Invasive Species Compendium

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Datasheet

Digitaria insularis
(sourgrass)

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Datasheet

Digitaria insularis (sourgrass)

Summary

  • Last modified
  • 16 November 2018
  • Datasheet Type(s)
  • Invasive Species
  • Pest
  • Host Plant
  • Preferred Scientific Name
  • Digitaria insularis
  • Preferred Common Name
  • sourgrass
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Spermatophyta
  •       Subphylum: Angiospermae
  •         Class: Monocotyledonae
  • Summary of Invasiveness
  • D. insularis is an aggressive perennial grass causing major weed problems in its native area, especially in Brazil, Paraquay and Bolivia. It was classed as a principal weed in Venezuela by

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Pictures

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PictureTitleCaptionCopyright
Digitaria insularis (sourgrass); habit at Mokolii, Oahu. April 19, 2005
TitleHabit
CaptionDigitaria insularis (sourgrass); habit at Mokolii, Oahu. April 19, 2005
Copyright©Forest & Kim Starr Images-2005 - CC-BY-3.0
Digitaria insularis (sourgrass); habit at Mokolii, Oahu. April 19, 2005
HabitDigitaria insularis (sourgrass); habit at Mokolii, Oahu. April 19, 2005©Forest & Kim Starr Images-2005 - CC-BY-3.0
Digitaria insularis (sourgrass); habit at Nuu Mauka, Maui.  November 27, 2004
TitleHabit
CaptionDigitaria insularis (sourgrass); habit at Nuu Mauka, Maui. November 27, 2004
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Digitaria insularis (sourgrass); habit at Nuu Mauka, Maui.  November 27, 2004
HabitDigitaria insularis (sourgrass); habit at Nuu Mauka, Maui. November 27, 2004©Forest Starr & Kim Starr - CC BY 4.0
Digitaria insularis (sourgrass); seedheads. Sand Island, Midway Atoll.  June 09, 2008
TitleSeedheads
CaptionDigitaria insularis (sourgrass); seedheads. Sand Island, Midway Atoll. June 09, 2008
Copyright©Forest Starr & Kim Starr - CC BY 4.0
Digitaria insularis (sourgrass); seedheads. Sand Island, Midway Atoll.  June 09, 2008
SeedheadsDigitaria insularis (sourgrass); seedheads. Sand Island, Midway Atoll. June 09, 2008©Forest Starr & Kim Starr - CC BY 4.0

Identity

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Preferred Scientific Name

  • Digitaria insularis (L.) Mez ex Ekman

Preferred Common Name

  • sourgrass

Other Scientific Names

  • Andropogon insularis L.
  • Digitaria insularis (L.) Fedde
  • Panicum insulare (L.) G.Mey.
  • Panicum leucophaeum Kunth
  • Trichachne insularis (L.) Nees
  • Valota insularis (L.) Chase

International Common Names

  • Spanish: rabo de zorra

Local Common Names

  • Argentina: pasto amargo
  • Brazil: capim acu; capim amargoso; capim flecha; capim pororo; milhete gigante
  • Cuba: barba de indio; torolico
  • Dominican Republic: yerba de zorra
  • Haiti: barbon des antilles; herbe à ble; herbe pental; z'herbe à blé
  • Puerto Rico: Zorra

Summary of Invasiveness

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D. insularis is an aggressive perennial grass causing major weed problems in its native area, especially in Brazil, Paraquay and Bolivia. It was classed as a principal weed in Venezuela by Holm et al. (1979). It is a major weed where introduced to pastures in Hawaii, USA (Kuswata Kartawinata and Mueller-Dombois, 1972); also in Papua New Guinea (Chadhokar, 1978). In Hawaii, a weed risk assessment based on the Australia/New Zealand model rated the species at 20, i.e. high risk (PIER, 2012).

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Spermatophyta
  •             Subphylum: Angiospermae
  •                 Class: Monocotyledonae
  •                     Order: Cyperales
  •                         Family: Poaceae
  •                             Genus: Digitaria
  •                                 Species: Digitaria insularis

Notes on Taxonomy and Nomenclature

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Digitaria insularis has been known by a large number of synonyms, since originally being described as Andropogon insularis by Linnaeus. Some of the more frequently quoted are included in the tabulated list, but the only one used at all frequently in recent years has been Trichachne insularis. It is included in the Trichachne section of the genus.

Description

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D. insularis is a tufted perennial grass up to 150 cm high. It is referred to as rhizomatous (e.g. Machado et al., 2006) but the rhizomes are extremely short and swollen. Leaves up to 40 cm long, 15 mm wide, finely scabrid along edges. Sheaths hairy, ligule 3-4 mm long. Culms more-or-less erect, up to 10 mm in diameter. Nodes brown, bearded. Inflorescence a panicle up to 30 cm long, comprising up to 50 racemes, narrowly divergent, congested, white to brownish. Spikelets in pairs up to 4 mm long. Lower glume up to 1 mm long, upper glume and lemma with silky hairs exceeding the spikelet. Caryopsis 1.5 mm long.

Detailed discussion of growth forms, branching patterns, and inflorescence structure in some Digitaria species including D. insularis is provided by Rua (2003).

Distribution

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D. insularis is native to the Americas, from Argentina in the south to southern USA in the north. It is assumed to be introduced to the more northern state of Illinois, USA. Elsewhere it has been introduced to the Philippines and a number of Pacific Islands including Fiji, Papua New Guinea and Hawaii. The status of one record from South Africa is uncertain (GBIF, 2012).

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.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Asia

JapanLocalisedIntroducedPIER, 2012Bonin Islands
PhilippinesPresentIntroduced Invasive PIER, 2012

Africa

South AfricaAbsent, unreliable recordGBIF, 2012

North America

USAPresentPresent based on regional distribution.
-AlabamaPresentNativeUSDA-NRCS, 2012
-ArizonaPresentNativeUSDA-NRCS, 2012
-FloridaPresentNativeUSDA-NRCS, 2012
-HawaiiWidespreadIntroduced Invasive USDA-NRCS, 2012
-IllinoisLocalisedIntroducedUSDA-NRCS, 2012
-MississippiPresentNativeUSDA-NRCS, 2012
-TexasPresentNativeUSDA-NRCS, 2012

Central America and Caribbean

Antigua and BarbudaPresentNativeUSDA-ARS, 2012
BahamasPresentNativeUSDA-ARS, 2012
BelizePresentNativeUSDA-ARS, 2012
Cayman IslandsPresentNativeSmithsonian Institution, 2012
Costa RicaPresentNativeUSDA-ARS, 2012
CubaPresent Invasive Oviedo Prieto et al., 2012; USDA-ARS, 2012
DominicaNativeSmithsonian Institution, 2012
Dominican RepublicPresentNativeUSDA-ARS, 2012
El SalvadorPresentNativeUSDA-ARS, 2012
GrenadaPresentNativeUSDA-ARS, 2012
GuadeloupePresentNativeUSDA-ARS, 2012
GuatemalaPresentNativeUSDA-ARS, 2012
HaitiPresentNativeUSDA-ARS, 2012
HondurasPresentNativeUSDA-ARS, 2012
JamaicaPresentNativeUSDA-ARS, 2012
MartiniquePresentNativeUSDA-ARS, 2012
MontserratPresentNativeUSDA-ARS, 2012
Netherlands AntillesPresentNativeUSDA-ARS, 2012Saba, St Eustatius
NicaraguaPresentNativeUSDA-ARS, 2012
PanamaPresentNativeUSDA-ARS, 2012
Puerto RicoPresentNativeUSDA-ARS, 2012
Saint Kitts and NevisPresentNativeUSDA-ARS, 2012
Saint LuciaPresentNativeUSDA-ARS, 2012
Saint Vincent and the GrenadinesPresentNativeUSDA-ARS, 2012St Vincent
United States Virgin IslandsPresentNativeGBIF, 2012

South America

ArgentinaPresentNativeUSDA-ARS, 2012
BoliviaWidespreadNativeUSDA-ARS, 2012
BrazilWidespreadNativeUSDA-ARS, 2012
-AlagoasPresentNativeLorenzi, 1982
-BahiaPresentNativeLorenzi, 1982
-CearaPresentNativeLorenzi, 1982
-GoiasPresentNativeLorenzi, 1982
-Mato GrossoPresentNativeLorenzi, 1982
-Mato Grosso do SulPresentNativeLorenzi, 1982
-Minas GeraisPresentNativeLorenzi, 1982
-ParaibaPresentNativeLorenzi, 1982
-ParanaPresentNativeLorenzi, 1982
-PernambucoPresentNativeLorenzi, 1982
-Rio de JaneiroPresentNativeLorenzi, 1982
-Rio Grande do NortePresentNativeLorenzi, 1982
-Rio Grande do SulPresentNativeLorenzi, 1982
-Santa CatarinaPresentNativeLorenzi, 1982
-Sao PauloPresentNativeLorenzi, 1982
-TocantinsPresentNativeLorenzi, 1982
ColombiaPresentNativeUSDA-ARS, 2012
EcuadorPresentNativeUSDA-ARS, 2012
French GuianaPresentNativeUSDA-ARS, 2012
GuyanaPresentNativeUSDA-ARS, 2012
ParaguayWidespreadNativeUSDA-ARS, 2012
PeruPresentNativeUSDA-ARS, 2012
SurinamePresentNativeUSDA-ARS, 2012
UruguayPresentNativeUSDA-ARS, 2012
VenezuelaPresentNativeUSDA-ARS, 2012

Oceania

FijiPresentIntroducedPIER, 2012
GuamPresentIntroducedPIER, 2012
Marshall IslandsPresentIntroduced Invasive PIER, 2012Ralik Chain
Northern Mariana IslandsPresentIntroduced Invasive PIER, 2012Saipan, Tinian Islands
Papua New GuineaPresentIntroduced Invasive PIER, 2012
Solomon IslandsPresentIntroducedPIER, 2012
US Minor Outlying IslandsPresentIntroducedPIER, 2012Midway Atoll
VanuatuPresentIntroducedPIER, 2012
Wake IslandPresentIntroduced Invasive PIER, 2012

History of Introduction and Spread

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No information has been found on the history of introduction to Asia and the Pacific and it is unclear how the introductions have occurred other than, presumably, by contamination of the seed of pasture species. Earliest collections recorded by GBIF (2012) indicate presence in Hawaii by 1925, Marshall and Northern Mariana Islands by 1946 and Papua New Guinea by 1959.

Risk of Introduction

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D. insularis is not traded as either a forage crop or an ornamental suggesting that the risk of introduction should be low.

Habitat

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In its native areas in South America it is a plant of low altitude swamps, pastures, railway tracks, roadsides, pastures and disturbed forest. Generally in moist conditions but also occurring in some drier situations. In Hawaii, USA, it is "naturalized in abandoned fields, pastures, disturbed sites, and along roadsides, 0-340 m.” In New Guinea, it is "a weed of grazing land, headlands and roadsides; not a serious problem in cultivation" (PIER, 2012).

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Terrestrial
 
Terrestrial – ManagedCultivated / agricultural land Secondary/tolerated habitat
Managed forests, plantations and orchards Secondary/tolerated habitat
Managed grasslands (grazing systems) Principal habitat
Disturbed areas Principal habitat
Rail / roadsides Principal habitat
Urban / peri-urban areas Secondary/tolerated habitat
Terrestrial ‑ Natural / Semi-naturalNatural forests Secondary/tolerated habitat
Natural grasslands Principal habitat
Wetlands Secondary/tolerated habitat

Hosts/Species Affected

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D. insularis affects pastures and a wide range of perennial crops including coffee, tea, citrus, pineapple, forest nurseries, etc.; also cotton and maize.

Biology and Ecology

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Genetics

The chromosome number is reported to be 2n=36 (Gould and Soderstrom, 1967).

Reproductive Biology

Reproduction is almost totally from prolific seed production though there may be regeneration from cut culm fragments and from the rhizomatous shoot bases. Mondo et al. (2010) found the best temperatures for germination were 20-35°C. They also concluded that D. insularis did not require light for germination. However, Pyon (1976) obtained best germination under light. Germination in complete darkness was poor except at 25-35°C alternating temperature. Optimum constant temperature was 30°C.

Physiology and Phenology

Smith and Brown (1973) confirm that D. insularis has Krantz anatomy and C4 physiology.

D. insularis was capable of emerging from a maximum depth of 5 cm but percentage emergence was greatly reduced at sowing depths >3 cm (Pyon et al., 1977).

In a study by Machado et al. (2006), height, leaf area and dry matter were evaluated at 7-day intervals between 14 and 112 days after emergence (DAE). The highest leaf area and dry matter were recorded at 98 and 105 DAE, respectively. Leaves showed greater participation in total dry matter accumulation, followed by roots + rhizome, up to 105 DAE. Dry matter accumulation was slow up to 45 DAE and then increased due to rhizome formation. Relative growth rate decreased with time due to higher photo-assimilate accumulation.

Plants growing from rhizomatous shoot bases have high stomatal index and a large number of stomata per mm2, thick adaxial and abaxial epidermis faces, and a thick leaf lamina. The intense colouration in the rhizomes treated with lugol indicated the presence of a great amount of starch, regardless of the origin of the material (Machado et al., 2008).

Flowering in D. insularis was not affected by day-length (Pyon et al., 1977).

Environmental Requirements

D. insularis is a plant of the tropics and sub-tropics, associated in USA with USDA hardiness zones 9-11, i.e. average minimum winter temperatures above 20°C. It certainly survives under significantly cooler conditions but is susceptible to frost.

Climate

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ClimateStatusDescriptionRemark
Af - Tropical rainforest climate Preferred > 60mm precipitation per month
Am - Tropical monsoon climate Preferred Tropical monsoon climate ( < 60mm precipitation driest month but > (100 - [total annual precipitation(mm}/25]))
As - Tropical savanna climate with dry summer Tolerated < 60mm precipitation driest month (in summer) and < (100 - [total annual precipitation{mm}/25])
Aw - Tropical wet and dry savanna climate Preferred < 60mm precipitation driest month (in winter) and < (100 - [total annual precipitation{mm}/25])
Cf - Warm temperate climate, wet all year Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, wet all year
Cs - Warm temperate climate with dry summer Tolerated Warm average temp. > 10°C, Cold average temp. > 0°C, dry summers
Cw - Warm temperate climate with dry winter Tolerated Warm temperate climate with dry winter (Warm average temp. > 10°C, Cold average temp. > 0°C, dry winters)

Air Temperature

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Parameter Lower limit Upper limit
Mean annual temperature (ºC) 13
Mean minimum temperature of coldest month (ºC) -1

Rainfall

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ParameterLower limitUpper limitDescription
Dry season duration07number of consecutive months with <40 mm rainfall

Natural enemies

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Natural enemyTypeLife stagesSpecificityReferencesBiological control inBiological control on
Maize chlorotic mottle virus Pathogen
Maize dwarf mosaic virus Pathogen
Mocis latipes Herbivore
Radopholus similis Parasite
Sporisorium panici-leucophaei Pathogen
Xanthomonas citri Pathogen

Notes on Natural Enemies

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D. insularis is affected by the smut Sporisorium panici-leucophaei in North, Central and South America (Perez et al., 2002). A fungal endophyte, Pseudocercosporella trichachnicola occurs in the USA (White and Morrow, 1990). The canker bacterium Xanthomonas citri occurs in Brazil (Pereira et al., 1976). It has also tested positive for the maize viruses MDMV-A [Maize dwarf mosaic virus strain A] and MCMV [Maize chlorotic mosaic virus] in Hawaii, USA (Jiang et al., 1992).

In Brazil, the noctuid Mocis latipes  and the nematode Radopholus similis occur on D. insularis (Silva and Neves, 1984 and Zem and Lordello, 1983, respectively).

Means of Movement and Dispersal

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Natural Dispersal (non-biotic)

Natural dispersal occurs by movement of seed with wind or water.

Vector Transmission (biotic)

Local movement by livestock internally or externally is likely but there is no documentation of this.

Accidental Introduction

There is little documentation of how D. insularis has come to be introduced so widely. It has not been promoted as a forage grass, so it is presumed that introduction has occurred by accidental contamination of seed lots of more desirable pasture grass species.

Intentional Introduction

No evidence for deliberate introduction has been seen.

Plant Trade

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Plant parts liable to carry the pest in trade/transportPest stagesBorne internallyBorne externallyVisibility of pest or symptoms
Growing medium accompanying plants seeds
True seeds (inc. grain) seeds Yes

Impact Summary

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CategoryImpact
Economic/livelihood Negative
Environment (generally) Negative

Economic Impact

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No crop-loss data are available but it is clearly regarded as an economic problem in a wide range of crops, especially in Brazil and Paraguay and particularly in non-conventional sugarcane (Arevalo and Bertoncini, 2005) and also in no-till coffee, manila hemp (Musa textilis), citrus, Eucalyptus grandis, passion fruit, rubber, guarana (Paullinia cupana), Japanese plums (Prunus salicina), cotton and pineapple.

Environmental Impact

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Impact on Habitats

D. insularis is seen as an undesirable dominant grass where natural forest has been replaced by derived savannah in lowland Bolivia (Veldman and Putz, 2011).

D. insularis is among species displacing Hawaiian Pili grass (Heteropogon contortus) in the Hawaiian Islands (Daehler and Goergen, 2005).

Impact on Biodiversity

In Hawaii, D. insularis is among species considered to be threatening a number of native species including Scaevola coriacea, Silene lanceolata, Schiedea kealiae, Sesbania tomentosa and Panicum fauriei var. carteri [Panicum fauriei] (US Fish and Wildlife Service, 2010 a,b,c,d; 2011).

Threatened Species

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Threatened SpeciesConservation StatusWhere ThreatenedMechanismReferencesNotes
Panicum fauriei var. carteri (Carter's panicgrass)NatureServe NatureServe; USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - shadingUS Fish and Wildlife Service, 2011
Scaevola coriacea (dwarf naupaka)NatureServe NatureServe; USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - shadingUS Fish and Wildlife Service, 2010a
Schiedea kealiae (Waianae Range schiedea)CR (IUCN red list: Critically endangered) CR (IUCN red list: Critically endangered); USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - shadingUS Fish and Wildlife Service, 2010c
Sesbania tomentosaNational list(s) National list(s); USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - shadingUS Fish and Wildlife Service, 2010d
Silene lanceolata (Kauai catchfly)USA ESA listing as endangered species USA ESA listing as endangered speciesHawaiiCompetition - shadingUS Fish and Wildlife Service, 2010b

Risk and Impact Factors

Top of page Invasiveness
  • Invasive in its native range
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Pioneering in disturbed areas
  • Fast growing
  • Has high reproductive potential
  • Reproduces asexually
Impact outcomes
  • Ecosystem change/ habitat alteration
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts agriculture
  • Negatively impacts forestry
  • Reduced native biodiversity
  • Threat to/ loss of endangered species
  • Threat to/ loss of native species
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - shading
Likelihood of entry/control
  • Difficult to identify/detect as a commodity contaminant
  • Difficult/costly to control

Uses

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D. insularis is used in traditional medicine for bladder and kidney inflammation in Cuba; also as a diuretic and for dressing contusions and wounds;  in Paraguay it is used with other herbs in abortive medicine (Delfeld, 2012). Extracts of D. insularis are also effective in the in vitro treatment of gastrointestinal nematodes of goats (Aleida et al., 2003).

Panicles may be used to decorate altars and homes in Central America and Puerto Rico, and the stems for weaving hats (Delfeld, 2012).

It is not considered good as forage in Mexico (Ramirez et al., 2009). Some sources say it is grazed readily by cattle. Others suggest it is unpalatable to cattle, e.g. in Argentina and in Papua New Guinea (Chadhokar, 1976).

Similarities to Other Species/Conditions

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Among closely related species in Mexico, D. insularis is distinguished from other species having sterile lemmas with glabrous veins by being pilose between the central veins of the lemma and having hairs on the sides of the central veins tawny or yellow to whitish. In Digitaria patens and D. californica, the space between the central veins is glabrous and the hairs to the sides are white to purplish (Sánchez-Ken, 2012). In Arizona, USA, D. cognata differs from D. insularis in having felty pubescence near the base of the stems (Austin, 2010).

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 and Sanitary Measures

D. insularis can be crowded out through competition with buffel grass (Cenchrus ciliaris) and Guinea grass (Panicum maximum) under natural conditions in Hawaii, USA (Pyon, 1976). D. insularis growth is slow up to 45 days after emergence, but increased from 45 to 105 days, suggesting the possibility of good cultural control by crops that have fast initial growth and large leaf area (Machado et al., 2006).

Physical/Mechanical Control

Seedlings are readily controlled by cultivation but not so once the plants are established with rhizomes.

Chemical Control

Glyphosate has been used as the standard herbicide in plantation crops and in glyphosate-resistant crops such as soyabean and cotton, but glyphosate-resistance has developed in repeatedly glyphosate-treated soyabean in Brazil and in Paraquay (Cerdeira et al., 2011). Resistance factors of 2.3 and 3.9 have been identified in Brazil apparently associated with shikimic acid metabolism, where the susceptible biotype accumulated 3.3 to 5.7 times more shikimic acid than the resistant biotypes (Carvalho et al., 2011). Glyphosate was degraded to aminomethylphosphonic acid (AMPA), glyoxylate and sarcosine by over 90% in resistant biotypes, whereas only 11% was degraded in the susceptible biotype. Two amino acid changes were found at positions 182 and 310 in EPSPS (5-enolpyruvylshikimate-3-phosphate synthase), consisting of a proline to threonine and a tyrosine to cysteine substitution, respectively, in resistant biotypes. Therefore, absorption, translocation, metabolism and gene mutation play an important role in the D. insularis glyphosate resistance (Carvalho et al., 2012).

Irrespective of the development of resistance, glyphosate may give poor results on well-established plants with rhizomes. Activity of glyphosate may be enhanced by the addition of urea and/or ammonium sulfate (Carvalho et al., 2010). Improved results have also been obtained by combinations with sethoxydim (Parreira et al., 2010), with chlorimuron-ethyl (Carvalho et al., 2009), with quizalofop (Correia and Durigan, 2009); also with fluazifop, or its application in sequence with diuron plus paraquat (Procopio et al., 2006; Correira et al., 2010).

To minimize the development of glyphosate resistance the following are suggested: (a) rotation of glyphosate-resistant soyabeans with conventional soyabeans; b) avoidance of lower than recommended glyphosate rates; (c) keeping soil covered with a crop or legume at intercrop intervals; (d) keeping machinery free of weed seeds; and (d) use of a pre-plant non-selective herbicide plus residuals to eliminate early weed interference with the crop and to minimize escapes from later applications of glyphosate due to natural resistance of older weeds and/or incomplete glyphosate coverage (Cerdeira et al., 2011).

Other herbicides to have proved effective include fluazifop-P-butyl in lucerne (Silva et al., 2003); sethoxydim plus oil, or fluazifop plus surfactant in rubber (Azevedo et al., 1999); and nicosulfuron in maize (Timossi, 2009). In pastures it has been controlled by spot spraying with dalapon (Chadhokar, 1976).

Gaps in Knowledge/Research Needs

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There is a lack of basic biological information on D. insularis, including the longevity of seeds in the soil, longevity of established plants; also means of non-chemical control.

References

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Almeida MÂO de; Botura MB; Santos MM dos; Almeida GN; Domingues LF; Costa SL; Batatinha MJM, 2003. Effects of aqueous extracts of Cymbopogon citratus and Digitaria insularis leaves on larval cultures of gastrointestinal nematodes of goats. (Efeitos dos extratos aquosos de folhas de Cymbopogon citratus (DC.) Stapf (Capim-santo) e de Digitaria insularis (L.) Fedde (Capim-açu) sobre cultivos de larvas de nematóides gastrintestinais de caprinos.) Revista Brasileira de Parasitologia Veterinária, 12(3):125-129.

Arévalo RA; Bertoncini EI, 2005. Sustainable weed management in Saccharum spp. (Manejo sostenible de especies de malezas en Saccharum spp.) In: XVII Congreso de la Asociación Latinoamericana de Malezas (ALAM) I Congreso Iberoamericano de Ciencia de las Malezas, IV Congreso Nacional de Ciencia de Malezas, Matanzas, Cuba, 8 al 11 de noviembre del 2005. Matanzas, Cuba: Asociación Latinoamericana de Malezas (ALAM), 91-106.

Austin DF, 2010. Baboquivari Mountain Plants: Identification, Ecology and Ethnobotany. Tucson, Arizona, USA: University of Arizona Press, 337 pp.

Azevedo DMP de; Roman ES; Lisboa S de M, 1999. Control of weed grass species in rubber plantations. (Controle de gramíneas em cultivo de seringueira.) Revista de Ciências Agrárias, No. 31:21-28.

Carvalho LB de; Alves PL da CA; González-Torralva F; Cruz-Hipolito HE; Rojano-Delgado AM; Prado R de; Gil-Humanes J; Barro F; Luque de Castro MD, 2012. Pool of resistance mechanisms to glyphosate in Digitaria insularis. Journal of Agricultural and Food Chemistry, 60(2):615-622. http://pubs.acs.org/doi/abs/10.1021/jf204089d

Carvalho LB de; Cruz-Hipolito H; González-Torralva F; Alves PL da CA; Christoffoleti PJ; Prado R de, 2011. Detection of sourgrass (Digitaria insularis) biotypes resistant to glyphosate in Brazil. Weed Science, 59(2):171-176. http://wssajournals.org/doi/abs/10.1614/WS-D-10-00113.1

Carvalho LB; Scherer LC; Lucio FR; Alves PLCA, 2009. Effects of desiccation with glyphosate and chlorimuron-ethyl on weed community and soybean yield. (Efeitos da dessecação com glyphosate e chlorimuron-ethyl na comunidade infestante e na produtividade da soja.) Planta Daninha, 27(Especial):1025-1034. http://www.scielo.br/pd

Carvalho SJP; Dias ACR; Shiomi GM; Christoffoleti PJ, 2010. Simultaneous addition of ammonium sulfate and urea to glyphosate spray solution. (Adição simultânea de sulfato de amônio e ureia à calda de pulverização do herbicida glyphosate.) Planta Daninha, 28(3):575-584. http://www.scielo.br/pdf/pd/v28n3/14.pdf

Cerdeira AL; Gazziero DLP; Duke SO; Matallo MB, 2011. Agricultural impacts of glyphosate-resistant soybean cultivation in South America. Journal of Agricultural and Food Chemistry, 59(11):5799-5807. http://pubs.acs.org/doi/abs/10.1021/jf102652y

Chadhokar PA, 1976. Control of Digitaria insularis (L.) Mez in tropical pastures. PANS, 22(1):79-85.

Chadhokar PA, 1978. Weed problems of grazing lands and control of some problem weeds in the Markham Valley of Papua New Guinea. PANS, 24(1):63-66

Correia NM; Durigan JC, 2009. Chemical management of adult Digitaria insularis with glyphosate alone and mixture with chlorimuron-ethyl or quizalofop-p-tefuril in a no-tillage field. (Manejo químico de plantas adultas de Digitaria insularis com glyphosate isolado e em mistura com chlorimuronethyl ou quizalofop-p-tefuril em área de plantio direto.) Bragantia, 68(3):689-697. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0006-87052009000300016&lng=en&nrm=iso&tlng=pt

Correia NM; Leite GJ; Garcia LD, 2010. Response of different Digitaria insularis populations to glyphosate. (Resposta de diferentes populações de Digitaria insularis ao herbicida glyphosate.) Planta Daninha, 28(4):769-776. http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-83582010000400009&lng=en&nrm=iso&tlng=pt

Daehler CC; Goergen EM, 2005. Experimental restoration of an indigenous Hawaiian grassland after invasion by Buffel grass (Cenchrus ciliaris). Restoration Ecology, 13(2):380-389. http://www3.interscience.wiley.com/cgi-bin/fulltext/118708058/HTMLSTART

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03/12/12 Original text by:

Chris Parker, Consultant, UK

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