Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Amaranthus hybridus
(smooth pigweed)

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Datasheet

Amaranthus hybridus (smooth pigweed)

Summary

  • Last modified
  • 22 November 2019
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Host Plant
  • Preferred Scientific Name
  • Amaranthus hybridus
  • Preferred Common Name
  • smooth pigweed
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Dicotyledonae

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Pictures

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PictureTitleCaptionCopyright
Amaranthus hybridus (smooth pigweed); flowering habit.
TitleFlowering habit
CaptionAmaranthus hybridus (smooth pigweed); flowering habit.
Copyright©MarkusHagenlocher - CC BY-SA 3.0
Amaranthus hybridus (smooth pigweed); flowering habit.
Flowering habitAmaranthus hybridus (smooth pigweed); flowering habit.©MarkusHagenlocher - CC BY-SA 3.0

Identity

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Preferred Scientific Name

  • Amaranthus hybridus L. (1753)

Preferred Common Name

  • smooth pigweed

Other Scientific Names

  • Amaranthus chlorostachys Willd.
  • Amaranthus frumentaceus Buch.-Ham. ex Roxb.
  • Amaranthus incurvatus Timeroy ex Gren. & Godr.
  • Amaranthus patulus Bertol. (1837)

International Common Names

  • English: green amaranth; slim amaranth
  • Spanish: bledo; quelite
  • French: amarante hybride
  • Portuguese: caruru-de-folha-larga

Local Common Names

  • Brazil: caruru-branco; caruru-roxo
  • Germany: Bastard - Amarant; Gruenaehriger Amarant; Gruenaehriger Fuchsschwanz
  • Japan: honagaaogeito
  • Netherlands: basterdamarant

EPPO code

  • AMACH (Amaranthus hybridus)

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Dicotyledonae
  •                     Order: Caryophyllales
  •                         Family: Amaranthaceae
  •                             Genus: Amaranthus
  •                                 Species: Amaranthus hybridus

Notes on Taxonomy and Nomenclature

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A. hybridus has a chromosome number of 2n = 32 (Murray, 1940; Grant, 1959). It readily hybridizes with closely related species, but the F1 generation is highly sterile (Tucker and Sauer, 1958). Hybrids often have oddly shaped inflorescences. Brenan (1961) distinguished three subspecies of A. hybridus on the basis of the relative length of the bracts compared with the length of the sepals.

A. hybridus is sometimes confused with the cultivated species A. hypochondriacus and A. caudatus (love-lies-bleeding), both of which have long, thin often reddish inflorescences. However, Sauer (1967) contends that A. hypochondriacus was derived mainly from A. powellii, and A. caudatus mainly from A. quitensis. A. hybridus is thought to be the progenitor of A. cruentus, a cultivated grain and ornamental plant. Introgression has undoubtedly occurred among the weedy and domesticated amaranths. While this represents the current status of A. hybrudus in the strictest sense, it must be noted that the 'cultivated' A. cruentus often occurs as a weed and is sometimes referred to as 'A. hybridus' in weed literature. Hence it is likely that a number of the records in this data-sheet might refer more strictly to A. cruentus (or to other closely related species).

Description

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A. hybridus is an erect annual herbaceous plant which reproduces only by seeds. It produces a tap root and erect, often branched stems from 0.1 to 2.0 m in height. The stems are thick and often ribbed or tinged with red. Its leaves are alternate, long-stalked, and ovate to rhombic-ovate. Leaf and stem surfaces have small fine hairs. Flowers are numerous, green, and crowded into finger-like spikes forming a long, dense terminal panicle, with axillary spikes below. The terminal spike is often lax. Perianth segments 5, lanceolate, acute, 2–3 mm long, subtended by bracteoles somewhat longer, about 4 mm, with a long, sharp tip, causing the inflorescence to feel distinctly prickly. Stamens 5. At maturity, the entire plant may be reddish in colour. Seeds are round, dark brown, shiny, somewhat flattened, and 1.0 to 1.5 mm in diameter.

Distribution

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A. hybridus is a native riverbank pioneer of eastern North America and parts of Mexico, Central America and northern South America (Sauer, 1967). It is much more common in the eastern than the western half of the USA. Its range has expanded to Africa, south-central Asia and Australia, possibly because of its use as a green vegetable.

Distribution Table

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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.

Last updated: 25 Feb 2021
Continent/Country/Region Distribution Last Reported Origin First Reported Invasive Reference Notes

Africa

BotswanaPresent
Côte d'IvoirePresentOriginal citation: Hutchinson et al., 1954
EgyptPresent
EswatiniPresent
EthiopiaPresent, Widespread
GhanaPresentOriginal citation: Hutchinson et al., 1954
GuineaPresentOriginal citation: Hutchinson et al., 1954
KenyaPresent, Widespread
LesothoPresent
MalawiPresent
MaliPresentOriginal citation: Hutchinson et al., 1954
MoroccoPresent
MozambiquePresent
NamibiaPresent
NigeriaPresent
Sierra LeonePresentOriginal citation: Hutchinson et al., 1954
South AfricaPresent, Widespread
TanzaniaPresent, Widespread
UgandaPresent
ZambiaPresent, Widespread
ZimbabwePresent

Asia

BhutanPresent
IndiaPresent
-Andaman and Nicobar IslandsPresent
-PunjabPresent
IndonesiaPresent
JapanPresent
JordanPresent
LebanonPresent
PakistanPresent
South KoreaPresent
ThailandPresent, Widespread

Europe

AlbaniaPresent
AustriaPresent
BulgariaPresent
CzechiaPresent
Federal Republic of YugoslaviaPresent
FrancePresent
GermanyPresent
GreecePresent
HungaryPresent
ItalyPresent
PortugalPresent
-AzoresPresent
RomaniaPresent
RussiaPresent
SerbiaPresent
SpainPresent
-Balearic IslandsPresent
SwitzerlandPresent
United KingdomPresent

North America

CanadaPresent
-OntarioPresent
Costa RicaPresent
HondurasPresent
MexicoPresent, Widespread
United StatesPresent, Widespread
-ArkansasPresent
-CaliforniaPresent
-ColoradoPresent
-GeorgiaPresent
-HawaiiPresent
-IllinoisPresent
-KansasPresent
-KentuckyPresent
-MarylandPresent
-MississippiPresent
-New JerseyPresent
-New YorkPresent
-North CarolinaPresent
-PennsylvaniaPresent
-South CarolinaPresent
-TexasPresent
-VirginiaPresent
-WisconsinPresent

Oceania

AustraliaPresent
-New South WalesPresent
-Northern TerritoryPresent
-QueenslandPresent
-South AustraliaPresent
-TasmaniaPresent
-VictoriaPresent
-Western AustraliaPresent
New ZealandPresent, Widespread

South America

ArgentinaPresent, Widespread
BrazilPresent, Widespread
-Espirito SantoPresent
-GoiasPresent
-Mato Grosso do SulPresent
-Minas GeraisPresent
-ParanaPresent
-Rio Grande do SulPresent
-Santa CatarinaPresent
-Sao PauloPresent
ChilePresent
ColombiaPresent, Widespread
PeruPresent, Widespread
VenezuelaPresent

Habitat

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A. hybridus is found on a wide variety of soil types and textures. It is a common weed of cultivated fields, gardens, waste places, roadsides, riverbanks, and other open, disturbed habitats where annual weeds predominate. It is seldom found in closed or shaded communities (Weaver and McWilliams, 1980).

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial

Hosts/Species Affected

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A. hybridus is a common weed of many field and horticultural row crops throughout the temperate areas of the world.

Host Plants and Other Plants Affected

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Plant nameFamilyContextReferences
Beta vulgaris (beetroot)ChenopodiaceaeMain
    Capsicum (peppers)SolanaceaeOther
      Glycine max (soyabean)FabaceaeMain
        Gossypium (cotton)MalvaceaeMain
          Nicotiana tabacum (tobacco)SolanaceaeOther
            Phaseolus vulgaris (common bean)FabaceaeMain
              Pisum sativum (pea)FabaceaeOther
                Solanum tuberosum (potato)SolanaceaeOther
                  Sorghum bicolor (sorghum)PoaceaeMain
                    Triticum aestivum (wheat)PoaceaeOther
                      Zea mays (maize)PoaceaeMain

                        Biology and Ecology

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                        A. hybridus is a summer annual herbaceous weed that reproduces solely by seed with maximum emergence in late spring or early summer (Weaver and McWilliams, 1980; Anderson, 1994). Plants which emerge in late May generally begin to flower in late July or early August, and produce ripe seed by the beginning of September (Weaver, 1984). Its small seeds are easily dispersed by wind, and germinate primarily from the top 2 cm of soil in disturbed habitats. Germination is stimulated by light and/or high temperatures, with greatest germination occurring at alternating temperatures of 20/35°C in the light (Weaver and McWilliams, 1980; Weaver, 1984).

                        A. hybridus possesses the C4 pathway of photosynthesis, a low carbon dioxide compensation point, little photorespiration, and its optimum temperature for net photosynthesis lies between 30 and 40°C (Patterson, 1976). Separate male and female flowers occur on the inflorescence, and pollination is generally by wind. A single vigorous plant may produce as many as 100,000 seeds. Seed longevity has not been reported, but seeds of the closely related species A. retroflexus and A. powellii, can remain viable for many years when buried in soil.

                        Natural enemies

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                        Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
                        Albugo bliti Pathogen Leaves/Stems
                        Coleophora lineapuluella Herbivore Seeds
                        Coleophora versurella Herbivore Leaves
                        Contrachelus seniculus Herbivore Leaves
                        Erwinia rhapontici Pathogen Leaves
                        Herpetogramma bipunctalis Herbivore Leaves

                        Notes on Natural Enemies

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                        A. hybridus is a host plant for a variety of insect pests and diseases which attack crops, however damage is rarely severe enough to serve as biological control.

                        Impact

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                        A. hybridus is a principal weed in a variety of field and vegetable row crops, and has been reported to substantially reduce yields of maize, soyabeans, cotton, sugarbeet, sorghum and peas (Holm et al., 1977; Weaver and McWilliams, 1980). It can also reduce harvesting efficiency because of increased lodging of weed infested crops (Nave and Wax, 1971).

                        A. hybridus accumulates nitrates in its tissues and has caused poisoning of cattle (Ferreira et al., 1991).

                        A. hybridus is an alternative host for members of the parasitic nematode genus Meloidogyne and for tobacco mosaic virus (Holm et al., 1977; Tedford and Fortnum, 1988). It also serves as a host for Colletotrichum capsici, which causes anthracnose on tomato fruit and cotton seedlings (McLean and Roy, 1991).

                        Amaranthus species have been reported to cause allergic reactions in humans, primarily due to wind-borne pollen (Weber et al., 1978; Mitchell and Rook, 1979).

                        Uses

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                        A. hybridus has been reported to be a highly nutritious herbage and a potentially valuable forage crop (Mugerwa and Bwabye, 1974). It is used as a green vegetable in parts of South Africa, India, Mexico and the southern USA (Holm et al., 1977; Sealy et al., 1990). Hauptli and Jain (1978) suggested that it could be used as breeding material for recombining desirable yield characteristics in the cultivated grain amaranths.

                        Leaves and young seedlings are cooked like spinach and added to soups, etc. Leaves have a mild flavour. Seeds can be used raw or cooked as a cereal substitute. An astringent medical tea can be made from the leaves.

                        Uses List

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                        Animal feed, fodder, forage

                        • Fodder/animal feed

                        Genetic importance

                        • Related to

                        Human food and beverage

                        • Vegetable

                        Medicinal, pharmaceutical

                        • Traditional/folklore

                        Similarities to Other Species/Conditions

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                        A. hybridus is similar in appearance to A. retroflexus and A. powellii, particularly in the vegetative state. Flowering plants of A. retroflexus differ in having shorter, thicker branches on the terminal inflorescence, sepals rounded or blunt and often reflexed, bracteoles less distinctly spiny. A. powelli also has a somewhat thicker inflorescence, the bracteoles are longer (up to 6 mm), and stamens usually 3, not 5.

                        A. caudatus and A. hypochondriacus are ornamental, domesticated plants, with larger terminal inflorescences, often bright red in colour, with a utricle equalling or exceeding the bract and sepals in length. The utricle of A. hybridus, A. retroflexus, and A. powellii is shorter than the bracts and sepals. The seeds of the weedy amaranths are usually dark brown, whereas many forms of the cultivated grain amaranths have ivory seeds.

                        Many other Amaranthus species are superficially similar. Of those included as data-sheets in this compendium, A. spinosus has spines, A. viridis has much smaller flowers, A. bitum has indented leaf tips, and A graecizans and A. blitoides have axillary inflorescences. Further species can occur as weeds on a local basis and reference to local floras is therefore recommended.

                        Prevention and Control

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                        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.

                        Cultural Control

                        Seedlings of A. hybridus can be controlled by cultivation, but older plants often recover from mechanical damage by producing axillary branches and inflorescences.

                        Chemical Control

                        A. hybridus is readily controlled by almost all the standard soil-applied and foliar-applied herbicides used for controling broadleaved weeds, including atrazine, simazine, metribuzin, linuron, bromoxynil, 2,4-D, dicamba, imazethapyr, thifensulfuron-methyl, rimsulfuron, nicosulfuron, acifluorfen, fomesafen and pendimethalin (Weaver and McWilliams, 1980; Manley et al., 1996; Robinson et al., 1996). Its pattern of intermittent germination throughout the growing season, however, make the application of residual soil-applied herbicides, or sequential post-emergence treatments, necessary in heavily infested fields. Lorenzi (1984) indicates that A. hybridus is only moderately susceptible to oxyfluorfen, butylate or vernolate.

                        Populations of A. hybridus resistant to triazine herbicides have been reported in the USA, France, Switzerland, Italy, Spain, Israel and South Africa (Heap, 1997). Populations resistant to the imidazolinone herbicides have been found in the USA (Heap, 1997).

                        Biological Control

                        Reputed biological control agents for A. hybridus are the pathogenic bacterium, Erwinia carotovora var. rhapontici [Erwinia rhapontici], (Gonzalez-Mendoza and Rodriguez, 1990), and insects Herpetogramma bipunctalis and Conotrachelus seniculus (Perez Panduro et al., 1990), all in Mexico.

                        References

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                        Abu-Irmaileh BE, 1982. Weeds of Jordan. Amman, Jordan: University of Jordan.

                        Aellen P, Akeroyd JR, 1993. Amaranthus L. In: Tutin TG, Burges NA, Chater AO, Edmondson JR, Heywood VH, Moore DM, Valentine DH, Walters SM, Webb DA, eds. Flora Europaea. Volume 1. Psilotaceae to Platanaceae. 2nd edition. Cambridge, UK: Cambridge University Press, 130-132.

                        Anderson RL, 1994. Characterizing weed community seedling emergence for a semiarid site in Colorado. Weed Technology, 8(2):245-249; 32 ref.

                        Birschbach ED, Myers MG, Harvey RG, 1993. Triazine-resistant smooth pigweed (Amaranthus hybridus) control in field corn (Zea mays L.). Weed Technology, 7(2):431-436

                        Brenan JPM, 1961. Amaranthus in Britain. Watsonia, 4:261-280.

                        Cavero J, Zaragoza C, Gil Ortega R, 1996. Tolerance of direct-seeded pepper (Capsicum annuum) under plastic mulch to herbicides. Weed Technology, 10(4):900-906; 26 ref.

                        Chaisattapagon C, Zhang NQ, 1992. Identifying effective criteria for weed detection using machine vision. Paper - American Society of Agricultural Engineers, No. 92-3576.

                        Chirila C, Pintilie C, 1985. The principal weeds and their control (XVIII). Wild pigweed (Amaranthus retroflexus L.), field pigweed (Amaranthus hybridus L.) and creeping pigweed (Amaranthus blitoides S. Wats.). Productia Vegetala, Cereale si Plante Tehnice, 37(7):28-31

                        Dagar JC, Gangwar B, Sharma AK, 1991. Distribution and integrated management of weeds in Bay Islands. Journal of the Andaman Science Association, 7(1-2):31-52.

                        Ferreira JLM, Riet-Correa F, Schild AL, Méndez MDC, 1991. Poisoning of cattle by Amaranthus spp. (Amaranthaceae) in Rio Grande de Sul, southern Brazil. Pesquisa Veterinária Brasileira, 11(3/4):49-54; 22 ref.

                        Gonzalez Mendoza L, Rodriguez MM de L, 1990. Isolation, identification and pathogenicity of bacteria of Amaranthus hybridus L. and possibilities of their biological control. Revista Chapingo, 15:67-68.

                        Graham PL, Steiner JL, Wiese AF, 1988. Light absorption and competition in mixed sorghum-pigweed communities. Agronomy Journal, 80(3):415-418

                        Grant WF, 1959. Cytogenetic studies in Amaranthus. III. Chromosome numbers and phylogenetic aspects. Canadian Journal of Genetics and Cytology, 1:313-328.

                        Hartzler RG, Roth GW, 1993. Effect of prior year's weed control on herbicide effectiveness in corn (Zea mays). Weed Technology, 7(3):611-614; 7 ref.

                        Hauptli H, Jain SK, 1978. Biosystematics and agronomic potential of some weedy and cultivated amaranths. Theoretical and Applied Genetics, 52(4):177-185

                        Heap IM, 1997. International Survey of Herbicide-Resistant Weeds. Annual Report, Weed Science Society of America.

                        Holm LG, Pancho JV, Herberger JP, Plucknett DL, 1991. A Geographic Atlas of World Weeds. Malabar, Florida, USA: Krieger Publishing Company.

                        Holm LG, Plucknett DL, Pancho JV, Herberger JP, 1977. The World's Worst Weeds. Distribution and Biology. Honolulu, Hawaii, USA: University Press of Hawaii.

                        Hutchinson J, Dalziel JM, 1954. Flora of West Tropical Africa, Volume 1, Part 1 (revised by Keay RWJ). London, UK: Crown Agents.

                        Jordan N, 1996. Effects of the triazine-resistance mutation on fitness in Amaranthus hybridus (smooth pigweed). Journal of Applied Ecology, 33(1):141-150; 32 ref.

                        Lazarides M, Cowley K, Hohnen P, 1997. CSIRO handbook of Australian weeds. CSIRO handbook of Australian weeds., vii + 264 pp.

                        Lorenzi H, 1982. Weeds of Brazil, terrestrial and aquatic, parasitic, poisonous and medicinal. (Plantas daninhas de Brasil, terrestres, aquaticas, parasitas, toxicas e medicinais.) Nova Odessa, Brazil: H. Lorenzi, 425 pp.

                        Lorenzi H, 1984. Manual de Identificacao e Controle de Plantas Danhinas. Odessa, Brazil: H. Lorenzi.

                        Lorenzi HJ, Jeffery LS(Editors), 1987. Weeds of the United States and their control. New York, USA; Van Nostrand Reinhold Co. Ltd., 355 pp.

                        Lugo Mde L, Gonzßlez A, Talbert RE, 1995. Smooth pigweed (Amaranthus hybrid[u]s L.) interference with snap bean (Phaseolus vulgaris L.) quality. Journal of Agriculture of the University of Puerto Rico, 79(3-4):173-179; 6 ref.

                        Majek BA, Neary PE, Polk DF, 1993. Smooth pigweed interference in newly planted peach trees. Journal of Production Agriculture, 6(2):244-246

                        Mamarot J, Rodriguez A, 1997. Sensibilité des Mauvaises Herbes aux Herbicides. 4th edition. Paris, France: Association de Coordination Technique Agricole.

                        Manley BS, Wilson HP, Hines TE, 1996. Smooth pigweed (Amaranthus hybridus) and livid amaranth (A. lividus) response to several imidazolinone and sulfonylurea herbicides. Weed Technology, 10(4):835-841; 22 ref.

                        McLean KS, Roy KW, 1991. Weeds as a source of Colletotrichum capsici causing anthracnose on tomato fruit and cotton seedlings. Canadian Journal of Plant Pathology, 13(2):131-134

                        Mitchell J, Rook A, 1979. Botanical Dermatology: plants and plant products injurious to the skin. Vancouver, Canada: Greengrass.

                        Morros ME, Trujillo B, Ponce M, 1990. Description of the genus Amaranthus L. with 3 new records for Venezuela and a key for the species. Ernstia, 58-59-60:45-51

                        Mugerwa JS, Bwabye R, 1974. Yield, composition and in vitro digestibility of Amaranthus hybridus subspecies incurvatus. Tropical Grasslands, 8:49-53.

                        Murray MJ, 1940. The genetics of sex determination in the family Amaranthaceae. Genetics, 25:409-431.

                        Nave WR, Wax LM, 1971. Effect of weeds on soybean yield and harvesting efficiency. Weed Science, 19:533-535.

                        Oyelola O, Banjoko I, Ajishin I, 2014. Nutritional content of common Amaranthus hybridus vegetable (Efo Tete) in Nigeria (828.4), The FASEB Journal, 28(1)

                        Parker C, 1992. Weeds of Bhutan. Weeds of Bhutan., vi + 236 pp.

                        Patterson DT, 1976. C4 photosynthesis in smooth pigweed [Amaranthus hybridus]. Weed Science, 24(1):127-130

                        Perez Panduro A, Solis Aguilar JF, Trujillo Arriaga J, Romero Rosales F, 1990. Biological agents for population regulation of Tithonia tubaeformis (Jacq) Cass (Asteraceae), Amaranthus hybridus L. and A. spinosus L. (Amaranthaceae) in Chapingo, State of Mexico and Tecalitlan, Jalisco. Revista Chapingo, 15(67-68):126-129

                        Portillo HE, Pitre HN, Meckenstock DH, Andrews KL, 1996. Oviposition preference of Spodoptera latifascia (Lepidoptera: Noctuidae) for sorghum, maize and non-crop vegetation. Florida Entomologist, 79(4):552-562; 25 ref.

                        Queir=s M, 1989. Cytotaxonomic studies of Amaranthus in Portugal. Lazaroa, 11:9-17; 63 ref.

                        Rambakudzibga AM, 1991. Allelopathic effects of aqueous wheat (Triticum aestivum L.) straw extracts on the germination of eight arable weeds commonly found in Zimbabwe. Zimbabwe Journal of Agricultural Research, 29(1):77-79.

                        Robinson DK, Monks DW, Monaco TJ, 1996. Potato (Solanum tuberosum) tolerance and susceptibility of eight weeds to rimsulfuron with and without metribuzin. Weed Technology, 10(1):29-34; 11 ref.

                        Salas CA, 1985. Wheat in Costa Rica. Wheats for more tropical environments. A proceedings of the international symposium Mexico City, Mexico: CIMMYT, 46-50.

                        Sauer JD, 1967. The grain amaranths and their relatives: A revised taxonomic and geographic survey. Annals of the Missouri Botanic Garden, 54:103-137.

                        Scott JE, Weston LA, Jones RT, 1995. Clomazone for weed control in transplanted cole crops (Brassica oleracea). Weed Science, 43(1):121-127

                        Sealy RL, McWilliams EL, Novak J, Fong F, Kenerley CM, Simon JE, 1990. Vegetable amaranths: cultivar selection for summer production in the south. In: Janick J, ed. Advances in new crops. Proceedings of the First National Symposium 'New Crops: Research, Development, Economics', Indianapolis, USA. Oregon, USA: Timber Press, 396-398.

                        Senesac AF, 1985. Aspects of the biology and control of pigweed (Amaranthus spp.) in New York. Dissertation Abstracts International, B (Sciences and Engineering), 46(4):1007B

                        Simpson DM, Stoller EW, 1995. Response of sulfonylurea-tolerant soybean (Glycine max) and selected weed species to imazethapyr and thifensulfuron combinations. Weed Technology, 9(3):582-586

                        Tackholm V, 1974. Students' Flora of Egypt. 2nd edition. Cairo, Egypt: University of Cairo.

                        Tedford EC, Fortnum BA, 1988. Weed hosts of Meloidogyne arenaria and M. incognita common in tobacco fields in South Carolina. Annals of Applied Nematology, 2:102-105.

                        Townsend CC, 1985. Amaranthaceae. In: Polhill RM, ed. Flora of Tropical East Africa. Rotterdam, Netherlands: A.A. Balkema, 1-2, 20-24, 35-36.

                        Townsend CC, 1988. Amaranthaceae. In: Launert E, ed. Flora Zambesiaca. Volume 9, Part 1. London, UK: Flora Zambesiaca Management Committee, 28-133.

                        Tucker JM, Sauer JD, 1958. Aberrant Amaranthus populations of the Sacramento-San Joaquin Delta, California. Madrono, 14:252-261.

                        Vencill WK, Banks PA, 1994. Effects of tillage systems and weed management on weed populations in grain sorghum (Sorghum bicolor). Weed Science, 42(4):541-547

                        Weaver SE, 1984. Differential growth and competitive ability of Amaranthus retroflexus, A. powellii and A. hybridus. Canadian Journal of Plant Science, 64(3):715-724

                        Weaver SE, McWilliams EL, 1980. The biology of Canadian weeds. 44. Amaranthus retroflexus L., A. powellii S. Wats. and A. hybridus L. Canadian Journal of Plant Science, 60(4):1215-1234

                        Weber RW, Mansfield LE, Nelson HS, 1978. Cross-reactivity among weeds of the amaranth and chenopod families. Journal of Allergy and Clinical Immunology, 61:172.

                        Wells MJ, Balsinhas AA, Joffe H, Engelbrecht VM, Harding G, Stirton CH, 1986. A catalogue of problem plants in South Africa. Memoirs of the botanical survey of South Africa No 53. Pretoria, South Africa: Botanical Research Institute.

                        Yenish JP, Worsham AD, York AC, 1996. Cover crops for herbicide replacement in no-tillage corn (Zea mays). Weed Technology, 10(4):815-821; 19 ref.

                        Distribution References

                        Abu-Irmaileh B E, 1982. Weeds of Jordan (weeds of crop fields). Amman University, Jordan: Jordan. 433pp.

                        Aellen P, Akeroyd JR, 1993. Amaranthus L. In: Flora Europaea. Volume 1. Psilotaceae to Platanaceae, Volume 1 (2nd edition) [ed. by Tutin TG, Burges NA, Chater AO, Edmondson JR, Heywood VH, Moore DM, Valentine DH, Walters SM, Webb DA]. Cambridge, UK: Cambridge University Press. 130-132.

                        Anderson R L, 1994. Characterizing weed community seedling emergence for a semiarid site in Colorado. Weed Technology. 8 (2), 245-249.

                        Anon, 1987. Weeds of the United States and their control. [ed. by Lorenzi H J, Jeffery L S]. New York, USA: Van Nostrand Reinhold Co. Ltd. 355 pp.

                        Ávila-Alistac N, Ramírez-Rojas S, Lozoya-Saldaña H, Rebollar-Alviter Á, Guzmán-Plazola R A, 2017. Alternate hosts of Iris yellow spot virus and trips on onion crops in Morelos and Michoacan, Mexico. Revista Mexicana de Fitopatología. 35 (2), 242-262. http://www.rmf.smf.org.mx/Vol3522017/RMF_Vol_35_2_2017.pdf

                        Birschbach E D, Myers M G, Harvey R G, 1993. Triazine-resistant smooth pigweed (Amaranthus hybridus) control in field corn (Zea mays L.). Weed Technology. 7 (2), 431-436.

                        CABI, Undated. Compendium record. Wallingford, UK: CABI

                        CABI, Undated a. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

                        Cavero J, Zaragoza C, Gil Ortega R, 1996. Tolerance of direct-seeded pepper (Capsicum annuum) under plastic mulch to herbicides. Weed Technology. 10 (4), 900-906.

                        Chaisattapagon C, Zhang N Q, 1992. Identifying effective criteria for weed detection using machine vision. In: Paper - American Society of Agricultural Engineers, 19 pp.

                        Chirilă C, Pintilie C, 1985. The principal weeds and their control (XVIII). Wild pigweed (Amaranthus retroflexus L.), field pigweed (Amaranthus hybridus L.) and creeping pigweed (Amaranthus blitoides S. Wats.). (Principaele buruieni și combaterea lor (XVIII). Știrul sălbatic (Amaranthus retroflexus L.), știrul de ogoare (Amaranthus hybridus L.) și știrul tîrîtor (Amaranthus blitoides S. Wats.).). Producția Vegetală, Cereale și Plante Tehnice. 37 (7), 28-31.

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