Datasheet

Enhanced

10 March 2008

Pennisetum polystachion (mission grass)

Author: C ParkerAuthors Info & Affiliations

Publication: CABI Compendium

39770

https://doi.org/10.1079/cabicompendium.39770

Datasheet Types: Pest, Natural enemy, Invasive species

Abstract

This datasheet on Pennisetum polystachion covers Identity, Overview, Distribution, Dispersal, Hosts/Species Affected, Diagnosis, Biology & Ecology, Environmental Requirements, Natural Enemies, Impacts, Uses, Prevention/Control, Further Information.

Identity

Preferred Scientific Name: Pennisetum polystachion (L.) Schult. (1824)
Preferred Common Name: mission grass
Other Scientific Names: Cenchrus setosus Swartz 1788; Gymnothrix geniculata Schult. 1824; Panicum barbatum Roxb. 1820; Panicum cauda-ratti Schum. 1827; Panicum cenchroides L. Rich. 1792; Panicum densispica Poir. in Lam. 1816; Panicum erubescens Willd. 1809; Panicum longisetum Poir. in Lam. 1816; Panicum polystachion Linnaeus, 1759; Panicum subangustum Schum. 1827; Panicum triticoides Poir. in Lam. 1816; Pennisetum atrichum Stapf & Hubbard 1933; Pennisetum borbonicum Kunth 1830; Pennisetum cauda-ratti (Schum.) Franch. 1895; Pennisetum elegans Nees ex Steud. 1854; Pennisetum flavescens Presl. 1830; Pennisetum gracile Benth. in Hook. 1849; Pennisetum hirsutum Nees 1820; Pennisetum nicaraguense Fourn. 1880; Pennisetum pallidum Nees 1820; Pennisetum polystachion ssp. atrichum (Stapf & Hubbard) Brunken 1979; Pennisetum polystachion ssp. setosum (Swartz) Brunken 1979; Pennisetum purpuracens H.B.K. 1816; Pennisetum reversum Hack. ex Buettn. 1890; Pennisetum reversum var. gymnochaetium Hack. 1901; Pennisetum richardii Kunth 1829; Pennisetum setosum (Swartz) L. Rich. 1805; Pennisetum sieberi Kunth 1829; Pennisetum stenostachyum A. Peter in Feddes 1931; Pennisetum subangustum (Schum.) Stapf & Hubbard 1933; Pennisetum tenuispiculata Steud (1854); Pennisetum uniflorum H.B.K. 1816
International Common Names: English
feather pennisetum
thin napiergrass
west indian pennisetum; French
queue de chat
Local Common Names: Brazil
capim-avião
capim-custodio
capim-mandante
capim-oferecido; Fiji
o tamata; Micronesia, Federated states of
dipw rais
mechen katu
pwokso; Palau
desum
EPPO code: PESPO (Pennisetum polystachion)
EPPO code: PESSE (Pennisetum setosum)

Pictures

Panicle
Spikelets yellow-brown, solitary, sessile, lanceolate, 2.5-5.0 mm long, 0.6-0.9 mm wide, surrounded by numerous bristles.
©Colin Wilson

Inflorescence
Infloresence yellow to brown or purple, one to several erect or drooping spike-like panicles, bristles densely hairy at the base, unequal in size, 1-2.5 cm long.
Bill Parsons

Growth habit
Erect, annual or perennial grass. Flowering culms slender to fairly stout, erect or ascending, 0.3-3 m or more tall, in dense stands, several emerging from a crown.
©Colin Wilson

Growth habit
Mission grass growing by the roadside in Fiji.
Bill Parsons

Infestation in pine plantation
Pennisetum polystachion infesting young pine plantation. Fiji.
©Chris Parker/Bristol, UK

Roadside infestation
Mission grass has become an important roadside weed - seen here in Fiji.
Bill Parsons

Summary of Invasiveness

P. polystachion is a vigorous annual or perennial grass growing to over 1 m height, producing large numbers of seeds with limited dormancy. It is a natural invader of disturbed ground, typically occurring in fallow land in its native region in Africa. It has been widely introduced to Asia, Australia and Central and South America, both deliberately, as a potential forage plant, and accidentally. In some of these areas, especially Thailand and northern Australia, it has flourished, spreading along roadsides into both agricultural and natural habitats, sometimes in national parks and nature reserves, reducing species diversity and greatly increasing the risk of damaging fires. It is listed as a Federal Noxious Weed in USA and as a Class B and C Noxious Weed in the Northern Territory, Australia.

Taxonomic Tree

Notes on Taxonomy and Nomenclature

Perennial forms of this variable weed are sometimes distinguished as a separate species, Pennisetumsetosum (Sw.) L. Rich., while those with smaller spikelets and bristles may be distinguished as P.subangustum (Schum.) Stapf & Hubbard. Most authorities, however, treat ‘P.setosum’ as a sub-species, ssp.setosum, along with the commonest annual form, ssp. polystachion and ssp.atrichum, which differs in having glabrous bristles. ‘P.subangustum’ with shorter spikelets (up to 3 mm) and bristles (longest only up to 12 mm) is treated as a distinct species in West Africa (Hepper, 1972; Schmelzer and Renno, 1999), while in East Africa, Clayton and Renvoize (1982) treat it only as a variant of P. polystachion, noting that there is a continuum of spikelet and bristle lengths across the two forms. All these forms are included under P. polystachion in this datasheet.

Note that ‘P.polystachyon’ is a common mis-spelling.

Plant Type

Annual

Biennial

Grass / sedge

Herbaceous

Perennial

Seed propagated

Description

P. polystachion is an erect, annual or perennial grass with extensive and fibrous roots to a depth of 1 m. Flowering culms slender to fairly stout, erect or ascending, 0.3-3 m or more tall, 5- to 10-noded, with axillary branching, tufted, in dense stands, several emerging from a crown; sometimes rooting at the nodes. Internodes grooved and glabrous. Leaf sheaths thin, keeled toward the blade, usually shorter than the internodes, distinctly nerved and glabrous; ligule a hairy ring, 1.5-2.5 mm long; blades narrow, acuminate, flat, 5-45 cm long, 3-18 mm wide, smooth or hairy with scattered setaceous hairs; prophyllum 5.5-14 cm long.

Inflorescence yellow to brown or purple, one to several erect or drooping spike-like panicles, linear; primary branches a single sessile spikelet subtended by an involucre of unfused plume-like bristles, disarticulating at the base of the branch; main axis 5-35 cm long, 0.5-2.6 mm in diameter, scabrous on the angles, sharp decurrent wings below the point of disarticulation; bristles densely hairy at the base, unequal in size, 1-2.5 cm long, antrorsely barbed, not fused, forming an annular ring about the base of the involucre; callus differentiated, hairy, but not prolonged into a distinct stipe.

Spikelets yellow-brown, solitary, sessile, lanceolate, 2.5-5.0 mm long, 0.6-0.9 mm wide, surrounded by numerous bristles, 2-flowered, the lower floret infertile, the upper floret fertile, smooth and shiny, falling from the spike with bristles attached. Glumes and lower lemma much thinner and more delicate than the upper lemma; apex of lower lemma tridentate. First glume usually absent or minute, rarely, if ever, half as long as the lower lemma, sometimes represented by a vestigial scale, up to 2.5 mm long, nerveless; second glume glabrous but frequently with some scattered spicules on the surface, distinctly 5-nerved, pointed, longer than the lemma, sometimes 3- to 10-lobed; lower lemma 2.3-4.1 mm long, 3- to 5-nerved; palea of lower floret absent or normally developed; upper floret perfect; upper lemma 2.1-3.1 mm long, acute to rounded, distinctly harder in texture than the lower lemma and second glume; anthers 0.8-1.2 mm long. Seed (grain) yellow-brown, 3-5 mm long, surrounded by bristles.

Adapted from Andrews, 1956; Holm et al., 1977; Reed, 1977; Hafliger and Scholz, 1981; Westbrooks, 1989; Parsons and Cuthbertson, 1992.

Distribution

There is some uncertainty over the original native range of P. polystachion. Many sources assume natural distribution in Asia as well as Africa. USDA-ARS (2008), however, indicates that P. polystachion sensu stricto is native to Africa only. In India Bor (1960) indicates it is ‘only an introduction’. The status of the perennial form ‘P. setosum’ is equally uncertain as USDA-ARS (2008) fails to identify a native range, which may perhaps include South America.

Distribution Map

Distribution Table

History of Introduction and Spread

P. polystachion is certainly native in tropical Africa, but is also now very widely present in Asia, Australia and the Pacific and, in its perennial ‘P.setosum’ form, in Central and South America as well as in Africa and locally in India (Bor, 1960), Thailand and Malaysia. The species rarely extends beyond latitudes 23°N and 23°S (Holm et al., 1977). In a survey conducted from 1984 to 1987, it was found that P. polystachion is abundant in northern, north-eastern, and central regions of Thailand, and was moderately abundant elsewhere in the country (Harada et al., 1991). In Thailand, it was considered, in the 1960s, to be a relatively recent introduction, presumed to have come from Myanmar, and know then locally as ‘Burma grass’ or ‘communist grass’. It is thought to have arrived in Malaysia from Thailand in the early 1980s, and by 1988, it was widespread and had infested at least 10 square kilometres of roadsides (Bakar et al., 1990). In Nigeria, it is more abundant in the derived savannah zone than in the slightly drier Guinea Savannah zones (Ekeleme and Chikoye, 2003).

Introductions

Introduced to	Introduced from	Year	Reasons	Introduced by	Established in wild through		References	Notes
Introduced to	Introduced from	Year	Reasons	Introduced by	Natural reproduction	Continuous restocking	References	Notes
USA	West Africa	1990s	Seed trade (pathway cause)		No	No	Westbrooks (1989)	Intercepted at border

Risk of Introduction

The risk of introduction appears to be moderately high. In the USA, P. polystachion has been repeatedly intercepted by border clearance personnel from the USDA as a contaminant of imported commodities. It has been intercepted in miscellaneous cargo from Mali, imported seeds from Chad and straw packing from West Africa (Westbrooks, 1989). Smither-Kopperl (2007) notes that in the years 2005 and 2006, P. polystachion was among the 3 most commonly intercepted noxious weeds at the air, sea and land borders of Washington State, USA. P. polystachion is listed as a Federal Noxious Weed in the USA (Westbrooks, 1989), and is listed as a Class B and C Noxious Weed in the Northern Territory, Australia (Parsons and Cuthbertson, 1992).

Means of Movement and Dispersal

Natural Dispersal (Non-Biotic)

The light, fluffy seeds, because of their bristles, are well equipped for dispersal by wind. They are also spread by water along streams (Westbrooks, 1989; Parsons and Cuthbertson, 1992).

Vector Transmission (Biotic)

The seeds readily attach to animal wool and fur for local distribution.

Accidental Introduction

Local and long-distance spread can occur as a result of attachment of the seeds to clothing, bags and wool, and as a contaminant in hay, grain, and crop seeds, also attached to road vehicles.

In 1989-90, seeds of 88 species of plants, including P. polystachion, were collected from tourist vehicles at a campsite in Kakadu National Park, in Northern Territory, Australia. The seeds were collected by vacuuming the radiator and outer surfaces of each car and by sampling mud from wheel wells and tyres. Individual cars were found to carry up to 789 seeds and a maximum of 15 species. However, 96% of the 304 cars sampled carried one or no seeds. It was concluded that, in view of the low density of weed seeds entering the park on tourist vehicles, resources would be best spent on detecting and eradicating existing weed infestations, rather than on attempts to prevent this form of seed movement (Lonsdale and Lane, 1994).

Intentional Introduction

P. polysctachion has been deliberately introduced quite widely as a forage grass species, for trials and for commercial growing. The history of such introductions, however, is not well documented.

Pathway Causes

Pathway cause	Notes	Long distance	Local	References
Animal production (pathway cause)		Yes	Yes	Choubey and Bhagat (2005)
Botanical gardens and zoos (pathway cause)			Yes
Crop production (pathway cause)	As a catch crop for stemborers	Yes	Yes	Matama-Kauma et al. (2006) Ndemah et al. (2002)
Forage (pathway cause)		Yes	Yes	Choubey and Bhagat (2005)
Seed trade (pathway cause)		Yes		Westbrooks (1989)

Pathway Vectors

Pathway vector	Notes	Long distance	Local	References
Clothing, footwear and possessions (pathway vector)		Yes
Containers and packaging - non-wood (pathway vector)		Yes	Yes
Hides, trophies and feathers (pathway vector)		Yes	Yes
Land vehicles (pathway vector)	Very low seed numbers		Yes	Lonsdale and Lane (1994)
Luggage (pathway vector)		Yes
Water (pathway vector)			Yes	Parsons and Cuthbertson (1992)
Wind (pathway vector)			Yes	Parsons and Cuthbertson (1992)

Hosts/Species Affected

In addition to the crops listed, many other annual and perennial crops are affected, together with pasture, turf and forestry species.

Host Plants and Other Plants Affected

Host	Family	Host status
Bambusa vulgaris (common bamboo)	Poaceae	Main
Camellia sinensis (tea)	Theaceae	Main
Elaeis guineensis (African oil palm)	Arecaceae	Other
Ficus elastica (rubber plant)	Moraceae	Other
Glycine max (soyabean)	Fabaceae	Main
Gossypium (cotton)	Malvaceae	Main
pastures		Main
Sorghum bicolor (sorghum)	Poaceae	Main
Zea mays (maize)	Poaceae	Main

Similarities to Other Species/Conditions

P. polystachion and P.pedicellatum both belong to a section of the genus Pennisetum which is characterized by a tridentate lower lemma, decurrent sharp-angled wings on the main axis, and an upper floret that is harder in texture than the lower floral bracts. In addition, the inflorescence of both species is a spike-like panicle and the spikelets are subtended by plume-like bristles. However, P. polystachion can be distinguished from P. pedicellatum by having a single, sessile spikelet in the involucre, and the lower glume minute or small. In P.pedicellatum, there are up to 5 spikelets, at least one of them on a short pedicel. Also the bristles are densely woolly, giving the inflorescence a thicker, softer texture, and the lower glume is 1-3 mm long. Some other species may also cause confusion, especially in Africa.

Habitat

P. polystachion occurs in farmlands, grasslands, upland tropical hills and croplands including perennial crops, especially after forests have been cleared. It is also found in waste places. It is a troublesome weed of plantation crops in Africa, India, upland South-East Asia, Indonesia and the Philippines. It has been grown as an ornamental in Sri Lanka and the Pacific Islands, and as a pasture species in India. It is cultivated in northern Australia. It has been grown experimentally in the Royal Botanic Gardens in Sydney, New South Wales, Australia, and in northern New South Wales, but rarely becomes established outside the tropics (Holm et al., 1977; Hafliger and Scholz, 1981; Westbrooks, 1989; Parsons and Cuthbertson, 1992). It can become dominant in fire climax or subclimax savannahs when soil fertility has declined (Holm et al., 1977). In Fiji, it has invaded hilly, former forest lands that will not support livestock (Parham, 1955), up to 1000 m altitude, also in stream beds and roadsides (PIER, 2008). In Hawaii it colonises dry to mesic exposed areas in agricultural areas and disturbed forest, mostly lowland but to over 2000 m altitude (PIER, 2008).

Habitat List

Category	Sub category	Habitat	Presence	Status
Terrestrial
Terrestrial	Terrestrial – Managed	Cultivated / agricultural land	Principal habitat	Harmful (pest or invasive)
Terrestrial	Terrestrial – Managed	Managed forests, plantations and orchards	Secondary/tolerated habitat	Harmful (pest or invasive)
Terrestrial	Terrestrial – Managed	Managed grasslands (grazing systems)	Secondary/tolerated habitat	Harmful (pest or invasive)
Terrestrial	Terrestrial – Managed	Managed grasslands (grazing systems)	Secondary/tolerated habitat	Productive/non-natural
Terrestrial	Terrestrial – Managed	Disturbed areas	Principal habitat	Natural
Terrestrial	Terrestrial – Managed	Rail / roadsides	Principal habitat	Natural
Terrestrial	Terrestrial – Managed	Urban / peri-urban areas	Secondary/tolerated habitat	Natural
Terrestrial	Terrestrial ‑ Natural / Semi-natural	Scrub / shrublands	Secondary/tolerated habitat	Natural
Littoral		Coastal areas	Secondary/tolerated habitat	Natural

Biology and Ecology

Genetics

Renno et al. (1995) and Schmelzer and Renno (1999) report a range of ploidies in P. polystachion. The sexually reproducing diploid form, known from Burkina Faso, has 2n=18. Apomictic tetrapoid forms are also common in Africa (2n=36), with pentaploid (2n=45) and hexaploid, (2n=54) forms less common. A wider range of ploidy levels is recorded from hilly regions of West Africa. ‘P.subangustum’ is also recorded as diploid, tetraploid and pentaploid, while the perennial ‘P.setosum’ form is known only as a hexaploid in Africa and also in Brazil (Techio et al., 2002), but pentaploid in Bolivia (Norrmann et al., 1994). Genetic variability is greatest in the diploid forms but some does also occur in the polyploids.

Reproductive Biology

Both annual and perennial forms reproduce almost exclusively by seed. The perennial form, ‘P.setosum’, is distinguished mainly by being a tufted or shortly rhizomatous perennial but also by being less branched (Bor, 1960). In the Philippines, it was found that a single plant can produce up to 65 tillers each with eight panicles, resulting in 330,000 seeds. The first tiller emerged 39 days after transplanting or after formation of the fourth or fifth leaf and after application of fertilizer. Percentage germination of dehulled seeds in the dark was consistently lower than in the light up to 77 days after harvesting. Germination of freshly harvested seed is inhibited by darkness, blue and far-red light, and exposure to very high temperatures. When kept in darkness, the seeds did not start germinating until 7 days after harvest whereas in the presence of light, 31% of the seeds germinated when sown 1 day after harvesting, confirming that the seeds are light sensitive. The importance of light was confirmed in Malaysia by Ismail et al. (1994) who showed an increase from 24% germination in the dark to 59% in the light, and an optimum temperature for germination of 35^°C; also by Kiatsoonthorn and Tjitrosemito (1992) who obtained an increase from 2% in the dark to over 40% in the light. Exposure to very low temperatures completely suppressed germination (Fernandez, 1980).

Laboratory experiments in Thailand revealed that the percentage germination of P. polystachion seeds (collected from Kao Kaelae, Thailand) after 1 month of storage was low (27.2%), but after 2-4 months was >90%. Percentage germination declined after 4 months storage to 28% after 12 months. Seeds collected in December had a higher rate of germination than those collected in November or January. Seeds with a diameter of 0.64-0.76 mm also exhibited higher germination rates than those with a diameter of 0.56-0.64 mm. Fertile seed production in spikes gradually decreased from 62.4% in the early part of January to 3.4% in the middle of April. However, the number of spikelets gradually decreased from approximately 175 per culm in the early part of January to 150 per culm in the middle of February, and then increased again to 225 per culm in the middle of April (Kiatsoonthorn, 1991). One study in Australia suggests that seed longevity is very limited, perhaps due to lack of dormancy, such that after a year less than 1% of viable seeds remained (Setterfield et al., 2004).

Phenology

In northern Australia, the seeds of P. polystachion germinate at any time after the opening rains of the wet season (October-November). Rapid growth follows seedling establishment, and flowering commences in late January or February and continues into the early dry season. Growth ceases in June or early July in the southern hemisphere (Parsons and Cuthbertson, 1992).

The first visible sign of the reproductive stage is elongation of the internodes of the primary tiller. The flag leaf forms 18 days after onset of reproduction, followed 2 days later by emergence of the panicle from the flag leaf. The spikelets ripen 28 days after onset of reproduction (Fernandez, 1980).

Environmental Requirements

P. polystachion is a tropical grass, well adapted to soils of low fertility, and occurs mainly in grasslands on sandy soils where native (Weber, 2003). The plant is moderately tolerant of shade. In Thailand, growth was almost normal under only 40% full light, but was severely reduced at only 10% full light (Kobayashi et al., 2003).

Climate

Climate type	Description	Preferred or tolerated
A - Tropical/Megathermal climate	Average temp. of coolest month > 18°C, > 1500mm precipitation annually	Preferred
Af - Tropical rainforest climate	> 60mm precipitation per month	Tolerated
Am - Tropical monsoon climate	Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))	Tolerated
As - Tropical savanna climate with dry summer	< 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])	Preferred
Aw - Tropical wet and dry savanna climate	< 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])	Preferred
Cf - Warm temperate climate, wet all year	Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year	Tolerated
Cw - Warm temperate climate with dry winter	Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)	Tolerated

Latitude/Altitude Ranges

Latitude North (°N)	Latitude South (°S)	Altitude lower (m)	Altitude upper (m)
30	30

Air Temperature

Parameter	Lower limit (°C)	Upper limit (°C)
Mean annual temperature	20	30
Mean maximum temperature of hottest month		35
Mean minimum temperature of coldest month	15

Rainfall

Parameter	Lower limit	Upper limit	Description
Dry season duration	0	8	number of consecutive months with <40 mm rainfall
Mean annual rainfall	500		mm; lower/upper limits

Rainfall Regime

Summer

Bimodal

Soil Tolerances

Soil texture > light

Soil texture > medium

Soil texture > heavy

Soil reaction > acid

Soil reaction > neutral

Soil drainage > free

Special soil tolerances > shallow

Special soil tolerances > infertile

List of Pests

Natural enemy of

Notes on Natural Enemies

Few natural enemies of P. polystachion have been recorded. Waterhouse (1993) lists those records there are, which include species of gall midges, Cecidomyiidae, from Africa and India. Some of these are known pests of pearl millet (P.glaucum), but others may be host specific. He also lists records of fungal pathogens, some may also be host specific but many of them attack crop plants.

Natural enemies

Natural enemy	Type	Life stages	Specificity	References	Biological control in	Biological control on
Magnaporthe oryzae (rice blast disease)	Pathogen	Leaves	not specific

Impact Summary

Category	Impact
Economic/livelihood	Positive and negative
Environment (generally)	Negative

Impact: Economic

P. polystachion quickly invades cultivated fields and wastelands and has thus become a serious weed in cleared uplands of South-East Asia and the Pacific Islands. As a result, these areas soon become unprofitable because cultivation alone will not provide adequate control. In coastal areas of Queensland and the Northern Territory, Australia, it has become an important roadside weed. In Katherine, Northern Territory, Australia, P. polystachion with a density of 32 plants per square metre reduced the grain yield of sorghum from 5680 to 3503 kg/ha. In older stylo (Stylosanthes sp.) pastures in Australia, P. polystachion encroaches on wetter areas, thought to be due to the seed's response to cycles of wet and dry (Parsons and Cuthbertson, 1992). In Australia, P. polystachion provides fuel for very hot fires at the end of the dry season, and may alter natural fire regimes (PIER, 2008).

Impact: Environmental

In Thailand and northern Australia, it has flourished, spreading along roadsides into both agricultural and natural habitats, sometimes into national parks and nature reserves, reducing species diversity and greatly increasing the risk of damaging fires. P. polystachion is one of 89 species (5.8% of the vascular flora) that are regarded as invasive alien plants in the Kakadu National Park in Australia’s Northern Territory. It is considered to be a particularly serious threat in the uplands of the park (Cowie and Werner, 1993).

Douglas et al. (2004) show that a dense growth of P. polystachion increases the fuel load by 5 times, thus greatly increasing the risk of damaging fires, while also reducing the nitrogen status of the soil. In tropical Australia, P. polystachion is spreading along roadsides and thence poses an increasing threat to upland crops (Groves, 1991). In Lampung, Sumatra, Indonesia, P. polystachion is recognized as a serious weed in bamboo (Dendrocalamus asper) plantations (Widjaja and Tjitrosoedirdjo, 1991).

Risk and Impact Factors

Invasiveness

Invasive in its native range

Proved invasive outside its native range

Has a broad native range

Abundant in its native range

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

Impact outcomes

Damaged ecosystem services

Ecosystem change/ habitat alteration

Modification of fire regime

Modification of nutrient regime

Modification of successional patterns

Monoculture formation

Negatively impacts agriculture

Negatively impacts livelihoods

Reduced native biodiversity

Impact mechanisms

Competition - monopolizing resources

Competition - shading

Rapid growth

Likelihood of entry/control

Highly likely to be transported internationally accidentally

Highly likely to be transported internationally deliberately

Difficult to identify/detect as a commodity contaminant

Uses

P. polystachion has been used as a forage crop in Asia and South America. In India, its nutritive value has been studied in detail, as a monocrop, or in combination with a legume. It compared favourably with a range of other species in productivity and tolerance of partial shade (Bhatt et al., 2002a,b), and a system of P. polystachion intercropped with Stylosanthes guianensis was the best of several tested in Bihar, India (Choubey and Bhagat, 2005). It is favoured by goats (Singh and Shankar, 2000). In Africa, it may not be planted deliberately but stands of the weed in fallows are utilized as forage, as in Benin (Agonyissa and Sinsin, 1998).

P. polystachion has also been tested for its ability to attract cereal stemborers away from maize or sorghum crops, though it is less effective in this respect than P. purpureum or Panicum maximum (Ndemah et al., 2002; Matama-Kauma et al., 2006).

The plant has been used in Nigeria as a traditional means of preventing bleeding, but Odeh et al. (2004) failed to confirm that ethanolic extracts do indeed have this property.

Uses List

Environmental > Boundary, barrier or support

Medicinal, pharmaceutical > Traditional/folklore

Animal feed, fodder, forage > Fodder/animal feed

Animal feed, fodder, forage > Forage

Detection and Inspection

In the field, P. polystachion is a vigorous, robust, tussock-forming grass (in clumps) that grows from 2 to 3 m tall. It is characterized at maturity by a spike-like seedhead.P. polystachion is spread mostly by its highly viable seeds. However, the grains alone cannot be used for positive identification (Holm et al., 1977). Shipments of crop seeds from countries or localities that are infested with P. polystachion should be closely examined upon arrival in non-infested areas. Infested shipments should be thoroughly cleaned to minimize further spread.

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.

Prevention

P. polystachion is spread mostly by its highly viable seeds. However, the grains alone cannot be used for positive identification (Holm et al., 1977). Shipments of crop seeds from countries or localities that are infested with P. polystachion should be closely examined upon arrival in non-infested areas. Infested shipments should be thoroughly cleaned to minimize further spread.

Control

As with other annual weeds, the primary concern in control of P. polystachion is to prevent further seed production and to eliminate the seed bank in the soil. Due to successive germinations and the risk of erosion, repeated cultivation is not a practical control method. Instead, a combination of cultivation, herbicides and, in pastures, careful grazing management provides the best results. The grass is also susceptible to fire (Gupta and Trivedi, 2001).

Cultural control and sanitary measures

In rubber plantations in Thailand, shading by the legumes Canavalia ensiformis, Lablab purpureus and Mucuna pruriens provided enough shading to greatly suppress P. polystachion (Kobayashi et al., 2003).

Physical/mechanical control

Seed production can be prevented by mowing or cutting of plants before flowering (Watson, 1986). Isolated plants can be hand pulled or dug out.

Chemical control

The range of herbicides suggested includes glyphosate, glufosinate, paraquat, fluazifop-butyl, haloxyfop-methyl and imazapyr. All are most effective on young plants, or on regrowth following slashing. Longest control is provided by imazapyr, but use of this compound is limited to very few crops. Working with the perennial form, ssp.setosum, good control of young plants is possible with fluazifop-butyl, fenoxaprop-ethyl, glyphosate, glufosinate and paraquat. Faiz (1999), working in rubber in Malaysia also had good results with glyphosate, imazapyr and glufosinate; also with MSMA, but paraquat was less effective. On established plants, best results were obtained with imazapyr, metsulfuron and haloxyfop.

In soyabeans in Brazil, good results are obtained with various combinations of imazethapyr, imazaquin and sethoxydim with bentazon, fomesafen or clethodim; also with haloxyfop-methyl, propaquizafop, fenoxaprop-P-ethyl and fluazifop-P-butyl. These are often combined with a mineral oil and/or surfactant (Barros et al., 1992a,b). Miller (2006) describes that thick stands of P. polystachion in pastures may be treated with glyphosate using a rope-wick applicator, as soon as the weed overtops young pasture plants. In cotton, maize, or sorghum, pre-emergent or post-emergent directed applications of atrazine, ametryn, diuron, fluometuron or paraquat are effective (Parsons and Cuthbertson, 1992).

Recently, P. polystachion in tea plantations in Sri Lanka has been treated by application of diuron on plants that are less than 45 cm high before emergence of inflorescence or flowering. Surfactants may also be used. Phytotoxic effects are seen within 1 week of spraying and complete kill is observed in 2-3 weeks, but the herbicide will not kill mature plants in flower. Glyphosate can also be used for control but is expensive; dalapon is ineffective (Watson, 1986).

Links to Websites

Name	URL	Comment
GISD/IASPMR: Invasive Alien Species Pathway Management Resource and DAISIE European Invasive Alien Species Gateway	https://doi.org/10.5061/dryad.m93f6	Data source for updated system data added to species habitat list.

References

Agonyissa D, Sinsin B, 1998. Productivity and carrying capacity of natural grassland in Benin. (Productivité et capacité de charge des pâturages naturels au Bénin.) Revue d'Élevage et de Médecine Vétérinaire des Pays Tropicaux, 51(3):239-246.

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