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Dyer’s Woad By Jacob Martin |
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Dyer’s
woad is becoming an increasing problem for rangeland managers across the
western states. With an ability to draw precious nutrients from the large tap
roots system and its persistence on disturbed sites, it is a noxious weed in
the state of Idaho that should not be ignored. |
Dyer’s woad is becoming an increasing
problem for rangeland managers across the western states. With an ability to draw precious
nutrients from the large tap roots system and its persistence on disturbed
sites, and are a noxious weed in the state of
Identification
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Dyer’s Woad (Isatis tinctoria L.) is a flowering forb/herb that
ranges from one to four feet tall, but is usually about two feet in height
(Washington State Weed Control Board 1999). The tap root reaches up to five
feet in depth (O’ Donnell 1999). The bluish-green rosette leaves are covered
with hair and range from one to seven inches in length with a whitish cream on
the upper part of the leaf blade (Washington State Weed Control Board 1999).
Dyer’s Woad can produce up to 20 rosette, but usually establish 7-8 mature
stems that have flowering branches. The leaves are cauline with short basal
lobes. The leaves often have smooth edges and are hairless. The small yellow
flowers are gathered in an racemose inflorescence have a flat top and they are
cross shaped with four petals that are twice as long as the four sepals (Guarino
et al. 2000). The fruit is a purplish-brown pod that contains one seed (Weber
County 2001).
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Dyer’s Woad (Isatis tinctoria L.) is a flowering forb/herb that ranges from one to four feet tall, but is
usually about two feet in height (Washington State Weed Control Board
1999). The tap root reaches up to
five feet in depth (O’ Donnell 1999). The bluish-green rosette leaves are
covered with hair and range from one to seven inches in length with a whitish
cream on the upper part of the leaf blade (Washington State Weed Control
Board 1999). Dyer’s Woad can produce up to 20 rosette, but usually establish
7-8 mature stems that have flowering branches. The leaves are cauline
with short basal lobes. The
leaves often have smooth edges and are hairless. The small yellow flowers are gathered
in an racemose inflorescence have a flat top and
they are cross shaped with four petals that are twice as long as the four
sepals (Guarino et al. 2000). The fruit is a purplish-brown pod that
contains one seed (Weber County 2001).
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Background
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Dyer’s woad is
native to southeast Russia, and was first introduced to Utah and the North
Western States in the early 1910’s as a contaminant in alfalfa seed (Kings
County). It is an introduced plant that is believed to have been imported by
early colonist from Europe in the mid 1700’s. The origin of its introduction
is unknown, but has been conceived that it was imported as a source of deep
blue dye (indigo) or as a medicinal plant. (Washington State Weed Control
Board 1999). |
Dyer’s woad is native to southeast |
Habitat and Distribution
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This invader is found mostly in disturbed sites, such as
rangelands. Croplands, dry areas, woodlands, and pasture sites (Weber County).
Dyer’s woad will originally establish along roadsides, gravel pits, levees and
railroad right of ways. It does best in rocky soils with low water holding
capacity, and the highest threat of establishment is in rangelands, pastures
and forests lands (McConnell et al. 1998). You can find dyer’s woad in loose
alkaline bench soils and on south facing canyon slopes with 3,000 to 8,000
feet of elevation (Washington State Weed Control Board 1999). Dyer’s Woad is occasionally found in the eastern U.S., and is considered a serious weed in the western states. Dyer’s woad is common in the central and many of the southern Idaho counties. It more common in southeastern ID, northern Utah, northern California and is spreading into eastern OR (Hawkes 1985). |
This invader is found mostly in disturbed sites, such as rangelands.
Croplands, dry areas, woodlands, and pasture sites (|
 Figure 1. Distribution in Idaho
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Biology and Ecology
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Dyer’s
woad can grow as a winter annual, a biennial or short lived perennial (Dyers
Woad). It is common for the plant to persist for more than one year. The seed
germinate in the fall with rosettes appearing in early spring, and usually
overwinter (Washington State Weed Control Board 1999). The stiff mature stalks
flower from April to June, and sometimes until August in higher elevations.
Even though the plant dies after seed production, resprouting will occur for
several years from the tap root near the crown of the plant (Washington State
Weed Control Board 1999). This noxious weed spreads by seed in the late spring
to mid-summer and can reproduce very quickly spreading 14% each year (O’
Donnell 1999). The fruit of dyer’s woad contains a soluble chemical that
inhibits germination and limits the root elongation of seedlings. This
chemical is flushed away with rains, and most of the seeds will remain dormant
until then. This germination inhibitor contributes to seed bank formation of
dyer’s woad, delaying germination until precipitation levels are favorable for
plant growth (Washington State Weed Control Board 1999). After the seed pod fall to the ground intact, the winter chilling process is necessary before flowering. Each can plant produce 350 to 500 seeds which take 6 to eight weeks to develop, depending on conditions (Washington State Weed Control Board 1999). The seeds are viable in soil for many years and only 1% of fall germinated plants flower the first spring, 35% the second spring, and 12% flowered by the third spring (McConnell et al. 1998), but it doesn’t generally flower until the second year (Dyers Woad). Most of the time the seeds are dispersed along roadsides, waterways and by animals, and can also be spread as a contaminant in feed, crop seed and bedding (Washington State Weed Control Board 1999). The seeds usually fall within 22 inches of the parent plant, but wind can disperse the seed up to 8 feet away (Washington State Weed Control Board 1999). Dyer’s woad is not toxic to livestock but does have a water soluble chemical which inhibits other plants to grow and allows it to out compete other plants. |
Dyer’s
woad can grow as a winter annual, a biennial or
short lived perennial (Dyers Woad). It is common for the plant to persist
for more than one year. The seed
germinate in the fall with rosettes appearing in early spring, and usually overwinter (Washington State Weed Control Board
1999). The stiff mature stalks
flower from April to June, and sometimes until August in higher
elevations. Even though the plant
dies after seed production, resprouting will occur
for several years from the tap root near the crown of the plant (Washington
State Weed Control Board 1999).
This noxious weed spreads by seed in the late spring to mid-summer and
can reproduce very quickly spreading 14% each year (O’ Donnell
1999). The fruit of dyer’s woad contains a soluble chemical that inhibits
germination and limits the root elongation of seedlings. This chemical is flushed away with
rains, and most of the seeds will remain dormant until then. This germination inhibitor contributes
to seed bank formation of dyer’s woad,
delaying germination until precipitation levels are favorable for plant
growth (Washington State Weed Control Board 1999).
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Ecological and Environmental Impacts
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Dyer’s woad (Isatis tinctoria L.) is on the list of 36 noxious
weeds in Idaho and can be found all across the United States. Dyer’s woad is
noxious weed that has been spreading very quickly in croplands and rangelands
of northern Utah and surrounding states (Farah 1988). Croplands, rangelands,
and pasture lands are being overtaken of their native grasses by dyer’s woad,
and most livestock and wildlife will not graze it (Weber County 2001). It
continues to rapidly spread through the Intermountain west displacing native
plants and decreasing livestock and wildlife forage on rangelands in eight
western states (Kings County). This ultimately reduces livestock production
from the loss of desirable species that provided the majority of forage. It is
especially troublesome to managers because it is able to invade healthy
rangelands with or without disturbances (Guarino et al. 2000). With a two-layered rooting system dyer’s woad is able to exploit the surface snow melt with the lateral root and the deep roots are able to utilize water lying below the principle rooting zone of associated herbaceous species (Farah 1988). The rooting seed pods of dyer’s woad are said to allelopathic, contaminating hay fields and rangelands and lowering forage quality (Washington State Weed Control Board 1999). An example of the spread of dyer’s woad can be seen north of Salt Lake City, Utah. It was estimated there was an annual loss of $2 million attributed from the reduced crop yields and loss of rangeland production from an increase of dyer’s woad two fold from 1971 to 1981 (Evens 1981). Even though dyer’s woad is not toxic to livestock, it is closely related to other toxic weeds (Guarino et al. 2000). Dyer’s woad does have beneficial qualities. It is known as a source of blue dye since the 13th century and was widely cultivated in England until 1930 (Washington State Weed Control Board 1999). The chemical know as Indigotine produces a blue dye that is located in the leaves, and is produced through fermentation. |
Ecological and Cultural Impacts:
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Economic and Human Impacts Options
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The economic effect was discussed in past essays pertaining mostly to the blue dye that it produces when fermented. Even though dyer’s woad has the potential to disastrously explode onto local ecosystems, it is sometimes cultivated. The plant is easy to grow in sunny or partly sunny conditions and produce only a small amount of indigtotin throughout the plant (Summit County 2004). Isatis tinctoria is a commonly used herb in traditional Chinese medicine extending back to at least the first century (Isatis tinctoria). As a negative affect dyer’s woad caused a $2 million annual loss in the northern counties of Utah (Washington State Weed Control Board 1999). This is just an example of what dyer’s woad can do if allowed to establish and spread |
The economic effect was discussed in past essays pertaining mostly to
the blue dye that it produces when fermented. Even though dyer’s woad has the potential to disastrously explode onto local
ecosystems, it is sometimes cultivated.
The plant is easy to grow in sunny or partly sunny conditions and
produce only a small amount of indigtotin
throughout the plant (Summit County 2004). Isatis tinctoria is a commonly used herb in
traditional Chinese medicine extending back to at least the first century (Isatis tinctoria). As a negative affect dyer’s woad caused a $2 million annual loss in the northern
counties of |
Management Options
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In
today’s natural resource management, weeds are an ever increasing problem to
land managers. Along with an increase in knowledge of weeds there has been an
increase in technology, including herbicides and mechanical control methods.
This biennial noxious weed has abilities to establish along road sides, gravel
pits, and railroad right-of-ways creating more management problems. With
correct management objectives and efficient use of resources, agencies can
control and prevent the spread of dyer’s woad. Prevention dyers woad from becoming established is the best control method of all (Dyers Woad). The best way to prevent dyer’s woad or any other weed from becoming established is control the roadways, railways, and where hay is fed. Wash stations and signs are a good start to improving the awareness. Obviously, sound management techniques that benefit desirable plants are the first step in a control program. This will allow the native vegetation to out compete dyer’s woad or other invasive plants. Sometimes even good management actions can lead to the spread and establishment of invasive species due to other factors and conditions. There are three basic mechanical methods used in the control of dyer’s woad. One is hand removal which usually occurs after a plant species show seedhead production but before flowering (Mechanical Control Information). This is often a labor intensive and costly method which managers try to combine with other methods. Because of the taproot produced by dyer’s woad there must be many treatments over several years in order to successfully eliminate this plant. Mowing is a method also used by managers to control or eradicate dyer’s woad. Mowing consists of the use of a tractor and PTO mower that will remove foliage and prevent the plant from producing seed. This often will cause soil damage from the weight of the tractor. Tillage is the last control method that has been shown potential from success. This is a method that uses a tractor and equipment such as plows, discs, and rototillers. The initial point of this method is to remove the vegetative structure and incorporate it into the soil profile (Mechanical Control Information). Obviously there will be soil degradation issues, but the idea is to totally eradicate the weed. Biological organisms are another tool used to control the invasion of a weed. Unfortunately no animal or insect has been discovered that will prefer dyer’s woad to other plants. There is however a native rust pathogen (fungus) called Puccinia thlaspeos which stunts growth and can minimize seed production of dyer’s woad (Kropp 1997). This rust will not spread and may not reach many infestations. This rust is especially promising in rugged areas where herbicide sprays or mechanical means are impractical (Dyers Woad). Sheep readily consume top growth of dyer’s woad until flowering stage which can provide a limited control method. Recent studies have shown that properly timed grazing, repeated several times per season may increase mortality and reduce reproductive performance (McConnell et al. 1998). Using a planned herbicide control program, dyer’s woad can be prevented from further spreading or establishment. When selecting a proper chemical for application, several factors should be evaluated, such as cost, location, and non-target species present. When controlling large infestations, metsulfuron (Ally® or Escort®) at ½ oz. per acre can be used to minimize seed production (Washington State Weed Control Board 1999). With a combination of metsulfuron (Ally® or Escort®) with 2,4-D and application before the plant bolts is the best herbicide control method for dyer’s woad (Washington State Weed Control Board 1999). Most control efforts for large infestations have not been effective and control with herbicides depends on the value of the rangeland. |
In today’s natural resource management, weeds are an ever
increasing problem to land managers.
Along with an increase in knowledge of weeds there has been an increase
in technology, including herbicides and mechanical control methods. This biennial noxious weed has
abilities to establish along road sides, gravel pits, and railroad
right-of-ways creating more management problems. With correct management objectives and
efficient use of resources, agencies can control and prevent the spread of
dyer’s woad.
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Additional Resources
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Dyers Woad.<http://www.cdeaton.com/GrandviewHeights/NoxiousWeeds/dyers_woad.html> Accessed 2005, March 6.
Evens, J.O. and R.L. Chase. 1981, Dyers woad control. EL-199, Coop. Ext. Serv., Utah State Univ., Logan. 2pp.
Farah, K.O., A.F. Tanaka and N.E. West. 1988. Autecology and population biology of Dyer’s woad (Isatis tinctoria L.).
Weed Sci. 36:186-193.
Guarino, C., P. Casoria, and B. Menale. 2000. Cultivation and use of Isatis tinctoria L. (Brassicaceae) in Southern Italy. Economic Botany. 54:395-400.
Isatis tinctoria – monograph. 2002. Alternative Medicine Review. <http://www.findarticles.com/p/articles/mi_m0FDN/is_6_7/ai_96416604>
Kings County: Natural Resource and Parks. <http://dnr.metrokc.gov/wlr/lands/weeds/woadd.htm> Accessed 2005, March 7.
McConnell, E.G., J.O. Evens and S. A. Dewey. 1998. In
Biology and Management of
Rangeland Weeds. R. Sheley.
Mechanical Control Methods. 2005. Control methods
that have been used with success http://el.erdc.usace.army.mil/pmis/mechanical/html/isatis_t.html
NRCS: Plants Profile. Isatis tinctoria L., Dyer’s Woad. <http://plants.usda.gov> Accessed 2005, March 6.
O’ Donnell, A. 1999. dyers woad, Isatis tinctoria L. (Brassicaceae). <http://mtwow.org/dyers-woad.html> Accessed 2005, March 4.
Washington State Noxious Weed Control Board. 1999. Dyer’s Woad (Isatis tinctoria L.). <http://www.nwcb.wa.gov/weed_info/dyerswoad.html> Accessed 2005, March 6.
Weber County: Weed Abatement. 2001. Traditional methods for controlling Dyers Woad. <http://www.co.weber.ut.us/weeds/types/d_woad.asp> Accessed 2005, March 6.
Welcome to Summit County. 2004. Dyer’s woad integrated
management dyer’s woad
control.
http://www.co.summit.ut.us/services/data/dyerswd.html |
Dyers Woad.<http://www.cdeaton.com/GrandviewHeights/NoxiousWeeds/dyers_woad.html>
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