation in jointed goatgrass generally occurs at the same time as winter wheat or slightly before (Donald and Ogg, 1991). In Canada, winter wheat is usually harvested in late July or in August, depending on when its thermal requirements are met (Fowler, 2002; Ontario Wheat Board, 2006). Jointed goatgrass seedheads are often cut during combine harvesting or may shatter and fall to the soil surface (Donald and Ogg, 1991).

Jointed goatgrass seed can persist in the soil for 3 to 5 years. Factors that affect persistence include burial location and depth, climatic conditions, and the amount of seed going back into the seed bank (White, 2002).

The genus Aegilops is capable of hybridizing with other species in this genus, with many species of Triticum, and with Secale (S. Darbyshire, 2006, pers. comm.). Wheat and jointed goatgrass can hybridize and produce fertile offspring, although fertility rates are low (Stone and Peeper, 2004) (Figure 12).

Dispersal

The primary means of dispersal of jointed goatgrass seed is as a contaminant in winter wheat seed (Donald and Ogg, 1991) (Figure 9). Spillage of contaminated grain from rail cars is another potential means of dispersing jointed goatgrass (Haber, 2006). Custom machinery is sometimes used to harvest winter wheat, and this has been thought to spread jointed goatgrass within the U.S. Custom combine harvesters typically follow the winter wheat harvest northward. This practice also occurs across the Canada/U.S. border, and is a potential mechanism of jointed goatgrass movement from the U.S. into Canada. In a similar way, farm trucks used for multiple purposes, such as hauling bulk wheat seed, fertilizer and harvested grain are a potential means of dispersal for jointed goatgrass. Therefore, cleaning trucks between uses is an important management practice to prevent the spread of weeds (Wicks et al., 2004).

Straw is another potential pathway for jointed goatgrass. Straw originating from the U.S. and used for livestock bedding or packing material could contain seeds of jointed goatgrass (S. Darbyshire, 2006, pers. comm.).

Contaminated wheat may be fed to livestock. High seed viability and seedling emergence can be expected from jointed goatgrass seed after passage through cattle (Lyon et al., 1992). Thus, cattle or other livestock fed contaminated wheat may act as yet another mechanism to disperse jointed goatgrass seed. Similarly, dispersal of jointed goatgrass seed by birds and mammals other than livestock is also possible.

Jointed goatgrass joints can also be dispersed from runoff water, since they float (Donald and Ogg, 1991).

Environmental Impacts

Jointed goatgrass has the potential to have indirect impacts on the environment, such as contributing to grower decisions to cultivate winter wheat less frequently. Winter wheat is a relatively environmentally friendly crop because it is well suited to reduced tillage management systems (Dunn and Fleury, 1998; Fowler, 2002) and it provides waterfowl habitat (Ducks Unlimited, 2005).

Economical Impacts

In the U.S., jointed goatgrass infests more than 5 million acres of winter wheat and 2.5 million acres of fallow land: losses in winter wheat crop yield and quality due to jointed goatgrass are estimated at $150 million annually (Mallory-Smith, 2001). Yield reductions are dependent on a variety of factors, notably rainfall, soil moisture and the severity of previous infestations. This weed can also cause dockage losses in wheat. In non-herbicide resistant winter wheat varieties, costs of controlling jointed goatgrass are mostly indirect due to lack of selective control options.

Because of its similarity to wheat, jointed goatgrass is very difficult to control and could become a serious problem for wheat producers in Canada if it spreads northwards across the border. Wheat has been one of the major crops in Canada for at least the last 75 years, and is grown across the country, with a concentration in the Prairie provinces. Spring wheat comprises the bulk of production, with approximately 23 million tonnes (Mt) produced annually (AAFC, 2004). Total annual production of winter wheat is typically between 1.5 and 2 Mt (AAFC, 1999) grown primarily in southwestern Ontario and parts of the Prairies, with limited production elsewhere (AAFC, 2004). An estimated 10% of Ontario wheat producers plant winter wheat once every two or three crops.

Control / Management

The management of jointed goatgrass in winter wheat requires a systems approach that integrates several control mechanisms into a multi-year management plan. When the eradication is the final objective, it must be kept in mind that a single plant is able to produce seeds, which will feed the seed bank and reintroduce the plant for several years. Control methods include:

Prevention (from Donald and Ogg, 1991; NAPPO, 2003):

Using certified seed
Covering transport trucks loaded with contaminated grain
Cleaning jointed goatgrass seed from contaminated farm machinery,trucks and rail cars
Processing contaminated feed before feeding livestock
Not baling/transporting contaminated straw
Using special length-graders and gravity-tables to separate jointed goatgrass seed from wheat seed
Mowing field margins, roadsides, etc. that are contaminated with jointed goatgrass prior to seed set

Cultural / Mechanical: It is recommended that winter small-grain crops be grown only once in a three- to four-year rotation (Evans et al., 1999). At this frequency, jointed goatgrass may still persist at a lower rate of infestation (Lyon and Baltensperger, 1995). Several studies in the U.S. have shown that taller winter wheat varieties are able to better compete with jointed goatgrass than are shorter varieties (Evans et al., 1999; Westra, 1999). Studies conducted in Washington State found that delaying the wheat planting date can sometimes have a positive impact on jointed goatgrass management, if an early flush of the weed occurs and can be controlled with a non-selective herbicide or tillage (Westra, 1999). These studies also showed that increasing the wheat seeding rate and reducing the width of wheat rows had positive impacts on jointed goatgrass control (NAPPO, 2003).

Chemical: Non-selective herbicides such as glyphosate can control jointed goatgrass not only when applied in fallow fields, but in subsequent years on tolerant crops, e.g. glyphosate tolerant canola. Selective herbicides to control jointed goatgrass are available in the U.S. for use in other crops, but none are currently available for use in winter wheat (Wicks et al., 2004).

Biological: No specific agents are currently approved for biological control of jointed goatgrass in the U.S. (ODA, 2006).

Reporting

Reporting the jointed goatgrass in Canada should be done through your local CFIA office. For a list of offices, please call 1-800-442-2342 or consult the list of regional offices online.