Ragweed
Encyclopedia
Ragweeds are flowering plants in the genus Ambrosia in the sunflower family
Asteraceae
. Common names include bitterweeds and bloodweeds.
The name Ambrosia
is sometimes claimed to be derived from the Ancient Greek
term ἀμβροσία referring to the food of the gods of Mount Olympus that confered immortality. The term might refer to the tenacity of the plants, which makes it hard to rid an area of them if they occur as invasive weeds.
The genus is best known for the severe and widespread allergies caused by its pollen
.
Ragweeds occur in temperate
regions of the Northern Hemisphere
and South America
. Ragweeds prefer dry, sunny grassy plains, sandy soils, river
banks, roadsides, and ruderal sites
(disturbed soils) such as vacant lots and abandoned fields.
There are 41 species
worldwide. Many are adapted to the arid
climates of the desert
. Burrobush (A. dumosa) is one of the most arid-adapted perennials in North America
. About 10 species occur in the Sonoran Desert
.
This genus is not to be confused with Kochia scoparia
, which also has the common name
"ragweed".
Ragweeds are annuals
, perennials
, and shrub
s and subshrub
s (called bursages), with erect, hispid
stems
growing in large clumps to a height of usually . The stems are basally branched. They form a slender taproot
or a creeping rhizome
. Common Ragweed (A. artemisiifolia) is the most widespread of this genus in North America
. It attains a height of about a meter. Great Ragweed (Ambrosia trifida
) may grow to four meters or more.
The foliage is grayish to silvery green with bipinnatifid, deeply lobed leaves
with winged petioles; in the case of Ambrosia coronopifolia, the leaves are simple. The leaf arrangement is opposite at the base but becomes alternate higher on the stem.
Ambrosia is a monoecious plant, i.e., it produces separate male and female flower heads on the same plant. The numerous tiny male inflorescences are yellowish-green disc flowers about in diameter. They grow in a terminal spike, subtended by joined bract
s. The whitish-green single female flowers are inconspicuously situated below the male ones, in the leaf axils. A pappus
is lacking.
After wind pollination
, the female flower develops into a prickly, ovoid burr with 9-18 straight spines. It contains one arrowhead-shaped seed, brown when mature, and smaller than a wheat grain. This burr gets dispersed by clinging to the fur or feathers of animals passing by.
The seeds are an important winter food for many bird species. Ragweed plants are used as food by the larva
e of a number of Lepidoptera
(butterflies and moths); see list of Lepidoptera that feed on ragweeds.
over a season, and the plant is anemophilous (wind-pollinated
). It is highly allergenic, generally considered the greatest allergen
of all pollens, and the prime cause of hay fever
in North America. Common Ragweed (A. artemisiifolia) and Western Ragweed A. psilostachya
are considered the most noxious to those prone to hay fever. Ragweeds bloom in the Northern Hemisphere from early July until mid-August or until cooler weather arrives. According to a recent study, lengthening of the pollen season has been observed in the North America, probably as a result of global warming
.
A plant usually produces pollen more copiously in wet years. When the humidity rises above 70 percent, however, the pollen tends to clump and is not so likely to become airborne. Ragweed is a plant of concern in the global warming
issue, because tests have shown that higher levels of carbon dioxide
will greatly increase pollen production. On dry windy days, the pollen will travel many kilometers.
Goldenrod
is frequently blamed for hay fever but simply happens to have a showy flower
that blooms about the same time. Goldenrod is entomophilous
, i.e., insect
-pollinated. Its pollen is heavy and sticky and cannot become airborne.
Some high mountain and desert areas of North America used to be refuges for severe hay fever sufferers, who would go to such areas for relief during the pollen season, but increased human activity, such as building and other disturbances of the soil, irrigation, and gardening, have encouraged ragweed to spread to these areas as well. Ragweed pollen can remain airborne for days and travel great distances, affecting people hundreds of miles away. It can even be carried 300 to 400 miles (643.7 km) out to sea. Today, no area in the United States
is free of ragweed pollen, and moving can only offer a degree of relief. Ragweeds native to the Americas were accidentally introduced to Europe starting in the nineteenth century and particularly during World War I
; they thrived and have greatly spread since the 1950s. Eastern Europe, particularly Hungary
, has been badly affected by ragweed since the early 1990s, when the dismantling of Communist collective agriculture led to large-scale abandonment of agricultural land, and new building projects also resulted in disturbed, un-landscaped acreage.
Anecdotal claims are made of honey
giving some relief for ragweed pollen allergies
, which is noteworthy because honeybees very rarely visit ragweed flowers, and even then, only for pollen. However, during ragweed pollen shed, the pollen dusts every surface, and honeybees, being electrostatically charged, will accumulate some ragweed pollen. The pollen is frequently identified
as a component of raw honey.
The major allergenic protein
has been identified as Amb a 1, a 38 kDa
nonglycosylated protein
composed of two subunit
s. Other allergens widespread among pollen—profilin
and calcium-binding protein
s—are also present.
Chemical spraying is effective for control in large areas. Because ragweed only reacts to some of the more aggressive herbicides, it is highly recommended to consult professionals when deciding on dosage and methodology, especially near urban areas. Effective active ingredients include those that are glyphosate-based (Roundup, Glyphogan, Glialka), sulfosate-based (Medallon), and glufosinate ammonium-based (Finale 14SL). In badly infested areas usually 2 to 6.5 liters of herbicides are dispersed per hectare
(approx. 0.2 to 0.7 US gallon
s per acre
).
Where the plant is controlled by reaping, in populated areas and near delicate plantings that limit herbicide
use, mowing should be repeated continuously every three weeks because it is difficult to cut the plant right at the soil level, and it will regrow in two weeks (and often branch into three or four full-sized stems) if more than half an inch remains above the ground.
A previously favored method of controlling ragweed was cutting it, leaving the cuts in the field, then burning them there once the stalks had dried, since standing, live ragweed will not burn. It is less popular today, because the smoke produced is seen as unacceptable pollution
, as with the decline in leaf-burning and trash burning. The method has the added benefit of killing off the stems so the plant does not grow back, which is otherwise almost inevitable.
Manually uprooting ragweed, sometimes shown in the media for public awareness purposes, promises more than it can deliver. It is ineffective, and skin contact may cause the onset of full-blown hay fever
symptoms in persons with latent ragweed hypersensitivity. That being said, ragweed is best uprooted in late spring, before the flowering season and before a strong root system has developed.
There is evidence that mechanical and chemical control methods are actually no more effective in the long run than leaving the weed alone.
Fungal rust
s and especially the leaf-eating beetle Ophraella communa have been proposed for biological control to be used against ragweed, but the latter may be dangerous to sunflower
s and there have been problems obtaining permits and funding to test such controls.
Ambrosia mexicana is actually the Jerusalem Oak Goosefoot
(Chenopodium botrys), an entirely unrelated plant.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
. Common names include bitterweeds and bloodweeds.
The name Ambrosia
Ambrosia
In ancient Greek mythology, ambrosia is sometimes the food or drink of the Greek gods , often depicted as conferring ageless immortality upon whoever consumes it...
is sometimes claimed to be derived from the Ancient Greek
Ancient Greek
Ancient Greek is the stage of the Greek language in the periods spanning the times c. 9th–6th centuries BC, , c. 5th–4th centuries BC , and the c. 3rd century BC – 6th century AD of ancient Greece and the ancient world; being predated in the 2nd millennium BC by Mycenaean Greek...
term ἀμβροσία referring to the food of the gods of Mount Olympus that confered immortality. The term might refer to the tenacity of the plants, which makes it hard to rid an area of them if they occur as invasive weeds.
The genus is best known for the severe and widespread allergies caused by its pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
.
Ragweeds occur in temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
regions of the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
. Ragweeds prefer dry, sunny grassy plains, sandy soils, river
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
banks, roadsides, and ruderal sites
Ruderal species
A ruderal species is a plant species that is first to colonize disturbed lands. The disturbance may be natural , or due to human influence – constructional , or agricultural .Ruderal species typically dominate the disturbed area...
(disturbed soils) such as vacant lots and abandoned fields.
There are 41 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
worldwide. Many are adapted to the arid
Arid
A region is said to be arid when it is characterized by a severe lack of available water, to the extent of hindering or even preventing the growth and development of plant and animal life...
climates of the desert
Desert
A desert is a landscape or region that receives an extremely low amount of precipitation, less than enough to support growth of most plants. Most deserts have an average annual precipitation of less than...
. Burrobush (A. dumosa) is one of the most arid-adapted perennials in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. About 10 species occur in the Sonoran Desert
Sonoran Desert
The Sonoran Desert is a North American desert which straddles part of the United States-Mexico border and covers large parts of the U.S. states of Arizona and California and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. It is one of the largest and hottest...
.
This genus is not to be confused with Kochia scoparia
Kochia scoparia
Bassia scoparia is a shrub which is native to Eurasia. It has introduced populations in many parts of North America, where it is found in grassland, prairie, and desert shrub ecosystems...
, which also has the common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
"ragweed".
Description and Ecology
Annual plant
An annual plant is a plant that usually germinates, flowers, and dies in a year or season. True annuals will only live longer than a year if they are prevented from setting seed...
, perennials
Perennial plant
A perennial plant or simply perennial is a plant that lives for more than two years. The term is often used to differentiate a plant from shorter lived annuals and biennials. The term is sometimes misused by commercial gardeners or horticulturalists to describe only herbaceous perennials...
, and shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s and subshrub
Subshrub
A subshrub or dwarf shrub is a short woody plant. Prostrate shrub is a similar term.It is distinguished from a shrub by its ground-hugging stems and lower height, with overwintering perennial woody growth typically less than 10–20 cm tall, or by being only weakly woody and/or persisting...
s (called bursages), with erect, hispid
Trichome
Trichomes are fine outgrowths or appendages on plants and certain protists. These are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae.- Algal trichomes :...
stems
Plant stem
A stem is one of two main structural axes of a vascular plant. The stem is normally divided into nodes and internodes, the nodes hold buds which grow into one or more leaves, inflorescence , conifer cones, roots, other stems etc. The internodes distance one node from another...
growing in large clumps to a height of usually . The stems are basally branched. They form a slender taproot
Taproot
A taproot is an enlarged, somewhat straight to tapering plant root that grows vertically downward. It forms a center from which other roots sprout laterally.Plants with taproots are difficult to transplant...
or a creeping rhizome
Rhizome
In botany and dendrology, a rhizome is a characteristically horizontal stem of a plant that is usually found underground, often sending out roots and shoots from its nodes...
. Common Ragweed (A. artemisiifolia) is the most widespread of this genus in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. It attains a height of about a meter. Great Ragweed (Ambrosia trifida
Ambrosia trifida
Common names: Buffalo Weed, Great Ragweed, Giant Ragweed, Bitterweed, Bloodweed, Horse Cane, Tall AmbrosiaAmbrosia trifida is an annual plant in the aster family, native throughout much of North America. Its flowers are green and are pollinated by wind rather than by insects, and the pollen is one...
) may grow to four meters or more.
The foliage is grayish to silvery green with bipinnatifid, deeply lobed leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
with winged petioles; in the case of Ambrosia coronopifolia, the leaves are simple. The leaf arrangement is opposite at the base but becomes alternate higher on the stem.
Ambrosia is a monoecious plant, i.e., it produces separate male and female flower heads on the same plant. The numerous tiny male inflorescences are yellowish-green disc flowers about in diameter. They grow in a terminal spike, subtended by joined bract
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
s. The whitish-green single female flowers are inconspicuously situated below the male ones, in the leaf axils. A pappus
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
is lacking.
After wind pollination
Anemophily
Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Anemophilous plants may be either gymnosperms or angiosperms ....
, the female flower develops into a prickly, ovoid burr with 9-18 straight spines. It contains one arrowhead-shaped seed, brown when mature, and smaller than a wheat grain. This burr gets dispersed by clinging to the fur or feathers of animals passing by.
The seeds are an important winter food for many bird species. Ragweed plants are used as food by the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of a number of Lepidoptera
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
(butterflies and moths); see list of Lepidoptera that feed on ragweeds.
Ragweed pollen as an allergen
Each plant is reputed to be able to produce about a billion grains of pollenPollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
over a season, and the plant is anemophilous (wind-pollinated
Pollination
Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...
). It is highly allergenic, generally considered the greatest allergen
Allergen
An allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....
of all pollens, and the prime cause of hay fever
Hay Fever
Hay Fever is a comic play written by Noël Coward in 1924 and first produced in 1925 with Marie Tempest as the first Judith Bliss. Laura Hope Crews played the role in New York...
in North America. Common Ragweed (A. artemisiifolia) and Western Ragweed A. psilostachya
Ambrosia psilostachya
Ambrosia psilostachya is a species of ragweed known by the common names Cuman ragweed, perennial ragweed, and western ragweed....
are considered the most noxious to those prone to hay fever. Ragweeds bloom in the Northern Hemisphere from early July until mid-August or until cooler weather arrives. According to a recent study, lengthening of the pollen season has been observed in the North America, probably as a result of global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
.
A plant usually produces pollen more copiously in wet years. When the humidity rises above 70 percent, however, the pollen tends to clump and is not so likely to become airborne. Ragweed is a plant of concern in the global warming
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
issue, because tests have shown that higher levels of carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
will greatly increase pollen production. On dry windy days, the pollen will travel many kilometers.
Goldenrod
Goldenrod
Solidago, commonly called goldenrods, is a genus of about 100 species of flowering plants in the family Asteraceae. Most are herbaceous perennial species found in the meadows and pastures, along roads, ditches and waste areas in North America. There are also a few species native to Mexico, South...
is frequently blamed for hay fever but simply happens to have a showy flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
that blooms about the same time. Goldenrod is entomophilous
Entomophily
Entomophily is a form of pollination whereby pollen is distributed by insects. Several insect are reported to be responsible for the pollination of many plant species, particularly bees, Lepidoptera , wasps, flies, ants and beetles. Some plant species co-evolved with a particular pollinator, such...
, i.e., insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
-pollinated. Its pollen is heavy and sticky and cannot become airborne.
Some high mountain and desert areas of North America used to be refuges for severe hay fever sufferers, who would go to such areas for relief during the pollen season, but increased human activity, such as building and other disturbances of the soil, irrigation, and gardening, have encouraged ragweed to spread to these areas as well. Ragweed pollen can remain airborne for days and travel great distances, affecting people hundreds of miles away. It can even be carried 300 to 400 miles (643.7 km) out to sea. Today, no area in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
is free of ragweed pollen, and moving can only offer a degree of relief. Ragweeds native to the Americas were accidentally introduced to Europe starting in the nineteenth century and particularly during World War I
World War I
World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...
; they thrived and have greatly spread since the 1950s. Eastern Europe, particularly Hungary
Hungary
Hungary , officially the Republic of Hungary , is a landlocked country in Central Europe. It is situated in the Carpathian Basin and is bordered by Slovakia to the north, Ukraine and Romania to the east, Serbia and Croatia to the south, Slovenia to the southwest and Austria to the west. The...
, has been badly affected by ragweed since the early 1990s, when the dismantling of Communist collective agriculture led to large-scale abandonment of agricultural land, and new building projects also resulted in disturbed, un-landscaped acreage.
Anecdotal claims are made of honey
Honey
Honey is a sweet food made by bees using nectar from flowers. The variety produced by honey bees is the one most commonly referred to and is the type of honey collected by beekeepers and consumed by humans...
giving some relief for ragweed pollen allergies
Allergy
An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...
, which is noteworthy because honeybees very rarely visit ragweed flowers, and even then, only for pollen. However, during ragweed pollen shed, the pollen dusts every surface, and honeybees, being electrostatically charged, will accumulate some ragweed pollen. The pollen is frequently identified
Melissopalynology
Melissopalynology is the study of pollen contained in honey and, in particular, the pollen's source. By studying the pollen in a sample of honey, it is possible to gain evidence of the geographical location and genus of the plants that the honey bees visited, although honey may also contain...
as a component of raw honey.
The major allergenic protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
has been identified as Amb a 1, a 38 kDa
Atomic mass unit
The unified atomic mass unit or dalton is a unit that is used for indicating mass on an atomic or molecular scale. It is defined as one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state, and has a value of...
nonglycosylated protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
composed of two subunit
Protein subunit
In structural biology, a protein subunit or subunit protein is a single protein molecule that assembles with other protein molecules to form a protein complex: a multimeric or oligomeric protein. Many naturally occurring proteins and enzymes are multimeric...
s. Other allergens widespread among pollen—profilin
Profilin
Profilin is an actin-binding protein involved in the dynamic turnover and restructuring of the actin cytoskeleton. It is found in all eukaryotic organisms in most cells. Profilin is important for spatially and temporally controlled growth of actin microfilaments, which is an essential process in...
and calcium-binding protein
Calcium-binding protein
Calcium-binding proteins are proteins that participate in calcium cell signalling pathways by binding to Ca2+.The most ubiquitous Ca2+-sensing protein, found in all eukaryotic organisms including yeasts, is calmodulin....
s—are also present.
Control and eradication
Total eradication of ragweed is impossible, bar viral gene therapy methods, owing to the plant's frugality and tremendous seed-producing capability, but control is important to minimize its spread and reduce its effect on the allergic. However, control and eradication may not be the best means to attain this desired end.Chemical spraying is effective for control in large areas. Because ragweed only reacts to some of the more aggressive herbicides, it is highly recommended to consult professionals when deciding on dosage and methodology, especially near urban areas. Effective active ingredients include those that are glyphosate-based (Roundup, Glyphogan, Glialka), sulfosate-based (Medallon), and glufosinate ammonium-based (Finale 14SL). In badly infested areas usually 2 to 6.5 liters of herbicides are dispersed per hectare
Hectare
The hectare is a metric unit of area defined as 10,000 square metres , and primarily used in the measurement of land. In 1795, when the metric system was introduced, the are was defined as being 100 square metres and the hectare was thus 100 ares or 1/100 km2...
(approx. 0.2 to 0.7 US gallon
Gallon
The gallon is a measure of volume. Historically it has had many different definitions, but there are three definitions in current use: the imperial gallon which is used in the United Kingdom and semi-officially within Canada, the United States liquid gallon and the lesser used United States dry...
s per acre
Acre
The acre is a unit of area in a number of different systems, including the imperial and U.S. customary systems. The most commonly used acres today are the international acre and, in the United States, the survey acre. The most common use of the acre is to measure tracts of land.The acre is related...
).
Where the plant is controlled by reaping, in populated areas and near delicate plantings that limit herbicide
Herbicide
Herbicides, also commonly known as weedkillers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic "imitations" of plant...
use, mowing should be repeated continuously every three weeks because it is difficult to cut the plant right at the soil level, and it will regrow in two weeks (and often branch into three or four full-sized stems) if more than half an inch remains above the ground.
A previously favored method of controlling ragweed was cutting it, leaving the cuts in the field, then burning them there once the stalks had dried, since standing, live ragweed will not burn. It is less popular today, because the smoke produced is seen as unacceptable pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, as with the decline in leaf-burning and trash burning. The method has the added benefit of killing off the stems so the plant does not grow back, which is otherwise almost inevitable.
Manually uprooting ragweed, sometimes shown in the media for public awareness purposes, promises more than it can deliver. It is ineffective, and skin contact may cause the onset of full-blown hay fever
Hay Fever
Hay Fever is a comic play written by Noël Coward in 1924 and first produced in 1925 with Marie Tempest as the first Judith Bliss. Laura Hope Crews played the role in New York...
symptoms in persons with latent ragweed hypersensitivity. That being said, ragweed is best uprooted in late spring, before the flowering season and before a strong root system has developed.
There is evidence that mechanical and chemical control methods are actually no more effective in the long run than leaving the weed alone.
Fungal rust
Rust (fungus)
Rusts are plant diseases caused by pathogenic fungi of the order Pucciniales. About 7800 species are known. Rusts can affect a variety of plants; leaves, stems, fruits and seeds. Rust is most commonly seen as coloured powder, composed off tiny aeciospores which land on vegetation producing...
s and especially the leaf-eating beetle Ophraella communa have been proposed for biological control to be used against ragweed, but the latter may be dangerous to sunflower
Sunflower
Sunflower is an annual plant native to the Americas. It possesses a large inflorescence . The sunflower got its name from its huge, fiery blooms, whose shape and image is often used to depict the sun. The sunflower has a rough, hairy stem, broad, coarsely toothed, rough leaves and circular heads...
s and there have been problems obtaining permits and funding to test such controls.
Species
- Ambrosia acanthicarpaAmbrosia acanthicarpaAmbrosia acanthicarpa is a species of ragweed known by the common names flatspine burr ragweed, annual burrweed, and annual bur-sage....
– Flatspine Burr Ragweed, Annual Bursage, Annual Burrweed - Ambrosia ambrosioidesAmbrosia ambrosioidesAmbrosia ambrosioides, also known as canyon ragweed or chicura is a ragweed found in the deserts of northern Mexico and ranging into the southern half of Arizona....
– Ambrosia Burr Ragweed, Canyon Ragweed, chicura- Ambrosia ambrosioides ssp. septentrionale
- Ambrosia artemisiifoliaAmbrosia artemisiifoliaAmbrosia artemisiifolia, Common Ragweed, is the most widespread plant of the genus Ambrosia in North America. It has also been called Annual Ragweed, Bitterweed, Blackweed, Carrot Weed, Hay Fever Weed, Roman Wormwood, Stammerwort, Stickweed, Tassel Weed, and American Wormwood...
– Common Ragweed, Annual Ragweed, American Wormwood, Blackweed, Carrotweed - Ambrosia aspera
- Ambrosia bidentata – Camphor Weed, Lanceleaf Ragweed
- Ambrosia camphorata
- Ambrosia canescens – Hairy Ragweed
- Ambrosia carduacea – Baja California Ragweed
- Ambrosia chamissonisAmbrosia chamissonisAmbrosia chamissonis is a species of ragweed known by the common names Silver Burr Ragweed, Silver Beachweed and Beach Bur....
– Silver Burr Ragweed, Silver Beachweed, Silver Beach Burr, Beach Bur - Ambrosia cheiranthifoliaAmbrosia cheiranthifoliaAmbrosia cheiranthifolia is a rare species of flowering plant known by the common names South Texas ambrosia and Rio Grande ragweed. It is native to the coast of South Texas and the Mexican state of Tamaulipas, where it occurs in coastal prairie, grassland, and mesquite shrubland habitat...
– Rio Grande Ragweed, South Texas Ambrosia - Ambrosia chenopodiifoliaAmbrosia chenopodiifoliaAmbrosia chenopodiifolia is a species of ragweed known by the common name San Diego Burrsage or San Diego Burr Ragweed. It is native to Baja California, and California as far north as San Diego County, where it is a member of the coastal sage scrub plant community. This is a thickly branching shrub...
– San Diego Burr Ragweed, San Diego Bursage - Ambrosia confertifloraAmbrosia confertifloraAmbrosia confertiflora is a species of ragweed known by the common name weakleaf bur ragweed.It is native to much of northern Mexico and the southwestern United States as far east as Kansas and Oklahoma. It is a perennial herb reaching heights between 30 centimeters and nearly two meters with...
– Weakleaf Burr Ragweed - Ambrosia cordifolia – Tucson Burr Ragweed
- Ambrosia deltoidea –Triangleleaf Bursage, Triangle Burr Ragweed, Rabbitbush
- Ambrosia dumosaAmbrosia dumosaAmbrosia dumosa, the burro-weed or white bursage, is a common constituent of the creosote-bush scrub community throughout the Mojave desert of California, Nevada, and Utah and the Sonoran Desert of Arizona and northwestern Mexico....
– Burrobush, Burroweed, White Bursage - Ambrosia eriocentraAmbrosia eriocentraAmbrosia eriocentra is a species of ragweed known by the common names woolly bursage and woollyfruit burr ragweed.It is native to the southwestern United States where it grows in the deserts and surrounding ridges up to about 1700 meters in elevation. This is a rounded shrub reaching over 1.5...
– Woolly Bursage, Woollyfruit Burr Ragweed - Ambrosia grayi – Woollyleaf Burr Ragweed
- Ambrosia helenae
- Ambrosia hispida – Coastal Ragweed
- Ambrosia ilicifoliaAmbrosia ilicifoliaAmbrosia ilicifolia is a species of ragweed known by the common names Hollyleaf Burr Ragweed and Hollyleaf Bursage.It is native to the deserts and mountains of western Arizona and adjacent southeastern California and Baja California, where it grows in dry washes, scrub, and other local habitat....
– Hollyleaf Burr Ragweed, Hollyleaf Bursage - Ambrosia intergradiens
- Ambrosia johnstoniorum
- Ambrosia linearis – Streaked Burr Ragweed
- Ambrosia maritima (the type speciesType speciesIn biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
) - Ambrosia palustris
- Ambrosia pannosa
- Ambrosia parvifolia
- Ambrosia peruviana – Peruvian Ragweed
- Ambrosia psilostachyaAmbrosia psilostachyaAmbrosia psilostachya is a species of ragweed known by the common names Cuman ragweed, perennial ragweed, and western ragweed....
– Western Ragweed, Cuman Ragweed, Perennial Ragweed - Ambrosia pumilaAmbrosia pumilaAmbrosia pumila is a rare species of ragweed known by the common names dwarf burr ragweed and San Diego ambrosia. It is native to far southern California and Baja California where it grows in floodplains and scrub. Today it is known from 19 populations...
– Dwarf Burr Ragweed, San Diego Ambrosia - Ambrosia sandersonii
- Ambrosia scabra
- Ambrosia scabra var. robusta
- Ambrosia scabra var. tenuior
- Ambrosia tarapacana
- Ambrosia tenuifolia – Slimleaf Burr Ragweed
- Ambrosia tomentosaAmbrosia tomentosaAmbrosia tomentosa is a perennial species in the Aster family . This plant grows up to 3 feet tall. The deeply lobed hairy leaves grow to 5 inches and have toothed margins. Flowers are small and yellow and produce spined 2-seeded burrs...
– Skeletonleaf Burr Ragweed - Ambrosia trifidaAmbrosia trifidaCommon names: Buffalo Weed, Great Ragweed, Giant Ragweed, Bitterweed, Bloodweed, Horse Cane, Tall AmbrosiaAmbrosia trifida is an annual plant in the aster family, native throughout much of North America. Its flowers are green and are pollinated by wind rather than by insects, and the pollen is one...
– Great Ragweed, Giant Ragweed, Buffalo Weed- Ambrosia trifida texana – Texan Great Ragweed
- Ambrosia trifolia – Greater Ragweed
- Ambrosia velutina
Ambrosia mexicana is actually the Jerusalem Oak Goosefoot
Jerusalem Oak Goosefoot
Chenopodium botrys, the Jerusalem Oak Goosefoot , also called Feathered Geranium, is a flowering plant in the genus Chenopodium, the goosefoots. It is native to the Mediterranean region....
(Chenopodium botrys), an entirely unrelated plant.
See also
- List of Lepidoptera that feed on ragweeds
- Oral allergy syndromeOral allergy syndromeOral allergy syndrome or OAS is a type of food allergy classified by a cluster of allergic reactions in the mouth in response to eating certain fruits, nuts, and vegetables that typically develops in adult hay fever sufferers....
- RagwortSenecioSenecio is a genus of the daisy family that includes ragworts and groundsels. The flower heads are normally rayed, completely yellow, and the heads are borne in branched clusters...