Ambrosia trifida
(giant ragweed)

Pictures

Picture	Title	Caption	Copyright
Title Leaf Caption Leaf of A. trifida (giant ragweed). Leaves can posess between three and five lobes. Copyright Plant Resources Center/The University of Texas at Austin	Leaf	Leaf of A. trifida (giant ragweed). Leaves can posess between three and five lobes.	Plant Resources Center/The University of Texas at Austin
Title Flowers Caption Male flowers pike with exserted (protruding) anthers and female flowers just visible above the uppermost leaves. Ragweeds are a major contributing factor to autumn hayfever. Copyright Plant Resources Center/The University of Texas at Austin	Flowers	Male flowers pike with exserted (protruding) anthers and female flowers just visible above the uppermost leaves. Ragweeds are a major contributing factor to autumn hayfever.	Plant Resources Center/The University of Texas at Austin
Title Fruits Caption Mature fruits in autumn, still surrounded by bracts. Note that the male heads have fallen from the rachis. Copyright Plant Resources Center/The University of Texas at Austin	Fruits	Mature fruits in autumn, still surrounded by bracts. Note that the male heads have fallen from the rachis.	Plant Resources Center/The University of Texas at Austin

Identity

Preferred Scientific Name

• Ambrosia trifida L.

Preferred Common Name

• giant ragweed

Other Scientific Names

• Ambrosia aptera DC.
• Ambrosia integrifolia Muhl. ex Willd.
• Ambrosia trifida f. integrifolia (Muhl. ex Willd.) Fernald
• Ambrosia trifida f. trifida
• Ambrosia trifida subsp. trifida
• Ambrosia trifida var. aptera (DC.) Kuntze
• Ambrosia trifida var. heterophylla Kuntze
• Ambrosia trifida var. integrifolia (Muhl. ex Willd.) Torr. & A.Gray
• Ambrosia trifida var. polyploidea J.Rousseau
• Ambrosia trifida var. texana Scheele
• Ambrosia trifida var. trifida

International Common Names

• English: blood ragweed; buffalo-weed; crownweed; great ragweed; horseweed
• Spanish: Artemisa grande
• French: ambroisie trifide; grande herbe à poux
• Chinese: san lie ye tun cao

Local Common Names

• Czech Republic: ambrozie trojklaná
• Estonia: kolmehõlmane ambroosia
• Finland: sormituoksukki
• Germany: Dreilappentraubenkraut; Dreilappige Ambrosie; Dreilappiges Traubenkraut; Dreispaltige Ambrosie
• Japan: kuwamodoki; oobutakusa
• Latvia: trisdaivu ambrozija
• Lithuania: triskiaute ambrozija
• Netherlands: driedeelige Ambrosia
• Norway: hesteambrosia
• Poland: ambrozja trójdzielna
• Slovakia: ambrózia trojzárezová
• Slovenia: trikrpata žvrklja
• Sweden: hästambrosia; tall Ambrosia
• USA: bitterweed; buffalo weed; horse-cane; horse-weed; kinghead; tall ragweed

EPPO code

• AMBTR (Ambrosia trifida)

Summary of Invasiveness

A. trifida is an annual herb native to temperate North America which is now present in a number of countries in Europe and Asia. The primary means of spread of A. trifida occurs accidentally as a contaminant of seed or agricultural equipment. This species readily colonises disturbed areas and is often one of the first plants to emerge in early spring. As a result it has an initial competitive advantage and can therefore behave as a dominant species throughout the entire growing season. A. trifida is a particular problem for cultivated agricultural and horticultural crops where it can significantly decrease yields. Like many species of Ambrosia, A. trifida produces pollen which is allergenic and can induce allergic rhinitis, fever, or dermatitis. A. trifida is extremely competitive and can also decrease native biodiversity. A. trifida is a declared noxious weed in its native range in California, Delaware, Illinois and New Jersey, USA and is also a quarantine weed in Poland and Russia.

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Dicotyledonae
•                     Order: Asterales
•                         Family: Asteraceae
•                             Genus: Ambrosia
•                                 Species: Ambrosia trifida

Notes on Taxonomy and Nomenclature

A. trifida was described by Linnaeus (1753: 988) as one of the four listed Ambrosia species (the other three species are: A. artemisiifolia L., A. elatior L., and A. maritima L.). The lectotype was designated by Reveal in Jarvis and Turland (1998: 351) on a specimen preserved at LINN (The Linnean Society, 2016)

According to USDA-NRCS (2016) two subspecies exist; A. trifida var. texana (Texan great ragweed) and A. trifida var. trifida (great ragweed). These subspecies have different distrubtions within North America, with A. trifida var. trifida being present in most states.

Description

A. trifida is an annual herb (therophyte), (30-)150-400 cm tall. Stems erect, branched or not. Leaves opposite, with blades rounded, deltate or elliptic [40-150(-250)×(10-)30-70(-200) mm], palmately 2-5-lobed, lobes with margins toothed, sparsely pubescent and glandular-dotted on both faces, petioled [petiole (10-)25-30(-70) mm long]. Flowers arranged in capitula, the male capitula forming a terminal leafless spike-like or raceme-like inflorescences at the end of the branches, the female capitula clustered at the base of the male inflorescences (pistillate flowers are tubular and without pappi); anthers yellow; ovary inferior with one ovule. Fruit (achene) pyramidal, (5-)6-12 mm long, brown to gray, glaborus or slightly pubescent, with 4-5 usually distal spines.

Distribution

A. trifida is found primarily in temperate areas around the world and is native to eastern North America; it is found throughout much of the USA and southern Canada. In Canada, this weed ranges from Nova Scotia westward to the Northwest Territory. Within the USA, it is most common in the mid-Atlantic states and the Ohio and Mississippi River valleys.

A. trifida is not currently present in Africa (CJB, 2016), South America or Australasia (Council of Heads of Australasian Herbaria, 2016).

Distribution Table

The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

History of Introduction and Spread

A. trifida is a neophyte which was introduced in Europe after the discovery of America. Detailed studies on the history of introduction however are not present. EPPO (2014) reports the year 1829 as the first date of introduction into Europe (Belgium), while concerning China, Qin et al. (2014) stated that this species was first introduced in 1935.

Introductions

Risk of Introduction

Further spread of A. trifida is highly likely, due to the risks of accidental movement seeds with agricultural equipment (locally) and as a contaminant of crop seeds. A. trifida is considered a noxious weed in many areas due to its intrusive nature and is a quarantine weed in Poland and Russia.

Habitat

A. trifida is most prevelant in disturbed sites such as, damp soils, wastelands, uncultivated and cultivated lands (field crops), garden, ditches, roadsides, field margins, constructions sites, etc. (Uva et al., 1997). It may also be found colonising riverbanks, pastures and grasslands (Abul-Fatih and Bazzaz, 1979; Megyeri, 2011). A. trifida is common in flood plains and rare in low rainfall areas.

Habitat List

Hosts/Species Affected

A. trifida is a weed of cultivated agronomic and horticultural crops such as species of Sorghum, Glycine max (soybean), Helianthus annuus (sunflower), Phaseolus spp (beans), Zea mays (maize), species of Triticum (wheat) and Gossypium hirsutum (cotton) (EPPO, 2014). It is extremely competitive and is especially difficult to control in many broadleaved crops. Experiments carried out by Baysinger and Sims (1991) in Missouri, USA, found that over two years dense populations of A. trifida reduced soybean seed yields by about 50%. A 55% reduction in corn yields in Michigan have also been recorded (Michigan State University, 2016).

Growth Stages

Biology and Ecology

Genetics

A. trifida is a taxon with 2n = 24, 48 (Strother, 2006). A hybrid was described with A. artemisiifolia (A. × helenae Rouleau) (Strother, 2006). Hybrids were found to have somatic chromosome numbers ranging from 2n = 27 to 2n = 33 (Bassett and Crompton, 1982).

Reproductive Biology

Each A. trifida plant can produce up to 10,300 seeds, while in soybeans and corn crops one plant can produce 1900-5500 seeds (Michigan State University, 2016). Pollination is mainly performed by wind, the pollen being small (20-30 µm), tricolporate, sphaerical, with 60-65 spines (Bassett and Crompton 1982). It has been estimated that one plant can produce 10 million pollen grains per day and one billion pollen grains during its lifetime (Johnson et al., 2007). The stigmas protrude and are receptive prior to the shedding of pollen in the male flowers (Bassett and Crompton, 1982).

Physiology and Phenology

In the native range in the USA, seeds generally begin to mature in mid-August (Uva et al., 1997). Most seeds fall near the parent plant, but some can disperse long distances with water, animals, and human activities. Most germination in the field occurs early to mid-spring and at soil depths to 16 cm, optimal 2 cm (Bassett and Crompton, 1982). Germination rarely occurs on the soil surface. Seedlings emerge in mid to late spring. Seedlings emerging from shallow depths are most likely to survive as they compete with other species for light. Mature seeds are usually dormant and require a cold, moist period to germinate. Seeds can germinate in a wide range of temperatures (8-41°C), but with an optimum range of 10-24°C (Abul-Fatih and Bazzaz, 1979).

Detailed study on seed germination of A. trifida by Abul-Fatih (1977) found that A. trifida usually produced seeds of various sizes. Large seed was able to germinate under relatively cold temperatures, a wide range of moisture regimes and soil depths. Small seed, which have smaller energy reserves, must germinate and establish rapidly during favourable periods if the seedling is to survive longer than other competing summer annuals.

A. trifida plants produce new stems and inflorescences when cut in late July and August.

Environmental Requirements

A. trifida occurs in a wide range of rainfall zones, but generally prefers moister soil with a summer rainfall regime. Mean monthly temperatures can range from 5°C to 30°C and it is fairly indifferent to soil types.

Climate

Air Temperature

Rainfall

Natural enemies

Notes on Natural Enemies

Leaf-spot diseases (Cercospora spp.) are common in the field in the USA, but rarely have significant impact on the competitiveness of A. trifida plants. In Louisiana, A. trifida is noted as a host of Papaipema nebris (Alvarado et al., 1989) and stem galls are caused by Protomyces gravidus (Holcomb, 1995).

A number of other natural enemies have been identified as A. trifida is the subject of a biological control programme. Potential agents include Euaresta bella, E. festiva (Batra, 1979), Zygogramma suturalis (Xie et al., 2000) and the pathogens Puccinia xanthii f.sp. ambrosid-trifidae and Pseudomonas syringae pv. tagetis (Batra, 1981).

Means of Movement and Dispersal

Natural Dispersal

A. trifida produces a large number of seeds which are dispersed by flood waters and with the wind.

Accidental Introduction

Seeds of A. trifida may accidentally be introduced into new areas with seeds or on cultivation and harvesting equipment.

Impact Summary

Economic Impact

A. trifida is a weed of cultivated agronomic and horticultural crops and as such it will compete for space and nutrients resulting in a decrease in crop yield (Xie et al., 2000). It is a particular problem in corn and soybean where 50% yield losses have been recorded (Weaver, 2003; Regnier et al., 2016). In addition, increased economic costs may result for the increased application of herbicides.

A positive impact may be seen with a noted decrease in the numbers of plant-parasitic nematodes found in soybean fields where A. trifida is present (Wang et al., 1998).

Environmental Impact

Impact on Biodiversity

A. trifida can behave as a dominant species throughout the entire growing season. It is often one of the first plants to emerge in early spring and as a result has an initial competitive advantage. It competes for resources (space, nutrients, light, water, etc.) with native species and as a result it may cause a decrease in biodiversity.

Social Impact

A. trifida produces pollens which have morphological characteristics which result in it being an aeroallergen causing rhinitis, fever, or dermatitis (D’Amato et al., 2007). The impact of this, compared to similar and more widespread Ambrosia species such as A. artemisiifolia, is much lower.

Risk and Impact Factors

• Invasive in its native range
• Proved invasive outside its native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Tolerant of shade
• Highly mobile locally
• Fast growing
• Has high reproductive potential
• Has propagules that can remain viable for more than one year

• Ecosystem change/ habitat alteration
• Increases vulnerability to invasions
• Negatively impacts agriculture
• Negatively impacts human health
• Negatively impacts animal health
• Reduced native biodiversity
• Threat to/ loss of native species

• Allelopathic
• Causes allergic responses
• Competition - monopolizing resources
• Induces hypersensitivity
• Rapid growth

• Highly likely to be transported internationally accidentally
• Difficult/costly to control

Uses

Social Benefit

A. trifida has little utility. The leaves have medicinal traditions that include its uses as an astringent, emetic, and febrifuge and it may be grown as an ornamental, but is not widely used for that purpose because of its unattractive flowers and rough, robust vegetative growth.

Similarities to Other Species/Conditions

A. trifida can be easily distinguished from the other annual species belonging to the genus Ambrosia by the leaves which are palmate, while in the other related taxa (A. bidentata, A. acanthicarpa, and A. artemisiifolia) the blades are pinnate. The flowering heads and fruit of A. artemisiifolia are similar but smaller than those of A. trifida. The leaves of A. artemisiifolia are usually twice divided and not 3-5 lobed, and the overall plant size is generally much smaller.

When a large number of the leaves of A. trifida are unlobed, it can appear similar to Xanthium strumarium or Helianthus annuus; however, the leaves of these species are mostly alternate, whereas those of A. trifida are opposite.

Prevention and Control

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Control

Mechanical Control

Tillage is effective for control of seedlings of A. trifida because of their early emergence in relation to many other summer annual weeds (tillage is less effective in populations where plants are larger). Under moist soil conditions, plants may be 'transplanted' and begin growing in another area. Hand-pulling can be effective for seedlings, especially in gardens and other small plots. Repeated mowing will effectively reduce seed production but will not eliminate A. trifida. If allowed to approach maturity it pays to hand-pull the weed, because the stout, woody stalks dull and break the blades of mowers and harvesters, and clog threshing machines. Control of A. trifida using electrical discharges proved to be good to excellent (Rasmusson et al., 1980).

Biological Control

Surveys of potential biocontrol agents of A. trifida began in California in 1967 (Goeden, 1978). Euaresta bella and E. festiva have been released in Russia from 1976 (Batra, 1979) but are not now known to have established (Julien and Griffiths, 1998). Puccinia xanthii forma specialis ambrosid-trifidae was found to be species-specific and a potential biocontrol agent (Batra, 1981). Limited research has been made on biological control with Zygogramma suturalis (Coleoptera: Chrysomelidae); introduced into China from Canada and the former USSR (Xie et al., 2000). The bacterial pathogen Pseudomonas syringae pv. tagetis is the causal agent of a disease characterized by apical chlorosis on several members of Asteraceae, and this potential biological control continues to be researched.

Biocontrol programmes are in place for a closely related Ambrosia species. Introductions of biological control agents have been made against A. artemisiifolia in Australia, China, Georgia, Russia and Yugoslavia and against A. pilyostachya in Kazakhstan and Russia (Julien and Griffiths, 1998). No doubt some of the successfully introduced agents also attacked A. trifida if it was present, as most the majority are specific only to the genus.

Chemical Control

Application of atrazine, chlorimuron, and imazaquin are effective pre-emergence herbicides for control of A. trifida. The post-emergence herbicides acifluorfen, bentazone, dicamba, glyphosate, imazethapyr and 2,4-D have been recommended (Weed Science Society of America, 2003).

Glyphosate will control plants up to six inches in height. Tank mixing 2,4-D with glyphosate is also useful in controling A. trifida. However, biotypes of A. trifida have been found to be resistant to ALS (acetolactate synthase)-inhibitor herbicides in the USA since 1998 (Weed Science Society of America, 2003).

Gaps in Knowledge/Research Needs

Further research is required to investigate the molecular differences between native vs. alien populations of A. trifida. In addition to this detailed phytosociological studies on non-native areas in which A. trifida is naturalized/invasive could be conducted.

References

Abul Fatih HA; Bazzaz FA, 1979. The biology of Ambrosia trifida L. II. Germination, emergence, growth and survival. New Phytologist, 83(3):817-827.

Abul-Fatih HA, 1977. PhD Thesis. University of Illinois at Urbana-Champaign, 145 pp.

Allard HA, 1943. The North American ragweeds and their occurrence in other parts of the world. Science, 98:292-294.

Alvarado LJ; Hogg DB; Wedberg JL, 1989. Effects of corn and selected weed species on feeding behaviour of the stalk borer, Papaipema nebris (Lepidoptera: Noctuidae). Great Lakes Entomologist, 22(2):65-69; 7 ref.

Bassett IJ; Crompton CW, 1982. The biology of Canadian weeds. 55. Ambrosia trifida L. Canadian Journal of Plant Science, 62(4):1003-1010.

Batra SWT, 1979. Reproductive behavior of Euaresta bella and E. festiva (Diptera: Tephritidae), potential agents for the biological control of adventive North American ragweeds (Ambrosia spp.) in Eurasia. Journal of the New York Entomological Society, 87(2):118-125.

Batra SWT, 1981. Puccinia xanthii forma specialis ambrosid-trifidae. A microcyclic rust for the biological control of giant ragweed, Ambrosia trifida (Compositae). Mycopathologia, 72(2):61-64

Baysinger JA; Sims BD, 1991. Giant ragweed (Ambrosia trifida) interference in soybeans (Glycine max). Weed Science, 39(3):358-362.

Biodiversity CRTC, 2003. National CDB Reports - Russia. ANNEX 3. List of quarantined harmful animals, illness of plants and weeds of Russian Federation. Kazakhstan.

CJB, 2016. African Plant Database. Conservatoire et Jardin Botaniques de la Ville de Geneve, Geneva, Switzerland, and South African National Biodiversity Institute, Pretoria, South Africa. Geneva, Switzerland: CJB/SANBI. http://www.ville-ge.ch/musinfo/bd/cjb/africa/

Council of Heads of Australasian Herbaria, 2016. Australia's Virtual Herbarium., Australia: Council of Heads of Australasian Herbaria. http://avh.ala.org.au

DAISIE, 2016. Delivering Alien Invasive Species Inventories for Europe. European Invasive Alien Species Gateway. www.europe-aliens.org/default.do

D'Amato G; Cecchi L; Bonini S; Nunes C; Annesi-Maesano I; Behrendt H; Liccardi G; Popov T; Cauwenberge Pvan, 2007. Allergenic pollen and pollen allergy in Europe. Allergy, 62(9):976-990. http://www.blackwell-synergy.com/loi/all

EPPO, 2014. PQR database. Paris, France: European and Mediterranean Plant Protection Organization. http://www.eppo.int/DATABASES/pqr/pqr.htm

Euro+Med, 2016. Euro+Med PlantBase - the information resource for Euro-Mediterranean plant diversity. http://www.emplantbase.org/home.html

Goeden RD, 1978. California as a source of natural enemies for the biological control of ragweeds. Proceedings of the 4th International Symposium on Biological Control of Weeds, Gainesville, 1976., 198

Gudzinskas Z, 1993. Genus Ambrosia L. (Asteraceae) in Lithuania. Thaiszia, 3(1):89-96

Holcomb GE, 1995. First report of Protomyces gravidus causing stem galls on giant ragweed in Louisiana. Plant Disease, 79(8):860.

Jarvis CE; Turland NJ, 1998. Typification of Linnaean specific and varietal names in the Compositae (Asteraceae). Taxon, 47(2):347-370.

Johnson B; Loux M; Nordby D; Sprague C; Nice G; Westhoven A; Stachler J, 2007. Biology and management of giant ragweed. The Glyphosate, Weeds, and Crops Series. West Lafayette, USA.

Julien MH; Griffiths MW, 1998. Biological Control of Weeds: a World Catalogue of Agents and their Target Weeds. Fourth Edition. Wallingford, UK: CAB International.

Karnkowski W, 2001. Can the weeds be recognized as quarantine pests? - Polish experiences with Ambrosia spp. Zbornik predavanj in referatov 5. Slovensko Posvetovanje o Varstvu Rastlin, C^hacek~atez^hacek~ ob Savi, Slovenija, 6. marec-8. marec 2001, 396-402; 21 ref.

Linnaeus C, 1753. Species Plantarum. Volume 2. Stockholm, Sweden: Laurentii Salvii, 639 pp.

Ma J; Liu Q, 2002. Flora of Beijing: An Overview and Suggestions for Future Research. Urban Habitats, 1(1):1-18.

Megyeri K, 2011. BSc Hons Thesis. Louisiana, USA: University of New Orleans, 48 pp.

Michigan State University, 2016. S-MSU Weed Science, Giant Ragweed (Ambrosia trifida L.). Michigan, USA: Michigan State University. http://www.msuweeds.com/worst-weeds/giant-ragweed

Mulligan GA, 2000. Common Weeds of the Northern United States and Canada. Ottawa, Canada: Agriculture Canada. http://members.rogers.com/mulligan4520/.

Qin Z; DiTommaso A; Wu RS; Huang HY, 2014. Potential distribution of two Ambrosia species in China under projected climate change. Weed Research (Oxford), 54(5):520-531. http://onlinelibrary.wiley.com/doi/10.1111/wre.12100/full

Rasmusson DD; Dexter AG; Warren H III, 1980. The use of electricity to control weeds. Proceedings North Central Weed Control Conference 1979, 34:66.

Regnier EE; Harrison SK; Loux MM; Holloman C; Ramarao Venkatesh; Diekmann F; Taylor R; Ford RA; Stoltenberg DE; Hartzler RG; Davis AS; Schutte BJ; Cardina J; Mahoney KJ; Johnson WG, 2016. Certified crop advisors' perceptions of giant ragweed (Ambrosia trifida) distribution, herbicide resistance, and management in the corn belt. Weed Science, 64(2):361-377. http://www.bioone.org/loi/wees

Royal Botanic Garden Edinburgh, 2003. Flora Europaea, Database of European Plants (ESFEDS). Edinburgh, UK: Royal Botanic Garden. http://rbg-web2.rbge.org.uk/FE/fe.html.

Shim SI; Lee SG; Kang BH, 1998. Effects of several chemicals and burial of seeds into the soil on dormancy-breaking of weed species. Korean Journal of Weed Science, 18(4):295-303.

Strother JL, 2006. Ambrosia L. Volume 8(3). Flora of North America North of México, 8(3).

The Linnean Society, 2016. The Linnean Collections. London, UK. http://linnean-online.org/

USDA-ARS, 2016. Germplasm Resources Information Network (GRIN). National Plant Germplasm System. Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

USDA-NRCS, 2016. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Uva RH; Neal JC; DiTomaso JM, 1997. Weeds of the Northeast. Ithaca, USA: Cornell University Press.

Wang Wei; Zhu XinRu; Liu WeiZhi, 1998. Influence of ragweed (Ambrosia trifida) on plant parasitic nematodes. Journal of Chemical Ecology, 24(10):1707-1714; 12 ref.

Weaver SE, 2003. Correlations among relative crop and weed growth stages. Weed Science, 51(2):163-170.

Weed Science Society of America, 2003. International Survey of Herbicide Resistant Weeds. HRAC/ NAHRAC/ WSSA. http://www.weedscience.org/in.asp.

Wu ZY; Raven PH; Hong DY, 2011. Flora of China Volumes 20-21 (Asteraceae). Beijing and St Louis, China and USA: Science Press and Missouri Botanical Garden Press, 353 pp.

Xie Yan; Li Zhenyu; Gregg WP; Li Dianmo, 2001. Invasive species in China - an overview. Biodiversity and Conservation, 10(8):1317-1341.

Yamazaki K; Imai C; Natuhara Y, 2000. Rapid population growth and food-plant exploitation pattern in an exotic leaf beetle, Ophraella communa LeSage (Coleoptera: Chrysomelidae), in western Japan. Applied Entomology and Zoology, 35(2):215-223; 30 ref.

Contributors

22/11/2016 Updated by:

Duilio Iamonico, University of Rome Sapienza, Rome, Italy

Distribution Maps