Aegilops cylindrica
Encyclopedia
Aegilops cylindrica, also known as jointed goatgrass. is an annual grass seed that is part of the tribe Triticeae
, along with wheat
and some other cereal
s . It is not native to the United States, however it has become a serious issue as a weed since it was introduced in the late 19th century . Due to its relation to winter wheat, it is very difficult to control. Not only are the joints similar in shape and size to the seeds of winter wheat, making it difficult to remove through grain cleaning methods, the shared genetics mean that no registered herbicides are available to single out jointed goatgrass while leaving winter wheat unharmed . This poses problems for farmers who have to suffer through reduced yields and poorer quality winter wheat .
settlers from Russia brought Turkey winter wheat to Kansas . The first sample of jointed goatgrass was collected in Centerville, DE in 1870 and later samples collected in 1910 showed that jointed goatgrass had escaped from experimental plots on South Dakota State University campus at Brookings, SD .
In 1999, it was reported that jointed goatgrass had infested an estimated 2 million hectares in the US alone, and that this was annually increasing at a rate of about 20 000 hectares . In 1986, jointed goatgrass had been reported as having infected less than 1% of winter wheat fields in seven counties in Nebraska, yet it was rated one of the ten most troublesome weeds, concerning 13% of respondents to a 1984 farmer survey .
Human activities, wind, and machinery help to spread jointed goatgrass seeds once the joints disarticulate . However, due to the size of joints, wind dispersal is not as effective at spreading jointed goatgrass . Some of the human activities that helped spread jointed goatgrass include; planting contaminated wheat, allowing joints to blow from passing trucks hauling grain, transporting combines to different fields, or using straw spreaders on combines . Steven Miller argued that some states did not have laws that prevented contaminated winter wheat from being certified, which helped lead to it still being planted . Combines with straw spreaders are likely to spread jointed goatgrass joints farther than combines without these spreaders . Also, because the joints can float, runoff
from fields can take them into rivers where they can aggregate and create an infestation in moist depressions
, draws in fields, or along drainageways . It has been observed by growers and researchers that jointed goatgrass has a higher germination and emergence rate in compacted soils (such as in the wheel tracts of tractors) than in looser soils .
which allows them to live in cold, continental climates and means they are capable of cross-breeding . They are both C3 plants, have similar phenology
and growth rates and even germinate at the same time . Jointed goatgrass has glabrous to scabrous glumes with upright culms and the ability to produce 50 erect flowering stalks for each isolated plant . Both wheat and jointed goatgrass have spikes
that are sessile
and alternately arranged spikelets on opposite sides of the rachis
. Each spikelet holds one to two seeds, and in some cases three, that are reddish-brown in colour and reach maturity in mid-summer which is when the spikelets shatter . These seeds adhere to the lemma
and palea
of the glume, so that removing the seeds from the joints is difficult .
, leaf spot
, pink mold, foot rot
, dwarf bunt, fron
, root browning, damping off
, and kernel bunt .
When the spikes shatter, the disjointed spikelets are cylindrical in shape and are easily mistaken for small pieces of winter wheat straw . Since the spikelets are similar in shape and size to winter wheat seeds, it is difficult to separate them from the wheat using conventional methods . Better methods use length graders or weight tables, but these are slow and costly to operate . The Official United States Standards for Grain states that when the spikelets get mixed in with the winter wheat, the wheat is considered contaminated and the grade is reduced, resulting in a penalty . The more jointed goatgrass found in the wheat, the lower the grade and the larger the penalty. The lowest penalty is $0.02 per bushel while the highest is $0.15 per bushel .
can be used in winter wheat to improve its tolerance to environmental stresses, diseases and insects . Cattle in parts of the Central Great Plains are able to graze on it as well as winter wheat, and jointed goatgrass can even be ground into feed for other animals .
for up to five years . The best solution is to use several cultural tactics throughout the life cycle
of jointed goatgrass and at a minimum of three different decision times (during the interval between winter wheat crops, before planting winter wheat, after planting but before winter wheat jointing, and before harvesting) . Other cultural practices include burning the residue after harvest and deep moldboard plowing, although Ball et al. point out that these methods can reduce air quality, increase soil erosion, decrease soil productivity and result in lost organic matter
.
Another option for the control of jointed goatgrass is to use deleterious rhizobacteria (DRB) which scientists have already proven can suppress other weeds . However, the success of DRB depends upon its ability to survive which is affected by environmental factors such as soil series
, temperature, moisture, and sunlight exposure . The goal for DRB is for it to be a low-cost, effective method for the control of jointed goatgrass with minimum damage to the environment .
Triticeae
Triticeae is a tribe within the Pooideae subfamily of grasses that includes genera with many domesticated species. Major crop genera are found in this tribe including wheat , barley, and rye; crops in other genera include some for human consumption and others used for animal feed or rangeland...
, along with wheat
Wheat
Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...
and some other cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
s . It is not native to the United States, however it has become a serious issue as a weed since it was introduced in the late 19th century . Due to its relation to winter wheat, it is very difficult to control. Not only are the joints similar in shape and size to the seeds of winter wheat, making it difficult to remove through grain cleaning methods, the shared genetics mean that no registered herbicides are available to single out jointed goatgrass while leaving winter wheat unharmed . This poses problems for farmers who have to suffer through reduced yields and poorer quality winter wheat .
History and Distribution
Jointed goatgrass is a winter annual grass seed native to Southern Europe and Russia , however currently there are at least 23 species distributed worldwide . It is considered a problem weed in United States, where it is now widely spread across western and central regions . It entered the US at several different times and at different locations , however the first was possibly in the late 19th century when MennoniteMennonite
The Mennonites are a group of Christian Anabaptist denominations named after the Frisian Menno Simons , who, through his writings, articulated and thereby formalized the teachings of earlier Swiss founders...
settlers from Russia brought Turkey winter wheat to Kansas . The first sample of jointed goatgrass was collected in Centerville, DE in 1870 and later samples collected in 1910 showed that jointed goatgrass had escaped from experimental plots on South Dakota State University campus at Brookings, SD .
In 1999, it was reported that jointed goatgrass had infested an estimated 2 million hectares in the US alone, and that this was annually increasing at a rate of about 20 000 hectares . In 1986, jointed goatgrass had been reported as having infected less than 1% of winter wheat fields in seven counties in Nebraska, yet it was rated one of the ten most troublesome weeds, concerning 13% of respondents to a 1984 farmer survey .
Human activities, wind, and machinery help to spread jointed goatgrass seeds once the joints disarticulate . However, due to the size of joints, wind dispersal is not as effective at spreading jointed goatgrass . Some of the human activities that helped spread jointed goatgrass include; planting contaminated wheat, allowing joints to blow from passing trucks hauling grain, transporting combines to different fields, or using straw spreaders on combines . Steven Miller argued that some states did not have laws that prevented contaminated winter wheat from being certified, which helped lead to it still being planted . Combines with straw spreaders are likely to spread jointed goatgrass joints farther than combines without these spreaders . Also, because the joints can float, runoff
Runoff
Run-off or runoff may refer to:* Surface runoff, the flow of water, from rain, snow melt, or other sources, over land* Runoff model , a mathematical model describing the rainfall-runoff relations of a rainfall catchment area or watershed...
from fields can take them into rivers where they can aggregate and create an infestation in moist depressions
Depression (geology)
A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.Structural or tectonic related:...
, draws in fields, or along drainageways . It has been observed by growers and researchers that jointed goatgrass has a higher germination and emergence rate in compacted soils (such as in the wheel tracts of tractors) than in looser soils .
Biology
Jointed goatgrass and winter wheat are genetically linked through a D genomeGenome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
which allows them to live in cold, continental climates and means they are capable of cross-breeding . They are both C3 plants, have similar phenology
Phenology
Phenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate...
and growth rates and even germinate at the same time . Jointed goatgrass has glabrous to scabrous glumes with upright culms and the ability to produce 50 erect flowering stalks for each isolated plant . Both wheat and jointed goatgrass have spikes
Spikes
Spikes is the mascot of the Minor League AAA Rochester Red Wings. Spikes is 6 feet tall, and weighs 180 lbs. He was created after the season, the same year in which the Red Wings got their new stadium, Frontier Field.-External links:*...
that are sessile
Sessility (botany)
In botany, sessility is a characteristic of plants whose flowers or leaves are borne directly from the stem or peduncle, and thus lack a petiole or pedicel...
and alternately arranged spikelets on opposite sides of the rachis
Rachis
Rachis is a biological term for a main axis or "shaft".-In zoology:In vertebrates a rachis can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the rachis usually form the supporting axis of the body and is then called the spine or vertebral column...
. Each spikelet holds one to two seeds, and in some cases three, that are reddish-brown in colour and reach maturity in mid-summer which is when the spikelets shatter . These seeds adhere to the lemma
Lemma (botany)
Lemma is a phytomorphological term used in botany referring to a part of the spikelet of grasses . It is the lowermost of two chaff-like bracts enclosing the grass floret. It often bears a long bristle called an awn, and may be similar in form to the glumes - chaffy bracts at the base of each...
and palea
Palea
Palea is a city in Equatorial Guinea. It is located in Annobón Province and has a population of 4433....
of the glume, so that removing the seeds from the joints is difficult .
Agricultural Issues
Jointed goatgrass can reduce the yield of winter wheat by 25 – 50% which can cost farmers up to $145 million . Another problem is that winter wheat provides an overwinter home for winter wheat attacking pests such as Russian wheat aphidRussian wheat aphid
The Russian wheat aphid is an aphid that can cause significant losses in cereal crops. The species was introduced to the United States in 1986 and is considered an invasive species there. This aphid is pale green and up to 2 mm long. Cornicles are very short, rounded, and appear to be lacking...
, leaf spot
Leaf spot
Leaf spots are round blemishes found on the leaves of many species of plants, mostly caused by parasitic fungi or bacteria.A typical spot is "zonal", meaning it has a definite edge and often has a darker border. When lots of spots are present, they can grow together and become a blight or a blotch...
, pink mold, foot rot
Foot rot
Foot rot, or infectious pododermatitis, is a hoof infection commonly found in sheep, goats, and cattle. As the name suggests, it rots away the foot of the animal, more specifically the area between the two toes of the affected animal. It is extremely painful and contagious. It can be treated with...
, dwarf bunt, fron
Fron
Fron is a former municipality in Gudbrandsdal in Oppland, Norway.It was created in 1837 as Fron formannskapsdistrikt, but in 1851 the municipality was split into Nord-Fron and Sør-Fron...
, root browning, damping off
Damping off
Damping off is the term used for a number of different fungus-caused ailments that can kill seeds or seedlings before or after they germinate....
, and kernel bunt .
When the spikes shatter, the disjointed spikelets are cylindrical in shape and are easily mistaken for small pieces of winter wheat straw . Since the spikelets are similar in shape and size to winter wheat seeds, it is difficult to separate them from the wheat using conventional methods . Better methods use length graders or weight tables, but these are slow and costly to operate . The Official United States Standards for Grain states that when the spikelets get mixed in with the winter wheat, the wheat is considered contaminated and the grade is reduced, resulting in a penalty . The more jointed goatgrass found in the wheat, the lower the grade and the larger the penalty. The lowest penalty is $0.02 per bushel while the highest is $0.15 per bushel .
Benefits
Jointed goatgrass does have some benefits in the sense that its germplasmGermplasm
A germplasm is a collection of genetic resources for an organism. For plants, the germplasm may be stored as a seed collection or, for trees, in a nursery.-See also:*Germ plasm, the germ cell determining zone...
can be used in winter wheat to improve its tolerance to environmental stresses, diseases and insects . Cattle in parts of the Central Great Plains are able to graze on it as well as winter wheat, and jointed goatgrass can even be ground into feed for other animals .
Solutions
Since jointed goatgrass and winter wheat are genetically related, there are no registered herbicides that can selectively kill off the jointed goatgrass without harming the winter wheat . However, Newhouse et al. looked at the development of a imidazolinone resistant strain of winter wheat which allows the use of imazamox to kill jointed goatgrass, but Seefeldt et al. mentioned the concerns about the possibility of resistant jointed goatgrass – winter wheat hybrids . This has resulted in a demand for other methods for controlling jointed goatgrass. These include planting only certified winter wheat seed that is free of jointed goatgrass, covering trucks that are transporting contaminated winter wheat, cleaning combines before moving them to a new field, allowing combines to enter each field through one spot only so possible infestations can be localized, using combines that lack straw or chaff spreaders, mowing jointed goatgrass found along roadsides, fields or waste areas, as well as using cultural practices . These cultural practices include fallowing for one or more growth seasons, long-term crop rotations which would mean growing winter wheat only once every three to four years, and delaying seed planting so that seedbed preparations will destroy jointed goatgrass seedlings (although this may also reduce the yield of winter wheat) . These practices are not completely effective since jointed goatgrass seeds are able to persist and can stay in dormancyDormancy
Dormancy is a period in an organism's life cycle when growth, development, and physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be closely associated with environmental conditions...
for up to five years . The best solution is to use several cultural tactics throughout the life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
of jointed goatgrass and at a minimum of three different decision times (during the interval between winter wheat crops, before planting winter wheat, after planting but before winter wheat jointing, and before harvesting) . Other cultural practices include burning the residue after harvest and deep moldboard plowing, although Ball et al. point out that these methods can reduce air quality, increase soil erosion, decrease soil productivity and result in lost organic matter
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
.
Another option for the control of jointed goatgrass is to use deleterious rhizobacteria (DRB) which scientists have already proven can suppress other weeds . However, the success of DRB depends upon its ability to survive which is affected by environmental factors such as soil series
Soil series
Soil series as established by the National Cooperative Soil Survey of the United States Department of Agriculture Natural Resources Conservation Service are a level of classification in the USDA Soil Taxonomy classification system hierarchy. The actual object of classification is the so-called...
, temperature, moisture, and sunlight exposure . The goal for DRB is for it to be a low-cost, effective method for the control of jointed goatgrass with minimum damage to the environment .