Urochloa platyphylla
(broadleaf signalgrass)

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Identity

Preferred Scientific Name

• Urochloa platyphylla (Munro ex C. Wright) R.D. Webster

Preferred Common Name

• broadleaf signalgrass

Other Scientific Names

• Brachiaria extensa Chase
• Brachiaria platyphylla (Munro ex C. Wright) Nash
• Panicum platyphyllum Munro ex C. Wright
• Paspalum platyphyllum Griseb.
• Urochloa extensa (Chase) C.Nelson, Sutherl. & Fern.Casas

International Common Names

• English: white para grass
• Spanish: Gambutera

Local Common Names

• Trinidad and Tobago: wild para

EPPO code

• BRAPP (Brachiaria platyphylla)

Summary of Invasiveness

U. platyphylla is a weedy grass species commonly found in disturbed, open and sandy sites such as crop fields, ditches and roadsides. It is considered a troublesome weed because of its tolerance to some herbicides principally in maize plantations (Chamblee et al., 1982; Gallaher et al.,1999). U. platyphylla is highly adaptable and it is able to germinate and grow throughout a wide range of soil and environmental conditions (Burke et al., 2003). Additionally, its seeds may remain on the crop residue until pre-emergence herbicides are no longer effective in controlling the germinating seeds, at which time the seeds fall to the soil surface and germinate (Alford et al., 2005). 

Taxonomic Tree

• Domain: Eukaryota
•     Kingdom: Plantae
•         Phylum: Spermatophyta
•             Subphylum: Angiospermae
•                 Class: Monocotyledonae
•                     Order: Cyperales
•                         Family: Poaceae
•                             Genus: Brachiaria
•                                 Species: Urochloa platyphylla

Notes on Taxonomy and Nomenclature

The taxonomy of the genus Urochloa is unclear mostly due to the weaknesses of the characters used to separate Urochloa from Brachiaria (i.e., spikelet orientation and presence or absence of an upper floret). These weaknesses have been discussed by several authors including Webster (1987, 1988) and Morrone and Zuloaga (1992, 1993). Floristic studies conducted in Australia (Webster, 1987), North America (Webster, 1988; Zuloaga and Morrone, 2003), South America, Mexico and Central America (Morrone and Zuloaga, 1992, 1993) have circumscribed species of Brachiaria into Urochloa. On the other hand, Sharp and Simon (2002) maintain the name Brachiaria for all species that occur in Australia and the annual species of Brachiaria are now included in the new genus Moorochloa (Veldkamp, 2004). The taxonomic positions of these three genera still remain unclear. The species Urochloa platyphylla is also named as B. platyphylla which is still an accepted name by some authorities (USDA-ARS, 2014). 

Description

U. platyphylla is an annual grass. Culms 25-100 cm, decumbent, rooting at the lower nodes; nodes glabrous. Sheaths glabrous or sparsely pilose; ligules 0.5-1 mm; blades 2.5-17.5 cm long, 3-13 mm wide, glabrous or sparsely pilose, bases subcordate, not clasping the stems, margins ciliate basally, with papillose-based hairs. Panicles 6-16 cm long, 2-2.5 cm wide, with 2-8 spike-like primary branches in 2 ranks; primary branches 3-8 cm, axils pubescent, axes 1.3-2.5 mm wide, flat, usually glabrous, occasionally pilose dorsally; secondary branches rarely present; pedicels shorter than the spikelets, scabrous and sparsely pilose. Spikelets 3.8-5 mm long, 2-2.5 mm wide, ovoid, bi-convex; solitary, appressed to the branches, in 2 rows. Glumes scarcely separated; lower glumes 1.2-1.8 mm, to 1/3 as long as the spikelets, obtuse, glabrous, 5(-7)-veined, not clasping the base of the spikelets; upper glumes 3.2-4.7 mm, glabrous, 7(-9)-veined; lower florets sterile; lower lemmas 3.2-4.7 mm, glabrous, 5-veined; lower paleas present; upper lemmas 2.8-3.4 mm long, 1.8-2.3 mm wide, apices incurved, broadly acute to rounded, mucronulate; anthers about 1 mm. Caryopses 1.5-2.2 mm (Wipff and Thompson, 2003). 

Plant Type

Distribution

U. platyphylla is native to the southeastern United States, Cuba, and South America from Bolivia to Northern Argentina (Clayton et al., 2014). It can be found naturalized in Japan, Europe, Mexico and Central America, the West Indies, and other parts of South America (Clayton et al., 2014; USDA-ARS, 2014). 

Distribution Table

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

History of Introduction and Spread

U. platyphylla is a widespread summer growing weed of cultivation, gardens, roadsides and disturbed places. It is highly accepted that U. platyphylla has been unintentionally introduced into new areas as a contaminant in crop-seeds. Seeds of U. platyphylla often occur as contaminants of maize-seed exported from the USA (USDA-ARS, 2014; USDA-NRCS, 2014). In Belgium it was introduced with soyabeans and birdseed and it was first reported in 1992 (Verloove and Vandenberghe, 1993).

Risk of Introduction

The risk of introduction of U. platyphylla is high, mainly because it can be easily transported internationally as a seed contaminant. 

Habitat

U. platyphylla is a weed commonly found in ditches, roadsides and open and disturbed sites especially on sandy soils (Wipff and Thompson, 2003; Clayton et al., 2014; USDA-NRCS, 2014). 

Habitat List

Hosts/Species Affected

U. platyphylla grows as a weed in maize, groundnuts, rice, soyabean and citrus plantations where it has been documented to reduce yield (Futch and Hall, 2004; Alford et al., 2005; Sesto et al., 2011). 

Host Plants and Other Plants Affected

Growth Stages

Biology and Ecology

Genetics

The chromosome number reported for U. platyphylla is 2n = 36 (Wipff and Thompson, 2003).

Reproductive Biology

In the USA, U. platyphylla flowers from July to September (USDA-ARS, 2014). 

Climate

Air Temperature

Soil Tolerances

Soil reaction

• neutral

Soil texture

• light
• medium

Natural enemies

Notes on Natural Enemies

The following pathogens have been isolated from symptomatic leaves of U. platyphylla and can be frequently also observed on stems and roots:

• Cochliobolus cynodontis
• Cochliobolus lunatus
• Cochliobolus geniculatus
• Setosphaeria rostrata
• Cochliobolus stenospilus

These pathogens generate necrosis and dieback of leaves, stems, and roots, stunting, and plant death (Pratt, 2006). 

Means of Movement and Dispersal

U. platyphylla spreads by seeds. The seeds are tiny and spilled along roadsides, agricultural land and around feedlots where they may germinate, especially if they fall or are washed into ditches or damp places. Once established, U. platyphylla can be spread by implements such as headers, in irrigation and flood water, in soil, in seeds, and in plant debris. 

Pathway Causes

Pathway Vectors

Impact Summary

Economic Impact

U. platyphylla is an environmental and agricultural weed. This grass is very aggressive and can reduce yield in crops. B. platyphylla is a species of concern because it is more difficult to control than other weeds due to its resistance to the most common herbicides, causing great expense to producers (Chamblee et al., 1982; Gallaher et al.,1999; Alford et al., 2005; Sesto et al., 2011).

Risk and Impact Factors

• Proved invasive outside its native range
• Abundant in its native range
• Highly adaptable to different environments
• Is a habitat generalist
• Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
• Pioneering in disturbed areas
• Benefits from human association (i.e. it is a human commensal)
• Fast growing

• Ecosystem change/ habitat alteration
• Modification of hydrology
• Modification of successional patterns
• Negatively impacts agriculture
• Reduced native biodiversity

• Competition - monopolizing resources
• Herbivory/grazing/browsing
• Rapid growth

• Highly likely to be transported internationally accidentally
• Difficult to identify/detect as a commodity contaminant
• Difficult/costly to control

Uses

U. platyphylla is sometimes used as a forage for livestock (USDA-ARS, 2014). 

Uses List

Animal feed, fodder, forage

• Forage

Prevention and Control

Even when U. platyphylla is resistant to some of the most common herbicides, studies have shown that infestations can be effectively controlled with the herbicides such as Armezon [topramezone], Accent [nicosulfuron], and Glyphosate (Martin, 2001; Alford et al., 2005). For example, applications of Accent at 0.67 oz/A can provide approximately 90% control of U. platyphylla. To achieve maximum control of emerged plants, treatments should be made before plants produce seeds (Martin, 2001). In another study, U. platyphylla in maize fields was killed at various time intervals during the growing season by applying post-emergent glyphosate. In this study, maize injury was avoided by the use of a glyphosate-tolerant variety (Alford et al., 2005).

References

Alanen A; Bongard T; Einarsson E; Hansen H; Hedlund L; Jansson K; Josefsson M; Philipp M; Sandlund OT; Svart ÂE; Svart HE; Weidema I, 2004. Introduced Species in the Nordic Countries (Denmark) under Nordic Council of Ministers (NMR). Natur-og Friluftslivsgruppen.

Alford JL; Hayes RM; Rhodes GN Jr; Steckel LE; Mueller TC, 2005. Broadleaf signalgrass (Brachiaria platyphylla) interference in corn. Weed Science, 53(1):97-100.

Brathwaite CWD; Pollard GV; Elango F; Haque SQ; Persad CG; Bala G; Brathwaite RAI; Griffith SM, 1987. Guidelines for the identification and diagnosis of damage in crop plant caused by insects, diseases, weed and nutrients disorders. Port Spain, Trinidad and Tobago: Inter-American Institute for Cooperation on Agiculture (IICA), 160 pp.

Burke IC; Thomas WE; Spears JF; Wilcut JW, 2003. Influence of environmental factors on broadleaf signalgrass (Brachiaria platyphylla) germination. Weed Science, 51(5):683-689.

Chamblee RW; Thompson L Jr; Coble HD, 1982. Interference of broadleaf signalgrass (Brachiaria platyphylla) in peanuts (Arachis hypogaea). Weed Science, 30(1):45-49.

Clayton WD; Govaerts R; Harman KT; Williamson H; Vorontsova M, 2014. GrassBase - The Online World Grass Flora. http://www.kew.org/data/grasses-db.html

DAISIE, 2014. Delivering Alien Invasive Species Inventories for Europe. European Invasive Alien Species Gateway. www.europe-aliens.org/default.do

Futch SH; Hall DW, 2004. Identification of Grass Weeds in Florida Citrus. Document HS955., USA: Horticultural Sciences Department, Florida Cooperative Extension Service, University of Florida, 7 pp. [Journal Series No. T-00610.] http://edis.ifas.ufl.edu

Gallaher K; Mueller TC; Hayes RM; Schwartz O; Barrett M, 1999. Absorption, translocation, and metabolism of primisulfuron and nicosulfuron in broadleaf signalgrass (Brachiaria platyphylla) and corn. Weed Science, 47(1):8-12.

Martin JR, 2001. Broadleaf signalgrass control in corn. Kentucky Pest News. The Bulletin, IPM 914. http://www.uky.edu/Ag/kpn/pdf/kpn_914.pdf

Morrone O; Zuloaga FO, 1992. A revision of the native and introduced South American species of Brachiaria (Trin.) Griseb. and Urochloa P. Beauv. (Poaceae: Panicoideae: Paniceae). (Revisión de las especies sudamericanas nátivas e introducidas de los géneros Brachiaria y Urochloa (Poaceae: Panicoideae: Paniceae).) Darwiniana, 31(1-4):43-109.

Morrone O; Zuloaga FO, 1993. Synopsis of the genus Urochloa (Poaceae: Panicoideae: Paniceae) from Mexico and Central America. (Sinopsis del género Urochloa (Poaceae: Panicoideae: Paniceae) para Mexico y América Central.) Darwiniana, 32:59-75.

Pratt RG, 2006. Johnsongrass, yellow foxtail, and broadleaf signalgrass as new hosts for six species of Bipolaris, Curvularia, and Exserohilum pathogenic to bermudagrass. Plant Disease, 90(4):528.

Sesto ME; Schabes FI; Sigstad EE, 2011. A calorimetric study of the interaction between Brachiaria platyphylla and soil microbial activity. Thermochimica Acta, 526:157-162.

Sharp D; Simon BK, 2002. AusGrass1: Grasses of Australia. Canberra and Queensland, Australia: Australian Biological Resources Study and Environmental Protection Agency.

Shirasuna RT, 2014. Urochloa in Lista de Espécies da Flora do Brasil ([English title not available]). Rio de Janeiro, Brazil: Jardim Botânico do Rio de Janeiro. http://reflora.jbrj.gov.br/jabot/floradobrasil/FB24316

Stevens PF, 2012. Angiosperm Phylogeny Website. http://www.mobot.org/MOBOT/research/APweb/

USDA-ARS, 2014. Germplasm Resources Information Network (GRIN). Online Database. Beltsville, Maryland, USA: National Germplasm Resources Laboratory. https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch.aspx

USDA-NRCS, 2014. The PLANTS Database. Baton Rouge, USA: National Plant Data Center. http://plants.usda.gov/

Veldkamp JF, 2004. Miscellaneous notes on mainly Southeast Asian gramineae. Reinwardtia, 12:135-140.

Verloove F; Vandenberghe C, 1993. [English title not available]. (Nieuwe en interessante graanadventieven voor de Noordvlaamse en Noordfranse flora, hoofdzakelijk in 1992.) Dumortiera, 54:35-57.

Webster RD, 1987. Australian Paniceae (Poaceae). Berlin, Germany: J. Cramer, 322pp.

Webster RD, 1988. Genera of the North American Paniceae (Poaceae: Panicoideae). Systematic Botany, 13(4):576-609.

Wipff JK; Thompson RA, 2003. Urochloa. In: Flora of North America vol. 25 [ed. by Barkworth, M. E. \Capels, K. M. \Long, S. \Piep, M. B.]. http://herbarium.usu.edu/webmanual

Links to Websites

Contributors

5/06/15 Updated by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

25/11/14 Original text by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA

Distribution Maps