Polygonum aviculare (prostrate knotweed)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Habitat List
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Polygonum aviculare L. (1753)
Preferred Common Name
- prostrate knotweed
Other Scientific Names
- Polygonum aviculare L. subsp. rectum Chrtek 1956
- Polygonum aviculare subsp. aequale (Lindm.) Aschers. et Graebn.
- Polygonum aviculare subsp. depressum (Meisn.) Arcang.
- Polygonum aviculare subsp. microspermum (Jord. ex Boreau) Berher
- Polygonum aviculare subsp. monspeliense (Thiéb.) Chrtek 1956
- Polygonum erectum Roth. 1783
- Polygonum heterophyllum Lindman 1912
- Polygonum monspeliense Thiébaud in Persoon 1805
- Polygonum rectum (Chrtek) Scholz 1959
International Common Names
- English: hogweed; ironweed; knotgrass; knotweed; wireweed
- Spanish: ciennudos; huichun; sangrina; sanguinaria
- French: renouée des oiseaux; traînasse
- Portuguese: cemtinodia; erva muda; sanguinha; sempre noiva
Local Common Names
- Algeria: gerda
- Argentina: chilillo; cien nudos; pasto chanchero
- Belgium: varkensgras
- Brazil: sempre noiva dos passarinhos
- Chile: pasto del pollo
- Colombia: caminadora; ciennudos; gonorrea
- Denmark: honsegraes; vej-pileurt
- Ecuador: coloradilla
- Egypt: qoddaad; qordaab
- Finland: pihatatar
- France: centinode; herbe aux cochons
- Germany: Blutkraut wegetritt; Vogel-Knöterich
- Guatemala: corredora; hierba de chivo
- Hungary: madar keserufu
- Iceland: blooarfi; hlaoarfi
- Iran: khorfe
- Iraq: massalah
- Italy: centinoda; corregiola
- Japan: michi-yanagi; niwayanagi
- Lebanon: assa-er-rai; batbat; door weed; shabat al ghul
- Madagascar: ahitrakely
- Mexico: alambrillo; huichuri; verdolaga
- Netherlands: varkensgras
- Norway: tungras
- Paraguay: correguela
- Poland: rdest ptasi; wróble jezyczki
- Saudi Arabia: batbat; shabat el ghul; turnah
- Slovakia: rdesno ptaci
- South Africa: koperdraadgras; voeduisendknoop
- Spain: cien nudos; correguela de los caminos; herbe de las calenturas; lengue de pajaro; sanguinaria mayor
- Sweden: tramport; tranpgras
- Turkey: coban degnegi
- Yugoslavia (Serbia and Montenegro): dvornik oputina; dvornik pticji; pticja dresen; tro skot
- POLAR (Polygonum arenastrum)
- POLAV (Polygonum aviculare)
- POLER (Polygonum erectum)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Spermatophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Polygonales
- Family: Polygonaceae
- Genus: Polygonum
- Species: Polygonum aviculare
Notes on Taxonomy and NomenclatureTop of page The name Polygonum aviculare has been used in two different ways. In a broad sense, it refers to a very polymorphic aggregate in which a large number of 'microspecies' have been recognized. In a narrower sense, it refers to one of the segregate taxa (= P. heterophyllum, P. monspeliense). There appears to be no consensus as to the number of subordinate taxa or as to the taxonomic level at which these should be recognized.
Besides P. aviculare sensu stricto, the best defined and most widely accepted segregate is P. arenastrum (= Polygonum aequale, P. aviculare L. subsp. aequale, P. aviculare L. subsp. depressum (which is treated as a discrete species in many standard floras (for example, Webb and Chater, 1993). See Similarities to Other Species for distinguishing characters between P. aviculare sensu stricto and P. arenastrum. For thorough taxonomic and nomenclatural discussions, see for example, McNeill (1981a, 1981b) and Schmid (1983). However, in many citations from the agronomic literature, it is not clear whether the name P. aviculare is used in the broad or the narrow sense as defined above. For instance, the illustration and description of P. aviculare in Holm et al. (1997) is most likely pertain to P. arenastrum. As P. arenastrum and P. aviculare sensu stricto are usually not distinguished in ecological and geographical surveys, their respective distribution and ecological preferences, especially in cultivated fields, are not fully elucidated.
P. aviculare, even defined in the narrower sense, is a polyploid complex with tetraploid (2n = 40) and hexaploid (2n = 60) lines, the former cytotype being less frequent than the latter (Wolf and McNeill, 1987; Meerts et al., 1998). Both cytotypes can form mixed populations in agricultural areas (Meerts, 1992; Meerts et al., 1998).
P. plebejum is a diploid member of the P. aviculare aggregate that is worthy of recognition in view of its distinct geographical distribution (See Similarities to Other Species).
DescriptionTop of page Glabrous annual. Stems ascending or prostrate, longitudinally ribbed, often much branched, 5-70 (-150) cm long, internodes 5-60 mm long; leaves numerous, elliptical to lanceolate-linear, those on the main stems often noticeably larger than those of the branches, (5-) 15-40 (-60) mm long, 2-12 (-20) mm wide, green to grey green, sometimes glaucous, entire, obscurely nerved, top acute to rounded, base gradually narrowing into a short petiole, or leaf subsessile; ocreae 5-9 mm long, irregularly lacerate, silvery-membranous. Flowers solitary or in groups of two to seven in the axils of most, except lowermost, leaves, pedicels very short; perianth whitish or pink with a greenish base, 2.4-4 mm long; tepals five, obtuse or rounded at apex, fused at base; stamens (5-)8. Achene ovate, usually triquetrous, 2.0-3.5 mm long, 1.3-2.3 mm wide, dark brown to black, dull (rarely shiny).
Hypocotyl 1-5 cm; two cotyledons, glabrous, often somewhat fleshy, green to glaucous-green, linear to very narrowly oblong-linear, 5-20 mm long, 1-2 mm wide, with obtuse to rounded tip, base gradually tapering into indistinct petiole; first leaf oblanceolate to narrowly elliptical, glabrous, entire, 10-20 mm long, 4-8 mm wide, often with margins downwards inrolled, base sheathed by membranous hyaline ocrea.
DistributionTop of page P. aviculare is native to Europe, but has been extensively introduced elsewhere. It is now a widespread weed in nearly all the temperate regions of the world and, more locally, in warmer climates. Its range may still be extending. Its extension towards equatorial regions could be restrained by chilling requirements.
Distribution TableTop of page
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.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Afghanistan||Present, few occurrences||Holm et al., 1979|
|Armenia||Present||Holm et al., 1997|
|Bangladesh||Present||Holm et al., 1997|
|China||Widespread||Holm et al., 1979; Wang, 1990|
|-Gansu||Present||Zhang et al., 1992|
|-Heilongjiang||Present||Holm et al., 1997|
|-Jiangsu||Present||Hu et al., 1989|
|India||Present||Present based on regional distribution.|
|-Jammu and Kashmir||Present||Holm et al., 1997|
|Iran||Widespread||Holm et al., 1979; Mosaferi et al., 2015|
|Iraq||Widespread||Holm et al., 1979|
|Israel||Present||Holm et al., 1979|
|Japan||Widespread||Namuta & Yoshikawa, 1975; Holm et al., 1979|
|-Honshu||Widespread||Holm et al., 1997|
|Korea, DPR||Present, few occurrences||Holm et al., 1979|
|Korea, Republic of||Present, few occurrences||Holm et al., 1979|
|Kyrgyzstan||Present||Holm et al., 1997|
|Lebanon||Present||Holm et al., 1979|
|Mongolia||Present||Holm et al., 1997|
|Nepal||Present||Holm et al., 1979|
|Pakistan||Present||Holm et al., 1979|
|Saudi Arabia||Present||Holm et al., 1997|
|Turkey||Present||Holm et al., 1979; Tepe et al., 1994|
|Uzbekistan||Present||Rakhimberdyeva and Shodiev, 1989|
|Botswana||Present||Wells et al., 1986|
|Egypt||Present||Holm et al., 1979|
|Ethiopia||Widespread||Holm et al., 1979|
|Kenya||Widespread||Holm et al., 1979|
|Lesotho||Present||Holm et al., 1997|
|Madagascar||Present||Holm et al., 1997|
|Mali||Present||Holm et al., 1997|
|Morocco||Present||Holm et al., 1979|
|Namibia||Present||Wells et al., 1986|
|South Africa||Widespread||Holm et al., 1979; Wells et al., 1986|
|Tunisia||Widespread||Holm et al., 1979|
|Zimbabwe||Present||Holm et al., 1979|
|Canada||Widespread||Holm et al., 1979|
|-Alberta||Present||Mertens and Raven, 1965|
|-British Columbia||Present||Mertens and Raven, 1965|
|-Newfoundland and Labrador||Present||McNeill, 1981a|
|-Nova Scotia||Present||McNeill, 1981a|
|-Ontario||Present||Wolf and McNeill, 1987|
|-Saskatchewan||Present||Holm et al., 1997|
|-Yukon Territory||Present||Mertens and Raven, 1965|
|Mexico||Widespread||Holm et al., 1997|
|USA||Widespread||Holm et al., 1979; Wells et al., 1986|
|-Alaska||Widespread||Holm et al., 1979|
|-Georgia||Widespread||Johnson and Murphy, 1989|
|-Idaho||Present||Mertens and Raven, 1965|
|-Indiana||Present||Savage and Mertens, 1968|
|-Mississippi||Widespread||Shaw and Rainero, 1990|
|-Nevada||Present||Mertens and Raven, 1965|
|-New Mexico||Present||Anderson and Hoxworth, 1985|
|-New York||Present||Stalter and Kincaid, 1986|
|-Oregon||Widespread||Crabtree and Westwood, 1976|
|-Rhode Island||Widespread||Ebdon and Jagschitz, 1982|
|-Wisconsin||Present||Savage and Mertens, 1968|
|-Wyoming||Widespread||Alley and Humburg, 1978|
Central America and Caribbean
|El Salvador||Present||Holm et al., 1979|
|Honduras||Widespread||Holm et al., 1979|
|Argentina||Widespread||Holm et al., 1979|
|Bolivia||Widespread||Holm et al., 1997|
|Brazil||Widespread||Holm et al., 1979|
|Chile||Widespread||Holm et al., 1979|
|Colombia||Widespread||Holm et al., 1979|
|Ecuador||Widespread||Holm et al., 1997|
|Peru||Widespread||Holm et al., 1979|
|Uruguay||Widespread||Holm et al., 1979; Holm et al., 1997|
|Albania||Present||Jalas and Suominen, 1979|
|Austria||Widespread||Holm et al., 1979|
|Belarus||Present||Jalas and Suominen, 1979|
|Belgium||Widespread||Holm et al., 1979|
|Bosnia-Hercegovina||Present||Jalas and Suominen, 1979|
|Bulgaria||Widespread||Dechkov, 1989; Holm et al., 1997|
|Croatia||Present||Jalas and Suominen, 1979|
|Czech Republic||Present||Jalas and Suominen, 1979|
|Czechoslovakia (former)||Widespread||Jalas and Suominen, 1979; Kovacs, 1988|
|Denmark||Widespread||Andreasen et al., 1996; Holm et al., 1997|
|Estonia||Present||Jalas and Suominen, 1979|
|Finland||Widespread||Holm et al., 1979|
|France||Widespread||Holm et al., 1979|
|-Corsica||Present||Jalas and Suominen, 1979|
|Germany||Widespread||Holm et al., 1979|
|Greece||Present||Holm et al., 1979|
|Hungary||Widespread||Holm et al., 1979|
|Iceland||Widespread||Holm et al., 1979|
|Ireland||Widespread||Mitchell, 1986; Holm et al., 1997|
|Italy||Widespread||Holm et al., 1979|
|Latvia||Present||Jalas and Suominen, 1979|
|Lithuania||Present||Jalas and Suominen, 1979|
|Luxembourg||Present||Jalas and Suominen, 1979|
|Macedonia||Present||Jalas and Suominen, 1979|
|Malta||Present||Jalas and Suominen, 1979|
|Moldova||Present||Jalas and Suominen, 1979|
|Netherlands||Widespread||Holm et al., 1979|
|Norway||Widespread||Holm et al., 1979|
|Poland||Widespread||Holm et al., 1979|
|Portugal||Widespread||Holm et al., 1979; Monteiro et al., 1995|
|-Azores||Present||Jalas and Suominen, 1979|
|-Madeira||Present||Jalas and Suominen, 1979|
|Romania||Widespread||Holm et al., 1979|
|Russian Federation||Widespread||Holm et al., 1979|
|-Central Russia||Present||Jalas and Suominen, 1979|
|-Northern Russia||Present||Jalas and Suominen, 1979|
|-Russian Far East||Present||Holm et al., 1997|
|-Southern Russia||Present||Jalas and Suominen, 1979|
|-Western Siberia||Present||Holm et al., 1997|
|Slovakia||Present||Jalas and Suominen, 1979|
|Slovenia||Present||Jalas and Suominen, 1979|
|Spain||Widespread||Holm et al., 1979|
|-Balearic Islands||Present||Jalas and Suominen, 1979|
|Sweden||Widespread||Holm et al., 1979|
|Switzerland||Present||Jalas and Suominen, 1979; Holm et al., 1997|
|UK||Widespread||Holm et al., 1979|
|Yugoslavia (former)||Widespread||Holm et al., 1979|
|Yugoslavia (Serbia and Montenegro)||Widespread||Holm et al., 1979|
|Australia||Widespread||Holm et al., 1979|
|-Australian Northern Territory||Present||Holm et al., 1979|
|-New South Wales||Widespread||Lemerle et al., 1996; Holm et al., 1997|
|-Queensland||Present||Holm et al., 1997|
|-South Australia||Present||Holm et al., 1997|
|-Tasmania||Widespread||Holm et al., 1997; Macleod, 1997|
|-Victoria||Widespread||Amor and Francisco, 1987|
|-Western Australia||Present||Holm et al., 1997|
|New Zealand||Widespread||Holm et al., 1979|
|Solomon Islands||Present||Holm et al., 1997|
HabitatTop of page P. aviculare has a very wide ecological amplitude with respect to soil texture, reaction and humidity. However, it is largely restricted to sites of pH >5.0 (Grime et al., 1988). It is favoured by soil compaction and heavy nitrogen fertilization, but tolerates drought and low nutrient fertility (Grime et al., 1988). In climates with a marked dry season, it is usually restricted to irrigated crops. P. aviculare (or at least some of its varieties) is extremely resistant to trampling and is a frequent component of the flora of cart-tracks; accordingly, it can spread in agricultural areas damaged by vehicles and implements (Kress, 1988).
P. plebejum prefers moist soils, being particularly frequent along irrigation ditches (Pandey et al., 1995) and in low lying areas such as temporary ponds and pools (Sant and Kamlesh, 1979).
Habitat ListTop of page
Hosts/Species AffectedTop of page P. aviculare is typically a weed of spring crops (Tottman and Wilson, 1990). It is one of the relatively few weeds that are equally abundant in both cereals and broad-leaved crops and is a principal or serious weed of a wide range of crops in temperate climates (Holm et al., 1997). It is also a principal weed of specific warm climate crops, including soyabean, sweet potato, cotton, sugarcane and rice. It is locally frequent in orchards, especially in Mediterranean climates, in pastures, and in nurseries. Finally, it is a frequent weed of amenity turf and is particularly troublesome on heavily-worn and compacted areas such as football pitches.
Host Plants and Other Plants AffectedTop of page
|Actinidia chinensis (Chinese gooseberry)||Actinidiaceae||Other|
|Allium cepa (onion)||Liliaceae||Main|
|Apium graveolens (celery)||Apiaceae||Main|
|Asparagus officinalis (asparagus)||Liliaceae||Other|
|Avena sativa (oats)||Poaceae||Main|
|Beta vulgaris (beetroot)||Chenopodiaceae||Main|
|Beta vulgaris var. saccharifera (sugarbeet)||Chenopodiaceae||Main|
|Brassica napus var. napobrassica (swede)||Brassicaceae||Main|
|Brassica napus var. napus (rape)||Brassicaceae||Main|
|Brassica oleracea (cabbages, cauliflowers)||Brassicaceae||Main|
|Brassica oleracea var. botrytis (cauliflower)||Brassicaceae||Other|
|Brassica oleracea var. gemmifera (Brussels sprouts)||Brassicaceae||Other|
|Brassica oleracea var. viridis (collards)||Brassicaceae||Other|
|Cicer arietinum (chickpea)||Fabaceae||Other|
|Cichorium intybus (chicory)||Asteraceae||Main|
|Cynara cardunculus var. scolymus (globe artichoke)||Asteraceae||Other|
|Daucus carota (carrot)||Apiaceae||Main|
|Festuca arundinacea (tall fescue)||Poaceae||Other|
|Fragaria vesca (wild strawberry)||Rosaceae||Main|
|Glycine max (soyabean)||Fabaceae||Main|
|Helianthus annuus (sunflower)||Asteraceae||Main|
|Hordeum vulgare (barley)||Poaceae||Main|
|Humulus lupulus (hop)||Cannabaceae||Other|
|Ipomoea batatas (sweet potato)||Convolvulaceae||Main|
|Juglans regia (walnut)||Juglandaceae||Other|
|Lens culinaris subsp. culinaris (lentil)||Fabaceae||Other|
|Linum usitatissimum (flax)||Main|
|Lolium perenne (perennial ryegrass)||Poaceae||Other|
|Lotus corniculatus (bird's-foot trefoil)||Fabaceae||Other|
|Malus domestica (apple)||Rosaceae||Main|
|Medicago sativa (lucerne)||Fabaceae||Main|
|Narcissus pseudonarcissus (wild lent lily)||Liliaceae||Other|
|Nicotiana tabacum (tobacco)||Solanaceae||Main|
|Oryza sativa (rice)||Poaceae||Main|
|Papaver somniferum (Opium poppy)||Papaveraceae||Other|
|Pimpinella anisum (aniseed)||Apiaceae||Other|
|Pisum sativum (pea)||Fabaceae||Main|
|Prunus armeniaca (apricot)||Rosaceae||Main|
|Prunus persica (peach)||Rosaceae||Main|
|Quercus robur (common oak)||Fagaceae||Other|
|Ricinus communis (castor bean)||Euphorbiaceae||Other|
|Saccharum officinarum (sugarcane)||Poaceae||Main|
|Secale cereale (rye)||Poaceae||Main|
|Solanum lycopersicum (tomato)||Solanaceae||Other|
|Solanum tuberosum (potato)||Solanaceae||Main|
|Sorghum bicolor (sorghum)||Poaceae||Other|
|Trifolium repens (white clover)||Fabaceae||Other|
|Triticum aestivum (wheat)||Poaceae||Main|
|Vicia faba (faba bean)||Fabaceae||Other|
|Vicia sativa (common vetch)||Fabaceae||Other|
|Vitis vinifera (grapevine)||Vitaceae||Main|
|Zea mays (maize)||Poaceae||Main|
Biology and EcologyTop of page P. aviculare regenerates exclusively by seed (Grime et al., 1988) and is often one of the most abundant species in seed banks of cultivated soils in temperate Europe (Macchia et al., 1996). Densities as high as 200 to 5000 seeds/m² are common (Holm et al., 1997), with most seeds being buried in the upper 5 cm of soil. Optimum germination depth is 0-2 cm. Seed viability in soil decreases exponentially with time, with less than 10% remaining viable after 2 years (Holm et al., 1997). Deep, undisturbed seeds are the most likely to remain dormant. Viable seeds have been recovered after up to 60 years of burial (Campagna and Rapparini, 1997; Holm et al., 1997).
P. aviculare has a cyclic dormancy pattern in soil; fresh seeds show innate dormancy and low temperatures stimulate release from dormancy of imbibed seeds (chilling requirement is typically <5-10 °C for 10 weeks) while high temperatures induce secondary dormancy. Therefore, P. aviculare usually germinates in a single flush during a short period early in the spring (between late February and early May in England, between August and November in Argentina). Seeds that fail to germinate in the spring enter secondary dormancy and no subsequent germination usually occurs in the summer (Courtney, 1968). In Argentina, the temperature range in which germination could occur was estimated to fall between 8°C and 25°C and the estimated required thermal time for germination of 50% of the non-dormant fraction was 80 degree-days above a base temperature of 0°C (Kruk and Benech-Arnold, 1998).
The first seeds are usually shed two months after emergence, and can be produced over an extended period of time (up to 6 months or more unless the plant is killed by frost, for instance from June to November in England (Grime et al. 1988)). A single plant can produce up to 6000 seeds, but this number is highly variable, depending on competition and resource availability (Meerts, 1995; Holm et al., 1997).
The removal of shoot apices resulted in reduced apical dominance and increased branching intensity and this was accompanied by reduced fitness estimates (McPhee et al., 1997).
P. aviculare, even defined in the narrow sense as specified in the Notes on Taxonomy and Nomenclature, is a highly polymorphic species. There exists considerable genetic variation in growth habit and life history traits, including growth rate, flowering date, number of seeds and life span (Meerts, 1992, 1995; Meerts and Garnier, 1996). Chilling requirement also varies among populations (Holm et al., 1997). In addition, the species shows extensive phenotypic plasticity in response to soil fertility, soil moisture, and disturbance regime (trampling) (Meerts, 1995). Genotypes with contrasting life-histories might be adapted to different cultivation practices and disturbance regimes. For instance, short-lived, early flowering genotypes could be favoured in crops subjected to weeding activities in early summer; by contrast, longer-lived genotypes can resume growth and reproduction after harvest of the crop and are therefore well adapted to cereals.
The flowers seem to be mostly (if not always) self-pollinated (Grime et al., 1988; Meerts et al., 1998), although they can be visited by insects (Bugg et al., 1987).
The high colonizing success of P. aviculare in various kinds of man-disturbed habitats has been ascribed to a suite of complementary attributes (Grime et al., 1988; Meerts, 1995): long lasting seed bank; extensive phenotypic plasticity; selfing mating system; and high genetic diversity compared to other, self-pollinating weeds. It has been shown that populations from arable fields, either tetra- or hexaploid, consist of fixed heterozygotes at several enzymatic loci (Meerts et al., 1998).
P. aviculare contains water-soluble allelochemicals, including long-chain fatty acids and phenolic glycosides, that inhibit germination and seedling growth of crops (lettuce, alfalfa, medic, rice) and several species of weeds, most notably Cynodon dactylon and Chenopodium album (Alsaadawi and Rice, 1982a, 1982b; Kloot and Boyce, 1982; Alsaadawi et al., 1983; Lovett et al., 1986; Chung et al., 1994)
The species has effective mechanisms of seed dispersal by human or other agencies. Seeds occur both as an impurity in the harvested crop and as a contaminant of sown seed. They may be dispersed in mud on footwear or tyre treads and can survive ingestion by stock or by birds (Grime et al., 1988). They can also be transported by irrigation water (Holm et al., 1997).
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Notes on Natural EnemiesTop of page Local decreases in abundance of P. aviculare due to attacks by natural enemies have been reported in Belgium (Bulcke et al., 1994), Italy (Marocchi, 1994) and China (Hu et al., 1989). In the latter two cases, it was concluded that the chrysomelids Gastrophysa polygoni and Entomoscelis orientalis, respectively, deserved further investigation as promising agents for potential biological control programmes.
ImpactTop of page In spite of its short stature, P. aviculare has a significant competitive effect on several crops, including maize (Bulcke et al., 1987); in wheat, it was more competitive than Atriplex patula and Polygonum persicaria and nearly as competitive as Chenopodium album (Harper, 1977); with Linum usitatissimum, it was more competitive than C. album and Stellaria media (Carver et al., 1997). It competes primarily for soil resources with barley (Holm et al., 1997), sugarbeet (Moisey, 1974), maize and beans (Casquero et al., 1993).
Due to its long, trailing shoots it can considerably impair mechanical harvesting of carrots and onions (Knott, 1990).
It has been suggested that its depressive effect on certain crops (lucerne, lettuce, medic, rice, sorghum, cotton) could be partly due to allelopathic effects, possibly mediated by soluble phenolic glycosides (Alsaadawi and Rice, 1982b; Alsaadawi et al., 1983; Lovett et al., 1986; Chung et al., 1994).
P. aviculare is often reported as being difficult to control by standard procedures, especially in sugarbeet. However, true herbicide resistance has been rarely demonstrated (triazine: van Oorschot and Straathof, 1988; amitrole: Bulcke et al., 1988).
The restricted germination period of P. aviculare probably prevents it from becoming one of the world's worst weeds. There are conflicting reports, depending on crop and region, as to recent changes in its abundance due to the long lasting use of herbicides. For instance, increases have been noticed in spring and winter cereals in Sweden (Gummesson, 1979; Hallgren, 1996), in vegetables in Finland (Kaukovirta, 1988), in beet in Austria (Neururer, 1975) and in strawberries in the UK (Clay et al., 1990); declines were reported in winter cereals in Germany (Meisel, 1979), in maize and winter cereals in Hungary (Hunyadi, 1973) and in maize in Spain (Lopez-Garcia and Zaragoza, 1995). In the UK and other European countries, the change towards predominantly winter-sown grain crops has probably been partly responsible for an overall decrease in P. aviculare (Cousens and Mortimer, 1995).
P. aviculare is a frequent weed of amenity turf and is particularly troublesome on heavily-worn and compacted areas such as football pitches (Shildrick, 1990).
In Linum usitatissimum, 5 plants/m² was determined as the economic injury threshold (Carver et al., 1997). The critical period of P. aviculare competition in onion is 5-6 weeks after emergence (Holm et al., 1997). Each 50 g/m² increase in P. aviculare dry matter reduced forage yield in a fescue-lucerne mixed sward by up to 20%, up to weed levels of 150 g/m² (Holm et al., 1997).
P. aviculare is a host for several pests of crops:
Nysius huttoni (Hemiptera, Lygaeidae), in New Zealand (Farrell and Stufkens, 1993), N. vinitor, in Australia (McDonald and Smith, 1988), Heterodera schachtii (Nematoda) in Spain (Lopez and Romero, 1988), H. estonica in Sweden (Andersson, 1978), Ditylenchus dipsaci (Nematoda) in Czechoslovakia (Vlk and Holubcova, 1972), Sitona spp. (Coleoptera, Curculionidae) in Hungary (Nadasy, 1983), Brachycaudus amygdalinus (Hemiptera, Aphidae) in Lebanon (Talhouk, 1977), and strawberry latent ringspot nepovirus in the Netherlands (Caron and Van Hoof, 1974).
A non-TMV-like infection was recovered from the pathogenic fungus Uromyces polygoni living on P. aviculare and was able to be transmitted to Chenopodium quinoa (Yarwood and Hecht Poinar, 1973).
UsesTop of page P. aviculare has long been in use as a medicinal plant of minor importance (Fogelfors, 1984), with a high content of tannins and silica. The starch-rich seeds are eaten by birds and poultry. Due to its high content in amino acids and minerals (Casquero et al., 1993), it has been suggested that it could be used for fodder. P. aviculare and P. plebejum are sometimes eaten by people as 'famine food'.
There has been much recent interest into the allelopathic properties of extracts of P. aviculare (Kim et al., 1995). In particular, an inhibiting effect was demonstrated on Bermuda grass (Cynodon dactylon), one of the world's worst weeds (Alsaasawi and Rice, 1982a). Accordingly, it has been suggested that P. aviculare could be sown or used as a mulch between the rows of cotton and sorghum for the control of Bermuda grass, but this does not seem to have ever been experimented in field conditions.
A fungistatic and fungicidal activity was also recently demonstrated against potato pathogens (Sas Piotrowska et al., 1996) and fungi associated with damping off in sugarbeet seedlings (Sas Piotrowska and Piotrowski, 1997).
Extracts of P. aviculare and Paeonia albiflora showed synergistic effects on tobacco mosaic tobamovirus infection (Lin and Qui, 1987).
P. aviculare is a host of the endophyte Phomopsis emicis (Shivas et al., 1994), and a pathogen of the weeds Emex australis and E. spinosa. In the Czech Republic, two microsporidia (Nosema gastroideae and N. equestris) pathogenic to Colorado potato beetle could be produced from the chrysomelids Gastrophysa polygoni and G. viridula, reared on P. aviculare (Hostounsky, 1984).
Some 36 species of insects feed on the flowers of P. aviculare in California, USA (Bugg et al., 1987), 29 of which are entomophagous insects (for example, Geocoris); therefore, it has been suggested that P. aviculare could be used to improve biological control of insect pests on radishes, species of Capsicum and lucerne.
Being tolerant of trampling and soil compaction, P. aviculare has been proposed as a cover plant for heavily trampled areas; in addition, a certain degree of salt tolerance has been demonstrated (Foderaro and Ungar, 1997), making it suitable for turfing of road medians subjected to high inputs of de-icing salt in Canada (Saint-Arnaud and Vincent, 1988) and for phytoextraction of salt from soil contaminated by brine (Foderaro and Ungar, 1997).
Uses ListTop of page
- Erosion control or dune stabilization
Human food and beverage
- Emergency (famine) food
- Poisonous to mammals
Similarities to Other Species/ConditionsTop of page See also Notes on Taxonomy and Nomenclature.
P. arenastrum is a closely related taxon of disputed rank. Flowers and fruits offer the most reliable discriminant characters: P. arenastrum typically has the tepals fused for one third to one half of their length, achenes 1.4-2.5 mm long, with two convex and one much narrower, concave, side (P. aviculare sensu stricto: tepals fused for less than one third of length, achenes 2-3.5 mm long, with three concave sides). In addition, P. arenastrum usually has a more prostrate growth habit and smaller leaves, but these and other vegetative traits show extensive phenotypic plasticity in the whole aggregate. P. arenastrum most often occurs in trampled sites and is apparently much less often found as a weed of cultivated fields than P. aviculare sensu stricto.
P. plebejum is a common weed in a restricted region of central Asia, where it occurs in wheat (Singh, 1997), onion (Iqbal et al., 1990), lentil (Dangol, 1990), paddy rice, maize and potato (Neogi and Rao, 1980). P. plebejum replaces, or co-exists with, P. aviculare as a widespread weed in a restricted region of central Asia, including India (Madhya Pradesh: Singh, 1997; Bihar: Pandey et al., 1995; Meghalaya: Neogi and Rao, 1980), Pakistan (Iqbal et al. 1980) and Nepal (Dangol, 1990). It is also present in Australia, Egypt, Taiwan and Vietnam (Holm et al., 1979), but its status as a weed in those countries is less clear. P. plebejum is smaller, with a short compact stem, 6-15 (-30) cm long, and short internodes. Leaves narrower, 6-25 mm long, 1-2 mm wide, with parallel sides. Perianth-segments ca 1.5 mm long, bright pink. Nut ca 1-1.5 mm long, black and shiny (Lousley and Kent, 1981).
P. patulum is a related species occasionally found as a weed from southern Europe and the Mediterranean area eastwards to Central Asia. It can be distinguished by its inflorescences, consisting of very lax, elongate slender terminal spikes with the flowers in the axils of much reduced, lanceolate-subulate bracts.
Other, taxonomically unrelated, species share a superficial resemblance to P. aviculare due to a prostrate growth habit, and small, greenish flowers in the axils of entire leaves, for instance: Euphorbia maculata, E. prostrata, E. nutans and Herniaria spp.
Prevention and ControlTop of page
Careful control is necessary to prevent the build up of large seed reserves in persistent seed banks.
The following methods have been successfully applied, but they are rarely sufficient on their own; they should preferably be combined with chemical control.
- hoeing with or without chain harrowing, in winter wheat in Iran (Rafii, 1993);
- two harrowings in winter reduced the need for pre-emergence treatment in beet in Italy (Re et al., 1996);
- solarization was successful in Spain (Dalmau et al., 1993) and China (Zhang et al., 1992);
- in an organic farming system the negative consequences of late weed development in wheat were diminished by undersowing with Medicago lupulina and Trifolium repens (Hartl, 1989);
- drilling (Fernandez Quintanilla et al., 1984) and shallow soil disturbance (tining) (Pollard and Cussans, 1981);
- use of long straw wheat varieties, sown at high densities with high nitrogen (Grundy et al., 1997).
- 99% decline of seed bank in 5 years was observed in autumn sown crops (wheat and rape) that were ploughed annually, during which period no return of weed seed was permitted (Lawson et al., 1993).
By contrast, P. aviculare was resistant to flooding in Japan (Tsuruuchi, 1986) and was favoured by bark mulching in apple orchards in Poland (Scibisz et al., 1995). P. aviculare was unpalatable to domestic white China geese (Wurtz, 1995), and grazing was therefore ineffective.
P. aviculare is often reported as being difficult to control, even though true resistance to herbicides has only rarely been demonstrated; to triazine (van Oorschot and Straathof, 1988) and amitrole (Bulcke et al., 1988). As a rule, it is much more resistant when mature than at the seedling stage.
Pre-emergence treatments are recommended, with simazine, terbuthylazine, metribuzin, ethofumesate, cyanazine, metamitron, lenacil, or combinations of these, such as metamitron + ethofumesate + lenacil (May and Hilton, 1991; Strijckers, 1992). Seedlings and very young plants (less than six leaves) can be controlled with ioxynil, bromoxynil + bromofenoxim or fluoroxypyr (Strijckers, 1992).
In beets, successful chemical treatments include: phenmedipham or phenmedipham + desmediphame (Strijckers, 1992); triflusulfuron with phenmedipham (Toth and Peter, 1997); pre-emergence treatment with glyphosate, followed by metamitron + lenacil at reduced dose (Campagna and Rapparini, 1997), with two harrowings in winter reducing the need for pre-emergence treatment in Italy (Re et al., 1996). There is some indication of antagonism between chloridazon and triflusulfuron which can result in poor control of P. aviculare (Fisher et al., 1995).
In spring barley, thiameturon-methyl + metsulfuron can be used early or late post-emergence (Espir, 1987). The activity of sulfonylurea herbicides (metsulfuron-methyl and, or tribenuron-methyl and, or triasulfuron) was greatly improved by two adjuvants (an alkoxylated fatty acid polymer and an organosilicone non-ionic surfactant) (Davies et al., 1997). Thifensulfuron-methyl with metsulfuron-methyl is used as a post-emergence herbicide for control of broad-leaved weeds in wheat, barley, oats and triticale in Australia (Arends and Pegg, 1990).
Clomazone is a post-emergence treatment in poppies (Papaver somniferum) in Tasmania (Macleod, 1997).
More than 90% control was achieved with isoxaben, pronamide [propyzamide] and terbutryn in a common vetch-oat intercrop (Caballero et al., 1995).
In peas, pendimethalin + prometryn are used as pre-emergence herbicides in the UK (Brown et al., 1991); bentazone + pendimethlin are also successful (Birkler, 1988). In chickpea, pre-emergence application of cyanazine, metribuzin and terbuthylazine, or their mixtures, provided an effective level of control of broadleaf weeds (Dastgheib et al., 1995).
In Jordan, the critical period of weed interference in bean (Phaseolus vulgaris) was between 14 and 21 days after emergence (Qasem, 1995).
Aclonifen (+ linuron) are successfully used in maize, sunflowers, tobacco, tomatoes, potatoes and peas in Italy (Anon., 1993).
Aziprotryne + clethodim are in use in cabbage (Dastgheib and Popay, 1995).
In Pimpinella anisum, trifluralin, linuron and prometryn, applied before sowing, pre-emergence and post-emergence, respectively, gave good control (Tepe et al., 1994).
In flax and linseed, bentazone with bromoxynil applied post-emergence are effective (Brochard and Gosselin, 1995).
In apple orchards, pendimethalin or terbacil can be added to simazine (Clay et al., 1990).
In amenity turf, if P. aviculare seedlings are evident before reseeding during April-May in the UK, 2,4-D can be applied 2-3 weeks before seeding (Shildrick, 1990); pendimethalin is also efficient (Johnson and Murphy, 1989). Imazethapyr is used for control in grass stands in the USA (Ferrell et al., 1992).
Mamarot and Rodriguez (1997) provide suggestions for use of herbicides and herbicide mixtures in a wide range of crops in France. These include atrazine in maize and sorghum, bromoxynil plus bentazon inn linseed, thifensulfuron plus tribenuron, or metsulfuron in wheat and barley, oxadiazon in soyabean and sunflower, propyzamide in peas.
Two natural enemies have been suggested as being of potential interest for biological control: the chrysomelids Entomoscelis orientalis and Gastrophysa polygoni, both of which have been circumstantially reported to cause local decrease in abundance of P. aviculare during particular years (Hu et al., 1989; Marocchi, 1994). However, extensive field tests have apparently never been performed.
ReferencesTop of page
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Distribution MapsTop of page
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