Opuntia stricta (Haw.) Haw., Cactaceae

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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Risk assessment results:  Reject, score:20 (Go to the risk assessment)

Common name(s): [more details]

English: erect prickly-pear, southern spineless cactus

Habit:  cactus

Description:  "Spreading to erect shrub to 2 m. Basal stem-segments sometimes thickened, trunk-forming; upper segments elliptic to obovate, 10-35 cm long, 7-20 cm wide, glabrous, dull green to grey-green. Leaves conical, 4.5-6 mm long. Spines up to 11 per areole, 1-6 cm long, yellow to brown; glochids yellow. Flowers 5-6.5 cm diameter; petaloid lobes spreading, yellow. Fruit obovoid with depressed apex, 4-6 cm long, 2.5-4 cm diameter, purple. Seeds 4-5 mm long, pale brown" (George, 1984; p. 71).

Habitat/ecology:  Invades grass- and shrubland, rangeland, disturbed sites.  "In the native range, this cactus grows on coastal dunes, on shell mounds, and in coastal hammocks.  The plant spreads rapidly and forms extensive thorny thickets that impede wildlife and replace native vegetation"  (Weber, 2003; p. 291).

Propagation:  "Seeds are dispersed by birds and mammals, and remain viable for more than ten years.  Dislodged stem segments are carried by streams and root easily, forming new infestations"  (Weber, 2003; p. 291).

Native range:  "Tropical and subtropical coast of eastern North America, Bermuda, West Indies and adjacent South America" (George, 1984; p. 71).

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	Tassin, Jacques (2005)
New Caledonia New Caledonia Archipelago	Île Grande Terre	introduced invasive	MacKee, H. S. (1994) (p. 25) Vouchers cited: Guillaumin 8548, MacKee 24784, MacKee 34624 Spontané
Solomon Islands Solomon Islands	Solomon Islands		Swarbrick, John T. (1997) (p. 94)

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)	Australia (continental)	introduced	U.S. Dept. Agr., Agr. Res. Serv. (2013)
Australia Australia (continental)	Queensland	introduced invasive	Cronk, Q. C. B./Fuller, J. L. (2001) (p. 176)
China China	Hong Kong	introduced invasive cultivated	Wu, Te-lin (2001) (p. 75) Cultivated or naturalized.
Mexico Mexico	Mexico (United Mexican States)	native	U.S. Dept. Agr., Agr. Res. Serv. (2013)

Control: 

Physical:  "Smaller infestations may be removed manually."

Chemical:  "The best time for chemical control is before fruit swelling occurs, because seeds from unripe fruits are also viable.  A very effective control is applying MSMA by stem injection.  Frequent follow-up programmes are necessary to treat regrowth and seedlings"  (Weber, 2003; p. 291).

Biological: "The biological control of prickly pear, largely by the introduction of the Phycitid moth Cactoblastis cactorum Berg. from Argentina, is one of the most spectacular successes of economic entomology" (George, 1984; p. 71).

Opuntia stricta is also controlled by a cochineal insect, Dactylopius opuntiae.

There is detailed information about identification and control of opuntioid cacti--including Opuntia stricta--in Managing opuntioid cacti in Australia: Best practice control manual for Austrocylindropuntia, Cylindropuntia, and Opuntia species produced by the Western Australian Agriculture Authority.