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Medusahead grows in areas
that have relatively mild to cold temperatures in winter but are hot in summer [75,79].
It is generally found
in areas that receive fall, winter, and spring moisture followed by dry summers
[108]. It occurs in areas with annual precipitation
of 10 to 40 inches (250-1,000 mm), with an
upper limit of precipitation approximately 50 inches (1,270 mm) [75,79,99]. Infestations
primarily occur in former sagebrush-grass or bunchgrass communities that
receive 10 to 20 inches (250-500 mm) of precipitation [79,99]. Areas above 4,500 feet (1,370 m) elevation, and well-drained
coarse soils, may be less susceptible to invasion.
Medusahead often dominates disturbed areas on soils with high moisture-holding
capacities and slow percolation rates [33]. Sites particularly susceptible to medusahead invasion
in the more arid portions of Idaho are either those with well-developed soil
profiles, particularly with high clay content either at or near the surface; or
those occupying topographic positions that receive additional run-off from
adjacent sites. In more mesic climates, moderately well-developed soils are as susceptible
to invasion as well-developed soils. Conversely,
soils with little profile development, particularly those that are well
drained, remain dominated by cheatgrass in early seral stages regardless of
whether they are in a more arid or mesic area [28].
In a northwestern California site where medusahead is prevalent, 60% of the vegetation is grassland
or woodland/grass. The climate is mediterranean, with cool wet winters and hot
dry summers. Mean annual rainfall is 39 inches (980 mm). Soil is fine sandy loam
2 to 3.3 feet (0.6-1.0 m) deep with rapid surface drainage; slope is 10% on a southeast aspect [5,6].
Foothills in southwestern Oregon where medusahead is found have silty clay loam
soil, with 1,600 feet (500 m) elevation and 20-30% slope on a west aspect. On southwest aspects,
medusahead occurs on
5-20% slopes at 2,000 feet (600 m) elevation. The climate has a
mediterranean/maritime pattern with cool, wet winters and hot dry summers and annual
precipitation of 20 inches (500 mm) [14].
Medusahead and cheatgrass are often in
competition with each other, and soil and topographic factors affect
their distribution [28,39]. Each can replace other herbaceous vegetation and
share dominance with the other. Cheatgrass occupies a
larger geographical area than medusahead, extending to drier areas of the
semiarid western U.S. than does medusahead [29].
Cheatgrass will grow in almost any type of soil, although it does best on deep, loamy or
coarse-textured soils and it does not grow as well on fine textured soils (e.g. [32,73,125]).
Medusahead may be more likely to dominate on fine-textured soils in the Intermountain region [118].
In arid conditions, medusahead is more dependent on additional moisture for
survival. This may be because cheatgrass matures when soil moisture is still
plentiful in May, and medusahead does not mature until 3 weeks later when
moisture is more confined to depressions and clay soils [28,39]. Because medusahead matures
approximately 1 month later than cheatgrass, it initially only replaces cheatgrass on soils with
sufficient moisture holding capacity, such as clay textured soils, so that some
soil moisture remains after cheatgrass matures. Medusahead's root system can exploit all soil moisture in the soil profile
[117]. In the Columbia River Basin, medusahead is dominant on
soils high in montmorillonite clay within 10 to 12 inches (25-30 cm) of the surface,
and on soils low in clay but on with favorable topographic positions.
Cheatgrass is dominant on weakly developed soils low in montmorillonite clay.
Medusahead is a major concern to the range livestock industry because it can
suppress desirable vegetation. It is
unpalatable to livestock. When dry, dead vegetation
decomposes slowly and forms a persistent dense litter on the soil
surface. As the plant matures it develops long barbed awns
that can cause injury to the eyes, noses, and mouths of grazing animals
[16,51]. Medusahead has little to no feed value to livestock at any stage of growth
[13,16,83,106]. However, it has been noted that livestock utilize it when
other feed is
limited [83].
Medusahead is not important to wildlife forage [13].
It has invadesd and replaced dense stands of cheatgrass [48,78]
over large areas in California, Idaho, Oregon, and Washington during the past 40 years [124].
Medusahead herbage is less palatable to ungulates than cheatgrass, and reduces grazing capacity
where it replaces cheatgrass [47]. Its seeds are not digestible by upland game birds, which
are large consumers of cheatgrass seeds [92]. Medusahead seed appears to be largely indigestible to chukar and other wild birds
[79,97]. In a controlled study, chukar in medusahead- infested areas ingested
medusahead fruits. However, when diet was limited to medusahead seeds, dramatic weight loss
occurred [97]. Rabbits may occasionally
graze medusahead [99].
Mule deer generally use medusahead very little. A northeastern
Oregon medusahead-rattail fescue (Festuca myuros)-soft chess (Bromus
mollis) community received some spring
and summer use. However, despite the extensive
stands available, medusahead was still the least preferred forage of mule deer
in winter, summer, and fall, and it ranked low in spring. Communities dominated by medusahead
were of little value to mule deer, while cheatgrass-dominated communities receive substantial
use [14]. The dwarf sagebrush species such as low sagebrush and black sagebrush (Artemisia nova)
are
preferred mule deer browse. Medusahead has established in some dwarf sagebrush communities,
and the invasion of such sites by
medusahead has increased the incidence of wildfire as reduced cover of dwarf
sagebrushes. These sites
had previously been considered "fireproof" because of
reduced herbaceous vegetation caused by excessive grazing [23].
Medusahead and cheatgrass (Bromus tectorum), another invasive non-native
species, overlap in distribution and habitat requirements. Each can replace other herbaceous vegetation and
share dominance with the other. Cheatgrass occupies a
larger geographical area than medusahead, which extends to drier areas of the
semi-arid western U.S. [29]. Medusahead maintain its dominance on sites where native
vegetation has been eliminated or severely reduced by overgrazing, cultivation,
or frequent fires [102]. It has invaded seral communities in eastern
Oregon and Idaho and replaced cheatgrass as the dominant alien grass [57]. It has invaded fields, dry roadsides,
and disturbed sagebrush slopes
in British Columbia, Washington, Idaho, Oregon, and California [26,58,60].
Great Basin:
On sagebrush (Artemisia spp.)-dominated habitats in western Great Basin, medusahead usually invades
sites already infested with cheatgrass
[77,93,109,117,118]. In
California, medusahead colonies often border low sagebrush (Artemisia
arbuscula ssp. longicaulis) communities [11]. Associated grasses
in sagebrush-dominated communities with a medusahead component include bottlebrush squirreltail (Elymus
elymoides), Sandberg bluegrass
(Poa secunda) [118], foxtail fescue (Festuca megalura), bluebunch wheatgrass
(Pseudoroegneria spicata), and crested wheatgrass (Agropyron desertorum)
[7,46,49,51,81,99]. Forbs
associated with medusahead in the Great Basin include sunflower (Helianthus annuus) [98,118],
panicle willowweed (Epilobium paniculatum), and gumweed (Grindelia
nana) [118].
A Nevada study found that sites
with sparse native plants are more susceptible to medusahead invasion
than more diverse low sagebrush (Artemisia arbuscula) or woodland/low
sagebrush
communities. If the more diverse communities are degraded
to a "low" seral state, medusahead can invade and occupy the site. Young and
others [119] determined that low sagebrush communities are most susceptible to medusahead
invasion, while big sagebrush (A. tridentata) communities are more resistant [118].
The introduction and subsequent rapid spread of
medusahead has caused serious management concern because of its rapid migration,
vigorous competitive nature, and low forage value. A study by the BLM found
that on public lands administered by the
agency, 3.3 million acres of rangeland are classified as cheatgrass and/or medusahead
monocultures; nearly 14 million acres are infested with 1 or both; and 62.1
million acres are at risk of invasion by these 2 grasses if disturbance occurs
[87]. In some infested areas of southwestern Idaho, it
has reduced grazing capacity as much as 80% [28].
Medusahead invasion has shifted the balance from a
shrub/perennial grass ecosystem to an annual grass-dominated ecosystem [11].
A healthy stand of
perennial vegetation appears to be the best barrier to medusahead invasion [28].
Medusahead invasions are most common on ranges in poor condition. Poor grazing management practices may accelerate the rate of
spread, but proper management alone may not prevent invasion [42]. Cultivated areas are susceptible to
invasion by medusahead, especially old fields. Livestock avoid medusahead when
more palatable forage is available, leading to an abundance of soil-stored
medusahead seed [83]. A combination of treatments including grazing, burning,
mechanical manipulation, herbicide such as atrazine or glyphosate, and/or reseeding are generally necessary to reduce
established stands of medusahead [22,75,79,106].
Mechanical:
Spring
plowing after most medusahead has germinated has given some control, with optimal
results reaching 95% reduction. Besides removing
weeds and preparing a seedbed for native herbs, cultivation may bury some medusahead seeds so
deeply that they cannot emerge. Spring cultivation eliminates medusahead seedlings, and
legumes can then be drilled at a rate of at least 10 pounds per acre [75]. It is best to
sow in late autumn or early spring, using a rangeland drill if possible. Killing
2 successive crops of annual weeds helps ensure the survival of seeded species
[79]. Cultivation method may not be practical in some terrain, such as the generally steep
and rocky terrain of Idaho's medusahead-infested rangelands [79,106].
Grazing and fire:
Vegetative
manipulation, including fire, may benefit cattle and mule deer on
medusahead-dominated sites [77]. Burning
medusahead can destroy large amounts of seeds if the seedhead has not
disseminated, reducing the stand by 60 to 95% in the next growing season [51]. A slow
burn in dense medusahead stands that occur on well-developed soil profiles may reduce seed production. On less developed soil
profiles where prescribed fire is not feasible, grazing livestock when plants are
actively
growing, herbicide treatment, reseeding, or a combination of these methods may be tried
[14,77]. See the "Fire management" section of the Fire Effects section of this
report for further information on controlling medusahead with prescribed
fire.
Reseeding: Revegetation with natives may prevent medusahead from
regaining dominance after control treatments [75]. Reseeding of treated sites should be done with
species that are competitive, have high vigor, and are adapted to the area [79]. The following may be effective: bottlebrush squirreltail, bluebunch wheatgrass, intermediate wheatgrass (Elytrigia
intermedia), Thurber needlegrass (Achnatherum
thurberianum),
needle-and-thread grass (Hesperostipa comata), Indian ricegrass (A.
hymenoides),
Sandberg bluegrass, and sheep fescue (Festuca ovina) [79,106,107].
Bottlebrush squirreltail may be an especially promising candidate for restoring
rangeland dominated by undesirable exotic grasses such as medusahead. It germinates readily, self pollinates, rapidly reaches reproductive
maturity, and is capable of growth in cool temperatures [4,63]. Bottlebrush squirreltail seedlings appear better able to store
sufficient carbohydrate root reserves under competition with annuals than most
other perennial grass species in the Intermountain region
[56]. Bottlebrush squirreltail is also fire
tolerant and has excellent seed dispersal. Since bottlebrush squirreltail
typically occurs in early seres, wildfire or prescribed burns may provide
opportunities for it to establish [63].
Medusahead increases under frequent fires at the expense of native species and
sometimes, cheatgrass. It promotes further frequent fire by increasing fuel
loads [27,76]. Accumulated medusahead litter enables stand-replacement fires to occur in
ecosystems such as low sagebrush sites that,
under "pristine" conditions, may have been fire-resistant
[11,116,119,122]. Wildfires in medusahead-infested
areas usually minimally damage
soil surfaces and soil erosion is limited, but enough medusahead seed survives to
produce thinned, vigorous stand of multiculmed medusahead plants the following year. Within
a few years, stand densities approach prefire levels [54].
In cheatgrass and medusahead wildfires, accumulation of litter and the rapidity at which the litter
combusts lead to soil heating of
such short duration that nitrate levels may increase. Wildfire-induced increases
in soil nitrate in cheatgrass and medusahead-dominated areas are undesirable: Medusahead is nitrophilic
and readily germinates in seedbeds with high nitrate levels. Near Alturas, California, a wind-driven wildfire
rapidly spread across a medusahead-dominated area. The litter did not completely
ash and there were still viable medusahead fruits in the lightly
charred litter. Bioassays of the burned soil found over 6.2x106
germinable seeds of medusahead per acre (unpublished data; R. R. Blank, USDA/ARS,
Reno, NV) [10].
Fire eliminates some medusahead seed and removes medusahead litter. It also places the
remaining seed in contact with mineral soil where it can germinate and
subsequently be destroyed by future treatments such as tillage and herbicide use
[108]. Contact with aqueous slurries of heated soil significantly (p<0.05) reduced the rate
and success of emergence of medusahead
seedlings compared with a control [12].
Medusahead is
entirely dependent upon seed production for regeneration. It is an extremely capable
seeder because of its large annual
production of viable seed, and because its seed maintains viability in
litter and soil for at least 1 year [99]. Medusahead maintains a
short-lived seedbank [10,62,99]. Plants produce up to 6,000 seeds/ft2
of soil, propagating dense
stands in succeeding years [75]. Medusahead is principally self fertile. Most of the
pollen grains are dispersed within the floret and only a moderate number of
pollen grains are produced in each of the short anthers [41]. Some
cross-pollination is effected by wind [18].
Animals, wind, and water disperse the seed, and spread is rapid
[42]. A long, rough awn aids in animal dispersal of seed, and medusahead often 1st establishes along
domestic sheep and cow trails [83]. Seeds are dispersed primarily from the coats
and intestinal tracts of grazing animals [42,75,99,109]. Germinable seeds have been recovered in fecal material 4
to 9 days after ingestion by rabbits and domestic sheep, respectively [99]. Stiff barbs pointing in
1 direction enable the
seeds to work into the duff and top layers of the soil. Seeds may germinate in fall, winter, or
spring;
fall germination is most common [6,99,116]. Seedlings
from all seasons produce seeds by early summer [116]. Seeds germinating
in the top layer of litter without soil contact may die during the 1st dry
spell [61,75]. Medusahead usually germinates faster than its competitors. Germination
has been observed 8 to 10 hours after moistening at 50 degrees
Fahrenheit (10 oC) [49]. Germination rates are often over 90% [99]. Awn removal
increases the percentage of germination [85].
A Nevada study found that medusahead seedling emergence and growth
is favored by soil movement and pitting of the soil surface because these
conditions maintain favorable soil temperatures and moisture levels [35]. Favorable microsites for germination and
establishment of medusahead are created when plant litter covers the soil
surface. In Nevada, emergence of medusahead germinants under litter was 47 times greater
than emergence of germinants on bare ground by the end of March. By the end of the growing season,
medusahead yield was 4 times greater under litter than on bare soil [34].
Moderate temperatures may encourage medusahead growth and yield. Maximum dry matter production of medusahead was
achieved at a moderate day/night temperature regime of 75/52 degrees Fahrenheit (24/11
oC). Its yield was
reduced by 75% with a high day/night temperature regime of 90/61 degrees Fahrenheit (32/16
oC), and reduced by 50% with a
low day/night temperature regime of 61/41degrees Fahrenheit (16/5 oC) [29].
Medusahead occurs in seral and late-successional plant communities. It has invaded vast
areas formerly dominated by perennial
grasses. Medusahead often colonizes
portions of range previously dominated by cheatgrass [27,57]. The growth
habits, life cycles, and ecological adaptations of medusahead and cheatgrass are
similar, and the annuals typically grow in association until medusahead
becomes dominant and eventually exclusive [16]. Southwestern Idaho stands in which medusahead was sparse were all seral. In
virtually all cases studied, the sites invaded by medusahead had been occupied
previously by seral species, mainly annuals, which had replaced perennial
bunchgrasses depleted by overgrazing, fire, or cultivation [64,79,102].
Medusahead has potential
for successionally
replacing cheatgrass in the 11-inch (280 mm) and above precipitation zone in the northern
Great Basin and elsewhere [54]. Medusahead litter impedes cheatgrass establishment, and may do better in low nitrogen environments
than does cheatgrass [50,51]. Coexistence of cheatgrass and medusahead is most likely in habitats
low in both nitrogen and phosphorus. Cheatgrass is likely to have
the competitive advantage in more fertile habitats unless other environmental factors
(e.g. high clay content) favor
medusahead [29]. In the sagebrush steppe of northeastern California,
Russian-thistle (Salsola kali), tumblemustard
(Sisymbrium altissimum), and cheatgrass form a seral continuum that closes many sagebrush
communities to the establishment of perennial seedlings. Medusahead has extended the seral
continuum by replacing cheatgrass on some low sagebrush sites on the Modoc Plateau [118,124].
Cheatgrass usually grows in dense stands
and readily ignites and carries fire. After
fire strikes a cheatgrass-infested community, cheatgrass usually
flourishes. However, medusahead can thrives in the wake of cheatgrass-driven fires
[31].
Medusahead is a seral invader after disturbance [102].
Medusahead often grows in dense stands on disturbed
sites where climax perennial grasses have been removed, often to the exclusion
of other species [51]. The abundance of bluebunch wheatgrass has "significantly" decreased
in the Great Basin because of the invasion of
introduced annuals such as medusahead [81]. Past heavy grazing of
foothills, pastures, and rangelands of southeastern Oregon has resulted in
dominance by annual grasses such as medusahead and annual forbs including
yellow starthistle [15].
Tikdert n weɣyul (Isem usnan: Taeniatherum caput-medusae) d talmest n yemɣi seg twacult n poaceae 
. Sergéi Nevski d amdan amezwaru i yuran fell-as deg useggas n 1934.
Tikdert n weɣyul (Isem usnan: Taeniatherum caput-medusae) d talmest n yemɣi seg twacult n poaceae . Sergéi Nevski d amdan amezwaru i yuran fell-as deg useggas n 1934.
Taeniatherum is a genus of Eurasian and North African plants in the grass family.[3][4][5]
The only recognized species is medusahead (Taeniatherum caput-medusae) which is native to southern and central Europe (from Portugal to European Russia), North Africa (Algeria, Morocco, Tunisia), and Asia (from Turkey and Saudi Arabia to Pakistan and Kazakhstan).[2][6][7][8][9] It is also naturalized in southern Australia, Chile, and parts of North America.[10][11][12][13]
This aggressive winter annual grass is changing the ecology of western rangelands in North America.[14] It was first observed in the United States in Oregon in 1903 by Thomas Howell. Forty-eight percent of the total land area of the United States is rangeland, pastureland, national parks, nature preserves, and other wildlands. These lands are essential for agriculture and for protecting the integrity of ecological systems. Natural areas contain many nonnative plant species that occur as self-sustaining populations in the continental United States, including medusahead. As of 2005, medusahead infested approximately 972,700 acres (3,936 km2) in the 17 western states (from North Dakota south to Texas and west to the Pacific coast), and spreads at an average rate of 12% per year.[15] As medusahead spreads, it can outcompete native vegetation in overgrazed rangelands, reduces land value, and creates a wildfire hazard.[16]
Medusahead was first described Elymus caput-medusae by Carl Linnaeus. Nevski recommended in 1934 that the Russian types of medusahead should be classified in a separate genus, Taeniatherum. In the 1960s, it was suggested by Jack Major of the University of California that there are three geographic and morphologically distinct taxa: T. caput-medusae, T. asperum, and T. crinitum. After traveling in Russia, Major thought the proper classification for the plant introduced to North America was Taeniatherum asperum. The genus was revised in 1986 by the Danish scientist Signe Frederiksen. He made the previously mentioned distinct taxa into subspecies of Taeniatherum caput-medusae.[17]
The subspecies caput-medusae is a native species to Europe, and is mostly restricted to Spain, Portugal, southern France, Algeria, and Morocco. Subspecies crinitum is found from Greece and the Balkans east into Asia, and the range of subspecies asperum completely overlaps the other two subspecies.[17]
In Asia, medusahead is widespread in Turkmenistan, Iran, Syria, and in the northern portion of Israel, inhabiting low mountains and plateau areas. It is both an agronomic and rangeland weed. It prefers soils rich in nitrogen, and is often found on stony or gravelly soils. Carbonized seeds of this weed have been found in early agricultural archaeological sites in Iran. Seeds were first found in strata corresponding to the early days of sheep and goat husbandry.[17]
Medusahead is a winter annual, germinating in the fall and undergoing root growth in the winter and early spring. Since its roots develop early and reach deep in the soil, it outcompetes native plants for moisture. It flowers in early spring, and by June or July its seeds, which are covered with tiny barbs, are mature. The barbs help the seeds attach to livestock, humans or vehicles that pass by. As the grass grows it accumulates silica, making it unpalatable to livestock except for early in its life cycle. It creates a dense layer of litter, and because of the silica content, the litter decomposes more slowly than that of other plants. This litter suppresses native plant growth while encouraging the germination of its own seed, and after a few years it creates an enormous load of dry fuel that can lead to wildfires.[14]
Stands of medusahead vary in density from several hundred to 2,000 plants per square foot. This variance is directly related to annual precipitation, soil type, and other vegetation in the area. Research has suggested that medusahead is highly adaptable and can produce more seeds at a density of one plant per square foot than 1,000 plants per square foot.[14] Since it matures later than most other annuals, it is easy to identify as it is often bright green when the other annuals are brown. As it matures, it turns shades of purple and eventually tan.[14] This unique phenological signature can be utilized in the management of this invasive species. A recently developed method of assessing greenness in aerial color infra-red (CIR) imagery using Normalized Difference Vegetation Index (NDVI) values to differentiate between medusahead and other more desirable species may help land managers determine where control methods are necessary.[18]
Medusahead seeds disperse relatively short distances and dispersal decreases as distance from the plant increases. Seeds are very well adapted for dispersal by adhesion to moving objects. The relatively long period of medusahead seed dispersal from July to October may be an adaptation to increase the likelihood of adhesion to animals.[19]
Medusahead ranges in height from 20 to 60 centimeters.[20] It has slender, weak stems that often branch at the base. It has spike inflorescences similar to those of wheat or rye. The lemmas have long awns and the glumes have shorter ones, giving the seed head a layered look.[21] As the awns dry, they twist and spread in all directions, similar to the snake-covered head of the mythological Medusa. The barbs on the awns help the seed drive into the soil.[22] The grainlike seed may remain viable in the soil for a number of years.[14]
The grazing capacity of land infested with medusahead can be reduced by up to 80%.[23] Wildlife habitat and biodiversity also suffer, and the weed can eventually lead to alterations in ecosystem functions. The impact medusahead can have on species relying on sagebrush is rarely mentioned. It can exacerbate the decline of sage-grouse (genus Centrocercus) as it replaces plant communities that provide critical habitat for the bird.[23]
Other species, such as mule deer and chukar partridges, tend to avoid areas overrun with medusahead because it is not a good food source. In the case of mule deer, a study in Oregon found that even though extensive stands of medusahead were available, those areas (when compared to other plant communities) were least preferred by feeding mule deer in winter, summer, and fall; and they ranked low in the spring. This decrease in feeding was related back to the dominance of medusahead, which deer do not eat, and the subsequent lack of forbs.[24] Chukar partridges will ingest medusahead seeds (caryopses ) if given no other choice. However, if they are given free access to all the medusahead seeds they will eat, they suffered from a significant loss in body weight. Largely undamaged seeds were found in their droppings, suggesting that the digestibility of medusahead by the birds was low.[25]
No single control method will eradicate medusahead. For best results, it is often necessary use a form of integrated pest management that combines two or more of the following methods.
Plowing and disking are two methods of mechanical control. Both methods can effectively control medusahead and can reduce infestation by 65% to 95% the next growing season. Eradication of medusahead by mechanical control by itself is nearly impossible, but when followed by chemical control or revegetation chances for eradication increase dramatically.[14]
Fire is often considered a low cost method of improving rangeland condition. It has been given attention in the control of medusahead because many of the areas infested with it are too rocky or steep for other treatments. Control of medusahead with fire had differing results in California. In some areas, more desirable plant communities came back after a fire, while in other areas medusahead continued to dominate after fire. There are a few guidelines that should be followed when burning medusahead. The burn should be conducted when the seed is in the soft dough stage (when the seeds exude a milky substance when squeezed) in the late spring. The initial fire should be one that is slow burning, something that is easily achieved by burning into the wind. This prevents the fire from advancing too rapidly and ensures that the current year's herbage is burned and periods of maximum temperature are long enough to kill medusahead caryopses. Viable medusahead caryopses are found almost entirely in the litter and on the soil surface.[26]
Past studies on the effectiveness of burning may have given researchers false hope. The caryopses have severe temperature dependent afterripening requirements which prevent seeds from germinating at temperatures above 10˚C for about 180 days after maturity. If these conditions are met, many medusahead caryopses from the litter and soil in burned plots were viable. Since the seeds did not germinate during the afterripening period, researchers were misled into believing they were accomplishing more by burning than was actually the case.[26]
Chemical control can be effective if used in conjunction with other control methods. Glyphosate (Roundup) applied at 0.375 lbs/acre in the early spring before seeds are produced can provide good results. This timing will also limit the damage to nontarget species that develop later in the growing season. Research suggests that burning before chemical application is more effective than chemicals alone.[14] In the late 1960s, a study was conducted that determined the effectiveness of paraquat on medusahead control in different areas of the United States. This study found that paraquat was effective in controlling medusahead in California, but did not suppress the grass in Reno, Nevada. This was significant because it determined that there was no effective herbicide for the simultaneous spraying and reseeding of medusahead infestations.[27]
Medusahead was found to be susceptible to certain root rot fungi including crown rot and take-all, but it was not susceptible to barepatch, browning root rot, and common root rot. The diseases did not reduce the overall weight of the roots, but take-all significantly reduced the overall dry weight of the aboveground shoots. Soil-borne pathogens can have a severe effect on grasses as long as the environmental conditions for the diseases are optimized. Take-all is associated with plants growing in high soil moisture, and like crown rot, it affected medusahead. In contrast, crown rot had the greatest impact on water-stressed plants and therefore may be an effective biological control of grassy weeds in the arid regions of the western U.S. It is also promising because it did not have a significant negative impact on desirable grasses such as western wheatgrass.[28]
Grazing alone is not a good method of medusahead control. For best results, grazing is used as part of an integrated program. It is an efficient management tool as long as the timing and duration of grazing are controlled properly. For example, if grazing is carried out in conjunction with revegetation, the desirable grasses must be established before the grazing can take place, otherwise the revegetation will be futile. In areas where desirable grasses have completed their life cycle by the winter or early spring, grazing during this time can help reduce medusahead. It should still be in a vegetative stage and therefore more palatable to livestock. Grazing in the late spring, summer, and fall is not recommended because it will give medusahead a competitive advantage as cattle graze species other than medusahead. If livestock grazing is a method used to control mature stands of medusahead, the livestock must be moved to a holding area for 10 days to two weeks and fed weed-free feed before they are moved to weed-free areas. This will prevent the seeds that pass through the animals from germinating in areas that are free of medusahead.[14]
Revegetation should be a part of any medusahead management plan. If medusahead is not first controlled, reseeding an infested area will not be successful. The existing medusahead has to be controlled and especially not allowed to produce more seed, and the seed bank in the soil also has to be reduced. This usually takes two or three years, depending on soil moisture and growing conditions. After this, seedling of desirable species can become established. Combining a tillage treatment followed by herbicide is most effective in controlling the weed and promoting desirable plant growth. Squirreltail, bluebunch wheatgrass, crested wheatgrass, intermediate wheatgrass, Thurber's needlegrass, needle and thread, Indian ricegrass, sandberg bluegrass, and sheep fescue are all competitive grasses that work well when renovating an area previously infested with medusahead in the western United States.[14]
Since medusahead seeds are often spread by adhering to humans, animals, and vehicles, it is recommended to restrict these kinds of traffic in infestations to prevent the spread of medusahead. Narrow containment zones of around 3 meters would successfully suppress the invasion of medusahead to surrounding areas.[19]
Plant communities that have high densities of large perennial bunchgrasses are more resistant to medusahead invasion, so managing rangelands to promote and maintain large perennial bunchgrasses is critical to prevent the spread of medusahead. This will reduce the establishment of new infestations, but successful management will also require searching for and eradicating new infestations. Controlling new infestations is more effective, and often more feasible, than trying to control large infestations.[23]
Even if attempts to prevent and control new infestations are not entirely successful, these efforts will slow the rate of spread and give researchers and land managers more time to develop better prevention, restoration, and control methods. Also, slowing the rate of invasion helps promote rangeland health and productivity in areas that are most at risk of invasion. Without an active prevention program, this weed will continue to spread and increase its negative ecological and economical impacts. Managing medusahead may seem expensive per acre, but when all the acres that are protected by managing an infestation are considered, the price is very reasonable. And, when taking into account the rising land prices, the cost of medusahead management to the individual livestock producer is rapidly becoming more reasonable compared to purchasing additional acreage to offset production losses from medusahead invasion.[23]
Taeniatherum is a genus of Eurasian and North African plants in the grass family.
The only recognized species is medusahead (Taeniatherum caput-medusae) which is native to southern and central Europe (from Portugal to European Russia), North Africa (Algeria, Morocco, Tunisia), and Asia (from Turkey and Saudi Arabia to Pakistan and Kazakhstan). It is also naturalized in southern Australia, Chile, and parts of North America.
This aggressive winter annual grass is changing the ecology of western rangelands in North America. It was first observed in the United States in Oregon in 1903 by Thomas Howell. Forty-eight percent of the total land area of the United States is rangeland, pastureland, national parks, nature preserves, and other wildlands. These lands are essential for agriculture and for protecting the integrity of ecological systems. Natural areas contain many nonnative plant species that occur as self-sustaining populations in the continental United States, including medusahead. As of 2005, medusahead infested approximately 972,700 acres (3,936 km2) in the 17 western states (from North Dakota south to Texas and west to the Pacific coast), and spreads at an average rate of 12% per year. As medusahead spreads, it can outcompete native vegetation in overgrazed rangelands, reduces land value, and creates a wildfire hazard.
Taeniatherum caput-medusae, esperante hordeo kapo de meduzo, estas herbo de la familio de poaceae.
Ĝi estas unujara. Ĝia floraro estas spiko. Eksteraj paleoj longas 4–12 mm, aristoj longas 5–12 cm.
Ĝi ŝatas stonaj lokoj aŭ sekaj agroj.
Usililago phrygica, Puccinia graminis, Fusarium arthrosporioides, Tilletia bornmuelleri.
Origine ĝi vivis en mediteranea ekoprovinco de la palearktisa ekozono, nuntempe temas ankaŭ pri invada specio en Usono.
Taeniatherum caput-medusae, esperante hordeo kapo de meduzo, estas herbo de la familio de poaceae.
Taeniatherum es un género monotípico de plantas herbáceas de la familia de las gramíneas o poáceas.[1] Su única especie, Taeniatherum caput-medusae, es originaria de la región del Mediterráneo hasta el noroeste de la India.
Algunos autores lo incluyen en el género Elymus.[1]
Son plantas anuales que alcanzan un tamaño de 20-40 (-50) cm de altura. Tallos erectos o ascendentes, frecuentemente geniculados en los nudos, glabros. Hojas más superiores espatiformes antes de la antesis; vaina pubérula con pelos de menos de 0,2 mm; lígula de 0,3-0,4 mm; limbo de 3,5-12 x 0,1-0,5 cm, laxamente hirsuto, con pelos rígidos de 1 mm. Espiga de 2-3,5 cm. Glumas de c. 2,5-6 cm, patentes e incurvas en la madurez. Lema fértil de 8-16 cm (incluida la arista), pustulada, escábrida o lisa, con arista recta en la antesis, retorcida y geniculada en la madurez. Pálea de 6-8 mm, linear-elíptica, truncada. Anteras de 1 mm. 2n = 14 (Huelva). Florece y fructifica de abril a mayo. [2]
Se encuentra en los pastizales generalmente secos sobre suelos ácidos. Aparece en lugares rocosos y pedregosos, principalmente en laderas y en garrigas, campos secos. Frecuente en la península ibérica en Zújar, Los Pedroches, Sierra Norte, Aracena, Andévalo y Vega del Guadalquivir. Región mediterránea.
Taeniatherum caput-medusae fue descrita por (L.) Nevski y publicado en Trudy Bot. Inst. Akad. Nauk S.S.S.R., Ser. 1, Fl. Sist. Vyssh. Rast. 1: 22 (1933), in obs.; in Acta Univ. As. Med. Ser. VIII b, Bot. Fasc. 38 (1934)[3]
Taeniatherum: nombre genérico que deriva del griego tenia = (cinta) y ather = (arista), en alusión a la lema con aristas de base plana.
Tiene un número de cromosomas de: x = 7. 2n = 14. 2 ploidias.
Taeniatherum es un género monotípico de plantas herbáceas de la familia de las gramíneas o poáceas. Su única especie, Taeniatherum caput-medusae, es originaria de la región del Mediterráneo hasta el noroeste de la India.
Algunos autores lo incluyen en el género Elymus.
Hatune odrik (Taeniatherum crinitum) on kõrreliste sugukonda kuuluv taimeliik.
Taim kasvab ka Eestis.[1]
Hatune odrik (Taeniatherum crinitum) on kõrreliste sugukonda kuuluv taimeliik.
Taim kasvab ka Eestis.
Kare odrik (Taeniatherum caput-medusae) on kõrreliste sugukonda kuuluv taimeliik.
Taim on kantud Eesti ohustatud liikide punasesse nimestikku.[1]
Kare odrik (Taeniatherum caput-medusae) on kõrreliste sugukonda kuuluv taimeliik.
Taim on kantud Eesti ohustatud liikide punasesse nimestikku.
Taeniatherum caput-medusae, l'Orge chevelue, est une espèce de plantes herbacées méditerranéennes de la famille des Poacées.
Selon World Checklist of Selected Plant Families (WCSP) (4 janvier 2014)[2] :
Selon NCBI (4 janvier 2014)[3] :
Selon The Plant List (4 janvier 2014)[1] :
Selon Tropicos (4 janvier 2014)[4] (Attention liste brute contenant possiblement des synonymes) :
Taeniatherum caput-medusae, l'Orge chevelue, est une espèce de plantes herbacées méditerranéennes de la famille des Poacées.
Taeniatherum caput-medusae é uma espécie de planta com flor pertencente à família Poaceae.
A autoridade científica da espécie é (L.) Nevski, tendo sido publicada em Trudy Sredne-Aziatskogo Gosudarstvennogo Universiteta. Seriya 8b. Botanika 17: 38. 1934.[1]
O seu nome comum é cabeça-de-medusa.[2]
Trata-se de uma espécie presente no território português, nomeadamente em Portugal Continental.
Em termos de naturalidade é nativa da região atrás indicada.
Não se encontra protegida por legislação portuguesa ou da Comunidade Europeia.
Taeniatherum caput-medusae é uma espécie de planta com flor pertencente à família Poaceae.
A autoridade científica da espécie é (L.) Nevski, tendo sido publicada em Trudy Sredne-Aziatskogo Gosudarstvennogo Universiteta. Seriya 8b. Botanika 17: 38. 1934.
O seu nome comum é cabeça-de-medusa.
Taeniatherum caput-medusae là một loài thực vật có hoa trong họ Hòa thảo. Loài này được (L.) Nevski miêu tả khoa học đầu tiên năm 1933.[1]
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Taeniatherum caput-medusae là một loài thực vật có hoa trong họ Hòa thảo. Loài này được (L.) Nevski miêu tả khoa học đầu tiên năm 1933.
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