Sorghum halepense (L.) Pers., Poaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score: 25 (Go to the risk assessment)

Other Latin names:  Andropogon halepensis (L.) Brot.

Common name(s): [more details]

Bikol: aroró

Chinese: shi mao

English: Aleppo grass, Aleppo milletgrass, alwyn grass, Johnson grass

French: herbe d'Alep, herbe de Cuba, sorgho, sorgho d'Alep

Ifugao: baku

Palauan: mbangarnuis

Spanish: cañota, grama china, grama china, hierba Johnson, milloca, pasto Johnson, sorgo de Aleppo, sorgo maleza, zacate johnson

Tagalog: batad-batádan, ngigai

Habit:  grass

Description:  "Perennial [grass] with strong rhizomes; culms erect, to 1.5 m tall; nodes with short pubescence; sheaths glabrous; ligule ciliate-membranous, 2 mm long; blades elongate, usually 1-1.5 cm wide, the midrib prominent; panicles 15-25 cm long, branches ascending; spikelets 5 mm long, acute; first glume hard; fertile lemma awned or awnless, awn if present 1 cm long or less" (Stone, 1970; p. 239).

"Habit: Perennial. Rhizomes elongated; scaly. Culms erect, or geniculately ascending, or decumbent; 50-300 cm long. Culm-nodes pubescent. Leaves cauline. Ligule a ciliolate membrane. Leaf-blades 20-90 cm long; 5-40 mm wide. Leaf-blade margins scaberulous. Inflorescence: Inflorescence a panicle with branches tipped by a raceme. Panicle open; lanceolate, or pyramidal; 10-55 cm long; 3-25 cm wide. Primary panicle branches whorled at most nodes; moderately divided. Racemes 1.2-2.5 cm long; bearing few fertile spikelets; bearing 1-5 fertile spikelets on each. Rhachis fragile at the nodes; ciliate on margins. Rhachis internodes filiform. Rhachis internode tip transverse; cupuliform. Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels filiform; ciliate. Sterile spikelets: Companion sterile spikelets well-developed; male; lanceolate; 4.5-6.5 mm long; as long as fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; 5 -veined; muticous. Companion sterile spikelet lemmas enclosed by glumes. Fertile spikelets: Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets elliptic; dorsally compressed; 4.5-5(-5.5) mm long; falling entire; deciduous with accessory branch structures. Spikelet callus pubescent; base obtuse. Glumles: Glumes dissimilar; with lower wider than upper; exceeding apex of florets; firmer than fertile lemma. Lower glume elliptic; 1 times length of spikelet; coriaceous; pallid, or dark brown, or red, or purple, or black; 2-keeled; keeled above. Lower glume surface glabrous, or pubescent. Lower glume apex dentate; 3-fid. Upper glume ovate; coriaceous; without keels. Upper glume surface glabrous, or pubescent. Florets: Basal sterile florets barren; without significant palea. Lemma of lower sterile floret elliptic; 0.8 times length of spikelet; hyaline; 2-veined; ciliolate on margins. Fertile lemma elliptic; 2-2.5 mm long; hyaline; 1-veined. Lemma margins ciliate. Lemma apex entire, or dentate; 2 -fid; muticous, or awned; 1 -awned. Principal lemma awn from a sinus; geniculate; 10-16 mm long overall; with twisted column. Column of lemma awn pubescent; hairy on the spiral. Palea present. Flower: Lodicules 2; ciliate" (GrassBase).

Habitat/ecology:  "It seems best adapted to the warm, humid, summer-rainfall areas in the subtropics and not so well adapted to areas which are strictly tropical.  The species can grow on a variety of sites; on arable land, waste places, roadsides, and field  borders.  It occurs extensively along irrigated canals and at the edges of irrigated fields,  Its general distribution in these areas is the result of water movement of the seeds, which readilly fall from the head when mature"  (Holm et al., 1977; pp. 54, 57).  "Plants develop long rhizomes bearing buds which germinate readily. Rhizome growth of Johnson grass is more abundant than the shoot growth (Oyer et al., 1959; La O et al., 1993b) and in some cases rhizome fresh weight reaches 90% of the whole developed Johnson grass plant (Horowitz, 1972b). Apical dominance is broken with rhizome fragmentation, which consistently stimulates lateral bud germination (Hull, 1968) and each bud produces one shoot" (Oyer et al. 1959).

"Common to abundant on roadsides and in waste places, and occasionally in crops, particularly those near roadsides" (Whistler, 1983; p. 95). In Hawai‘i, "naturalized in mesic to wet, disturbed sites, 10-520 M"  (Wagner et al., 1999; p. 1594).  In Fiji, "a widespread and serious weed of cultivation and was declared a noxious weed in 1947"  (Smith, 1979; pp. 374-375). In New Caledonia, "largement répandu et très commun comme mauvaise herbe" (MacKee, 1994; p. 62).

Propagation:  Reproduction is by seed and rhizome production. It grows and develops intensively in warm habitats, with air temperatures above 15C (Horowitz, 1972a).

Rhizomes are distributed mainly in the top 20 cm of the soil profile. Most are located in the first 15 cm, but up to 10% are found below 30 cm (Horowitz, 1972b; McWhorter, 1972). Rhizome initiation usually takes place a month or 45 days after Johnson grass emergence and coincides with tillering or the 6-7 leaf stage of shoot growth (Oyer et al., 1959; Anderson et al., 1960; Horowitz 1972a; La O et al., 1993a). This process is commonly faster with plants developing from long rhizomes.

Seed production is variable and dependent on several environmental factors. High seed production is found in plants with high tiller production. Production of seed may vary from 540 to 1440 kg/ha (McWhorter, 1973, 1989), but not all of them are able to germinate immediately after ripening. The optimal air temperature for seed germination is within the range 25-30oC (Horowitz, 1972a). The seeds can remain viable in soil for periods of up to 6 years (Leguizamón, 1986). In Mississippi (U.S.A.), germination of Johnson grass decreased from 62% after being buried for 2.5 year to 37% after 5.5 year (Egley, 1977; Egley and Chandler 1983).

Vigorous growth requires high light intensity (McWhorter and Jordan, 1976) and photoperiods of 12.5 hours are optimal for Johnson grass growth and development (Sakri and Hull, 1968).

Native range:  Southeastern Europe, now widespread. It is present in many countries of the world. It prevails in hot climatic conditions and tends to be more productive during the rainy season in tropical areas (La O et al., 1993b). Supposedly introduced to Guam from Samoa.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
American Samoa American Samoa Islands	American Samoa Islands		Swarbrick, John T. (1997) (p. 97) There is some question as to whether or not the species in Western Polynesia is S. halepense. Whistler (1988) identifies it as S. sudanense (Piper) Stapf.
Chile (offshore islands) Rapa Nui (Easter) Island	Rapa Nui (Easter) Island (Isla de Pasqua)	introduced invasive	Meyer, Jean-Yves (2008) (p. 29)
Chile (offshore islands) Rapa Nui (Easter) Island	Rapa Nui (Easter) Island (Isla de Pasqua)	introduced	Skottsberg, Carl (1953) (p. 80)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive	Atkinson, Rachel/Sawyer, John (2011)
Chile (offshore islands) Juan Fernández Islands	Isla Más a Tierra (Robinson Crusoe Island)	introduced invasive cultivated	Danton, Philippe/Perrier, Christophe/Martinez Reyes, Guido (2006) (pp. 499, 545, 558) Voucher cited: Danton I(5/91)1452. "En RC, lo encontramos fuera de los jardines en una calle del pueblo de San Juan Bautista.  Es una especie agresiva, probablemente de introducción reciente, que serí mejor eliminar rápidamente".
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Rota Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 60) Also f. muticum
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Rota Island	introduced invasive	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 96-98) f. halepense; voucher cited: Fosberg 31860 (US, BISH, POM); f. muticum (Hack.) Hubb.; voucher cited: Evans 2002 (US, BISH, A, POM, BRI, L)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Rota Island		Bishop Museum (Honolulu) (1966) (voucher ID: BISH 588718) Taxon name on voucher: Sorghum halepense (L.) Pers.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Rota Island		Bishop Museum (Honolulu) (1950) (voucher ID: BISH 588728) Taxon name on voucher: Sorghum halepense (L.) Pers.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Saipan Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 60) Also f. muticum and var. propinquum.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Saipan Island	introduced invasive	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 96-98) f. halepense; voucher cited: Hosaka 2901 (US, BISH); f. muticum (Hack.) Hubb.; vouchers cited: Fosberg 31266 (US, BISH), Fosberg 25216 (US, BISH, A, BRI, K); var. propinquum (Kunth) Ohwi; vouchers cited: Kanehira 911 (FU), Kanehira 965 (FU), Kanehira 1002 (FU), Kanehira & Hatusima 4266 (FU)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Saipan Island		Bishop Museum (Honolulu) (1930) (voucher ID: BISH 126886) Taxon name on voucher: Sorghum halepense (L.) Pers.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Saipan Island		Bishop Museum (Honolulu) (1986) (voucher ID: BISH 572170) Taxon name on voucher: Sorghum halepense (L.) Pers.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Saipan Island		Bishop Museum (Honolulu) (1946) (voucher ID: BISH 588726) Taxon name on voucher: Sorghum halepense (L.) Pers.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Saipan Island		Bishop Museum (Honolulu) (1950) (voucher ID: BISH 588730) Taxon name on voucher: Sorghum halepense (L.) Pers.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Saipan Island		Bishop Museum (Honolulu) (1946) (voucher ID: BISH 588733) Taxon name on voucher: Sorghum halepense (L.) Pers.
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 60) f. muticum
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island	introduced invasive	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 96-98) f. muticum (Hack.) Hubb.; voucher cited: Hosaka 2833 (US, BISH, MO)
Commonwealth of the Northern Mariana Islands (US) Northern Mariana Islands	Tinian Island		Bishop Museum (Honolulu) (1946) (voucher ID: BISH 588731) Taxon name on voucher: Sorghum halepense (L.) Pers.
Cook Islands Southern Cook Islands	Mangaia Island		Bishop Museum (Honolulu) (1928) (voucher ID: BISH 126846) Taxon name on voucher: Sorghum halepense (L.) Pers.
Federated States of Micronesia Chuuk Islands	Weno (Moen) Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 60) f. muticum
Federated States of Micronesia Chuuk Islands	Weno (Moen) Island		Bishop Museum (Honolulu) (1980) (voucher ID: BISH 588720) Taxon name on voucher: Sorghum halepense (L.) Pers.
Federated States of Micronesia Pohnpei Islands	Pohnpei Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 60) f. muticum
Federated States of Micronesia Pohnpei Islands	Pohnpei Island		Glassman, S. F. (1952) (p. 133) Voucher cited: Glassman 2909 (US)
Federated States of Micronesia Pohnpei Islands	Pohnpei Island	introduced invasive	Herrera, Katherine/Lorence, David H./Flynn, Timothy/Balick, Michael J. (2010) (p. 61) Vouchers cited: B.Ekiek 121 (NY, PTBG), T.W. Flynn 6227 (K, PTBG) Naturalized
Federated States of Micronesia Pohnpei Islands	Pohnpei Island	introduced invasive	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 96-98) f. muticum (Hack.) Hubb.; vouchers cited: Glassman 2909 (US), Fosberg 58563 (US, BISH, POM, NY)
Federated States of Micronesia Pohnpei Islands	Pohnpei Island		Bishop Museum (Honolulu) (1949) (voucher ID: BISH 126884) Taxon name on voucher: Sorghum halepense (L.) Pers.
Federated States of Micronesia Pohnpei Islands	Pohnpei Island		Bishop Museum (Honolulu) (1978) (voucher ID: BISH 438254) Taxon name on voucher: Sorghum halepense (L.) Pers.
Federated States of Micronesia Pohnpei Islands	Pohnpei Island		Bishop Museum (Honolulu) (1987) (voucher ID: BISH 511181) Taxon name on voucher: Sorghum halepense (L.) Pers.
Fiji Fiji Islands	Vanua Levu Island	introduced invasive	Smith, Albert C. (1979) (pp. 374-375) Vouchers cited: DA 8732, DA 10452
Fiji Fiji Islands	Vanua Levu Island		Bishop Museum (Honolulu) (1954) (voucher ID: BISH 31630) Taxon name on voucher: Sorghum halepense (L.) Pers.
Fiji Fiji Islands	Viti Levu Island	introduced invasive	Smith, Albert C. (1979) (pp. 374-375) Vouchers cited: DA 2519, DA 10407, DA 10419, DA 8188, DA 10811; f. muticum: DA 2519, DA 8539, DA 10751, DA 10438
Fiji Fiji Islands	Viti Levu Island		Bishop Museum (Honolulu) (1957) (voucher ID: BISH 31659) Taxon name on voucher: Sorghum halepense (L.) Pers.
French Polynesia Gambier Islands	Mangareva (Gambier) Island	introduced	St. John, Harold (1988) (p. 8) Voucher cited: Agassiz 92 (GH)
French Polynesia Marquesas Islands	Hiva Oa Island	introduced invasive	Lorence, David H./Wagner, Warren L. (2008)
French Polynesia Society Islands	Bora Bora Island	introduced	Fosberg, F. R. (1997) (p. 106)
French Polynesia Society Islands	Raiatea (Havai) Island	introduced invasive	Welsh, S. L. (1998) (p. 345) Voucher cited: BRY 26356
French Polynesia Society Islands	Tahiti Island	introduced invasive	Welsh, S. L. (1998) (p. 345) Voucher cited: BRY 25989
Guam Guam Island	Guam Island	introduced invasive	Stone, Benjamin C. (1970) (p. 239) Forma mutica C.E. Hubbard
Guam Guam Island	Guam Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 60) f. muticum
Guam Guam Island	Guam Island	introduced invasive	Meyer, Jean-Yves (2000) (p. 95)
Guam Guam Island	Guam Island	introduced invasive	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 96-98) f. muticum (Hack.) Hubb.; vouchers cited: McGregor 491 (US), Pedrus 43 (US), Fosberg 39240 (US, BISH, POM, MO, CANB), Stone 4054 (US, GUAM)
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1911) (voucher ID: BISH 126883) Taxon name on voucher: Sorghum halepense (L.) Pers.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1918) (voucher ID: BISH 126887) Taxon name on voucher: Sorghum halepense (L.) Pers.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1918) (voucher ID: BISH 126889) Taxon name on voucher: Sorghum halepense (L.) Pers.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1966) (voucher ID: BISH 588719) Taxon name on voucher: Sorghum halepense (L.) Pers.
Guam Guam Island	Guam Island		Bishop Museum (Honolulu) (1957) (voucher ID: BISH 588729) Taxon name on voucher: Sorghum halepense (L.) Pers.
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1594-1595)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1594-1595)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1594-1595)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1594-1595)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Wagner, Warren L./Herbst, Derral R./Sohmer, S. H. (1999) (pp. 1594-1595) Voucher cited: Forbes 1331 (BISH)
Japan (offshore islands) Bonin (Ogasawara) Islands	Bonin (Ogasawara) Islands	introduced	Kato, Hidetoshi (2007) Also f. muticum (Hack.) C.E.Hubb.
Marshall Islands Marshall Islands	Marshall Islands		Waterhouse, D. F. (1997) (p. 65)
New Caledonia Îles Loyauté (Loyalte Islands)	Îles Loyauté (Loyalty Islands)	introduced invasive cultivated	Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 381) Largement répandue et très commune comme mauvaise herbe.
New Caledonia Îles Loyauté (Loyalte Islands)	Îles Loyauté (Loyalty Islands)	introduced invasive	MacKee, H. S. (1994) (p. 62)
New Caledonia New Caledonia Archipelago	Île Belep	introduced invasive cultivated	Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 381) Largement répandue et très commune comme mauvaise herbe.
New Caledonia New Caledonia Archipelago	Île Belep	introduced invasive	MacKee, H. S. (1994) (p. 62)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive cultivated	Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 381) Largement répandue et très commune comme mauvaise herbe.
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	MacKee, H. S. (1994) (p. 62)
New Caledonia New Caledonia Archipelago	Île des Pins (Isle of Pines)	introduced invasive cultivated	Gargominy, Oliver/Bouchet, Philipe/Pascal, Michel/Jaffre, Tanguy/Tourneu, Jean-Christophe (1996) (p. 381) Largement répandue et très commune comme mauvaise herbe.
New Caledonia New Caledonia Archipelago	Île des Pins (Isle of Pines)	introduced invasive	MacKee, H. S. (1994) (p. 62) Voucher cited: Germain s.n.
Palau Palau (main island group)	Babeldaob Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 86)
Palau Palau (main island group)	Babeldaob Island	introduced invasive	Space, James C./Lorence, David H./LaRosa, Anne Marie (2009) (p. 20) Voucher: Lorence 9889 (PTBG, BNM, BISH, NY, US)
Palau Palau (main island group)	Babeldaob Island		Bishop Museum (Honolulu) (1996) (voucher ID: BISH 151023) Taxon name on voucher: Sorghum halepense (L.) Pers.
Palau Palau (main island group)	Babeldaob Island		Beleu National Museum (Republic of Palau. Koror.) (1996) (voucher ID: BNM 26386) Taxon name on voucher: Sorghum halepense (L.) Pers.
Palau Palau (main island group)	Babeldaob Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (2008) (voucher ID: PTBG 182) Taxon name on voucher: Sorghum halepense (L.) Pers.
Palau Palau (main island group)	Koror Island	introduced	Fosberg, F. R./Sachet, Marie-Hélène/Oliver, Royce (1987) (p. 60) f. muticum and var. propinquum
Palau Palau (main island group)	Koror Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 82)
Palau Palau (main island group)	Koror Island	introduced invasive	Fosberg, F. R./Sachet, M.-H. (1982) (pp. 96-98) f. muticum (Hack.) Hubb.; vouchers cited: Blackburn E 16 (US), STone 4585 (GUAM), Fosberg 32321 (US, BISH); var. propinquum (Kunth) Ohwi; voucher cited: Kanehira 210 (FU)
Palau Palau (main island group)	Koror Island		Bishop Museum (Honolulu) (1950) (voucher ID: BISH 588732) Taxon name on voucher: Sorghum halepense (L.) Pers.
Palau Palau (main island group)	Koror Island		Beleu National Museum (Republic of Palau. Koror.) (1966) (voucher ID: BNM 1074) Taxon name on voucher: Sorghum halepense (L.) Pers.
Palau Palau (main island group)	Malakal Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 82)
Palau Palau (main island group)	Malakal Island		Beleu National Museum (Republic of Palau. Koror.) (1981) (voucher ID: BNM 3129) Taxon name on voucher: Sorghum halepense f. muticum (Hack.) Hubb.
Palau Palau (main island group)	Ngerkebesang Island	introduced invasive	Space, James C./Waterhouse, Barbara/Miles, Joel E./Tiobech, Joseph/Rengulbai, Kashgar (2003) (p. 82)
Papua New Guinea Papua New Guinea (eastern New Guinea Island)	Papua New Guinea (eastern New Guinea Island)		Waterhouse, D. F. (1997) (p. 65)
Philippines Philippine Islands	Philippine Islands	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 61)
Philippines Philippine Islands	Philippine Islands		Merrill, Elmer D. (1925) (p. 45) Often common.
Pitcairn Islands Pitcairn Islands	Pitcairn Island	introduced	Fosberg, F. R./Paulay, Gustav/Spencer, T./Oliver, Royce (1989) (pp. 12-13) Vouchers cited: Paulay, Spencer & Schuster 667 (US), Paulay, Spencer & Schuster 673 (US)
Pitcairn Islands Pitcairn Islands	Pitcairn Island	introduced invasive	Florence, J./Chevillotte, H./Ollier, C./Meyer, J.-Y. (2011) "Certainement la graminée la plus commune dans toute l'île, du bord de mer jusque dans la lande à Dicranopteris qu'elle tend à envahir". Voucher cited: J. Florence 10781 (PAP)
Pitcairn Islands Pitcairn Islands	Pitcairn Island		Bishop Museum (Honolulu) (1991) (voucher ID: BISH 642955) Taxon name on voucher: Sorghum halepense (L.) Pers.
Pitcairn Islands Pitcairn Islands	Pitcairn Island		Bishop Museum (Honolulu) (1991) (voucher ID: BISH 642956) Taxon name on voucher: Sorghum halepense (L.) Pers.
Samoa Western Samoa Islands	Upolu Island		Bishop Museum (Honolulu) (1904) (voucher ID: BISH 126872) Taxon name on voucher: Sorghum halepense (L.) Pers.
Solomon Islands Solomon Islands	Solomon Islands	introduced cultivated	Hancock, I. R./Henderson, C. P. (1988) (p. 110)
Solomon Islands Solomon Islands	Solomon Islands	introduced invasive	Shine, C./Reaser, J. K./Gutierrez, A. T., eds. (2003) (p. 166) Moderate invader.
Tonga Ha‘apai Group	Lifuka Island	introduced invasive	Yuncker, T. G. (1959) (p. 66) There is some question as to whether or not the species in Western Polynesia is S. halepense. Whistler (1988) identifies it as S. sudanense (Piper) Stapf. Voucher cited: Yuncker 15722.
Tonga Ha‘apai Group	Lifuka and Foa Islands	introduced invasive	Space, James C./Flynn, Tim (2001) (p. 75)
Tonga Tongatapu Group	‘Eua Island	introduced invasive	Yuncker, T. G. (1959) (p. 66) There is some question as to whether or not the species in Western Polynesia is S. halepense. Whistler (1988) identifies it as S. sudanense (Piper) Stapf. Voucher cited: Yuncker 15476
Tonga Tongatapu Group	Tongatapu Island	introduced invasive	Yuncker, T. G. (1959) (p. 66) There is some question as to whether or not the species in Western Polynesia is S. halepense. Whistler (1988) identifies it as S. sudanense (Piper) Stapf. Vouchers cited: Hürlmann 33, Hürlmann 50, Yuncker 15163
Vanuatu New Hebrides Islands	Vanuatu (Republic of)		Swarbrick, John T. (1997) (p. 97)
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis (‘Uvea) Island	introduced	Meyer, Jean-Yves (2000) (p. 107) "Potential invader". Roadsides.
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis (‘Uvea) Island	introduced invasive	Meyer, Jean-Yves (2007) (p. 28)
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis and Futuna Islands		Swarbrick, John T. (1997) (p. 97) There is some question as to whether or not the species in Western Polynesia is S. halepense. Whistler (1988) identifies it as S. sudanense (Piper) Stapf.
Wallis and Futuna Wallis and Futuna (Horne) Islands	Wallis and Futuna Islands	introduced invasive	Comité français de l'Union Internationale pour la Conservation de la Nature en France (2010)

Pacific Rim
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
Australia Australia (continental)	Queensland	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 59-60)
Chile (continental) Chile	Chile (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 59-60)
China China	China (People's Republic of)		Hafliger, Ernst/Scholz, Hildemar (1980) (p. 136)
China China	Hong Kong	introduced invasive	Wu, Te-lin (2001) (p. 348) In valleys, by riverside on farmland.
Colombia Colombia	Colombia (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 59-60)
El Salvador El Salvador	El Salvador (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 346)
Guatemala Guatemala	Guatemala (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 346)
Honduras Honduras	Honduras (Republic of)		Holm, Leroy/Pancho, Juan V./Herberger, James P./Plucknett, Donald L. (1979) (p. 346)
Indonesia Indonesia	Indonesia (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 59)
Japan Japan	Japan (country)	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 192)
Mexico Mexico	Mexico (United Mexican States)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 60-61)
New Zealand New Zealand	New Zealand (country)	introduced invasive	Edgar, E./Connor, H. (2000) (p. 610) "Crops (especially maize), cultivated ground, waste ground, footpaths, railway lines. Aggressive and extremely difficult to eradicate because of the extensive, very strong rhizomes".
Nicaragua Nicaragua	Nicaragua (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 61)
Perú Perú	Perú (Republic of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (pp. 60-61)
Taiwan Taiwan	Taiwan Island		Hafliger, Ernst/Scholz, Hildemar (1980) (p. plate)
Thailand Thailand	Thailand (Kingdom of)	introduced invasive	Holm, Leroy G./Plucknett, D. L./Pancho, J. V./Herberger, J. P. (1977) (p. 61)

Indian Ocean
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
British Indian Ocean Territory Chagos Archipelago	Diego Garcia Island	introduced	Topp, J. M. W. (1988) (p. 18)
British Indian Ocean Territory Chagos Archipelago	Diego Garcia Island	introduced invasive	Whistler, W. Arthur (1996) (p. 25)
British Indian Ocean Territory Chagos Archipelago	Diego Garcia Island		National Tropical Botanical Garden (U.S.A. Hawaii. Kalaheo.) (1995) (voucher ID: PTBG 43835) Taxon name on voucher: Sorghum halepense

Comments:  A problem species in Hawai‘i. A Class A (eradicate) noxious weed in New Zealand. Old plants contain hydrocyanic acid and are dangerous to livestock.

Fosberg et al (1987; p. 60) list three varieties: S. halepensis var.halepense f. halepense, present on Saipan and Rota; S. halepense var. halepense f. muticum (Hack.) Hubb., present on Saipan, Tinian, Rota, Guam, Palau, Chuuk, and Pohnpei; and S. Halepense var. propinquum (Kunth) Ohwi, present on Saipan and Palau.

Control:  Additional control information from the Bugwood Wiki.

Prevention and dispersal: Prevention of seed dispersal and rhizome production is an important measure to avoid high Johnson grass infestation in crop areas. Seeds are normally dispersed through wind, water, animals and contaminated crop seeds, therefore slashing the plants at the beginning of the flowering stage in field margins, ditchbanks, canals and crop land and/or avoiding animal grazing in infested areas help to prevent new Johnson grass infestations.

Physical: Mechanical control of Johnson grass aims to prevent new rhizome production and must be implemented within the first month after shoot emergence. McWhorter (1989) considers that cultivation is most effective when the grass is about 36 cm tall. This helps prevent plants from forming rhizomes or seeds. In arable land Johnson grass infestations may be reduced by dragging the rhizomes onto the soil surface with a sweep or spike-tooth tiller during land preparation as this facilitates desiccation by sunlight (Crovetto and Rojo, 1957; Grupce, 1975; Labrada et al., 1982). Desiccation of rhizomes can be accelerated by cutting them into fragments less than 5 cm length. Rhizomes dried to 20% of their original weight completely lose their regenerative ability (Anderson et al., 1960). In fruit tree orchards regular mowing when the shoots are 20-25 cm tall tends to deplete rhizome food reserves and limits further rhizome production.

Pasturing over a period of several seasons is advocated as an effective method to reduce Johnson grass stands (Hauser and Arle, 1958; McWhorter, 1981). Miller et al. (1962)also indicated that geese provide excellent control of Johnson grass and other grasses in cotton, but required a high level of management.

Chemical: Johnson grass is not easily controlled with herbicides but several systemic foliarly-applied compounds can be effective. Glyphosate is useful in pre-planting treatment, applied to well-developed foliage 2-3 weeks before planting or seeding, and may also be used in fruit tree orchards. Post-emergence application of fluazifop-butyl, haloxyfop-methyl, fenoxaprop-ethyl, quizalofop-ethyl and sethoxydim are selective in broadleaf crops and provide control of seedlings and suppression of established plants. A single application of these herbicides is not usually enough to reduce heavy Johnson grass infestations below the economical threshold in the affected crops.

In sugar cane, post-emergence treatment with compounds such as asulam, dalapon and MSMA have been selective in the crop (Millhollon and Fanguy, 1989). These compounds are usually applied when the shoots are 20-25 cm high. Dalapon is less selective to sugar cane than asulam or MSMA, and application should be directly onto the weeds, avoiding any contact with cane foliage.

Trifluralin as a soil-incorporated pre-planting treatment is effective for the reduction of Johnson grass stand from rhizomes. This treatment is most effective against short rhizomes (less than 10 cm) (McWhorter, 1974). Good to excellent effectiveness is provided by a second treatment in the second year of a Johnson grass control program (McWhorter, 1989). This treatment is selective in crops such as sugar cane, beans, soybeans, groudnut and cotton (McWhorter, 1974; McWhorter, 1977; Millhollon, 1978; Kleifeldet al., 1986; Labrada et al., 1987). However, this treatment is not selective in all sugarcane varieties (La O et al., 1985). Another useful dinitroaniline herbicide for the control of Johnson grass seedlings is pendimethalin.

Pre-seeding soil-incorporated EPTC+dichlormid is also effective for Johnson grass control in maize crops (de Falcón et al., 1985).

It is important to stress that chemical control measures alone do not usually control Johnson grass. Furthermore, chemical treatments are not always economically feasible for smallholder farmers. Therefore, the best control option for this perennial weed is the integration of land preparation, crop rotation and rational chemical treatments.

Additional information:
Information on the Environment Bay of Plenty, New Zealand, web site.
Photos and additional information at University of Florida, Center for Aquatic and Invasive Plants.
Information from the Bugwood Wiki.
Information from the Global Invasive Species Database.
Species profile from the U.S. Department of Agriculture's National Invasive Species Information Center.

Additional online information about Sorghum halepense is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Sorghum halepense as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Sorghum halepense may be available from the Germplasm Resources Information Network (GRIN).

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