Senecio madagascariensis Poir., Asteraceae

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Present on Pacific Islands?  no

Primarily a threat at high elevations?  no

Risk assessment results: 

Reject, score: 15 (Go to the risk assessment (Australia))
High risk, score: 23 (Go to the risk assessment (Pacific))

Common name(s): [more details]

English: Madagascar fireweed, Madagascar ragwort, fireweed, variable groundsel

Habit:  herb

Description:  "An erect hairless annual or short-lived perennial herb 10 to 70 cm high, reproducing from the crown and by seed.  Stems erect, slender, 1 to many arising from the crown, 10 to 70, usually 10 to 50 cm high, branching above.  Leaves bright green; alternate, of variable size and shape, often narrow and rather fleshy, 2 to 8, usually 2 to 6 cm long, the broader leaf bases generally clasped around the stem; margins serrate, entire or lobed.  Flowers bright yellow, consisting of 13 ligulate ray florets, oblong to obovate, 10 mm long, and numerous tubular disc florets grouped into heads 15 to 20 mm diameter, each subtended by an involucre of 20 or 21 bracts; heads arranged in clusters at the ends of branches.  Seeds brownish, cylindrical, 1.5 to 3 mm long; covered with lines of short white hairs and crowned by a pappus of silky hairs. Root:  A shallow branching annual or perennial taproot with numerous fibrous laterals all within the upper 20 cm of soil"  (Parsons and Cuthbertson, 1992; pp. 304-305).

Habitat/ecology:  Subhumid to humid subtropical woodland on a wide range of soils (Parsons and Cuthbertson, 1992; pp. 304-305).

Propagation:  Seed, spread by wind, birds, animals and man (as a contaminant in hay and grain or on machinery). Spreads locally by rooting from nodes.

Native range:  South Africa.

Presence:

Pacific
Country/Terr./St. & Island group	Location	Cited status & Cited as invasive & Cited as cultivated & Cited as aboriginal introduction?	Reference & Comments
State of Hawaii Hawaiian Islands	Hawai‘i (Big) Island	introduced invasive	Lorence, David H./Flynn, Timothy W./Wagner, Warren L. (1995) (p. 24) Vouchers cited: S. Perlman et al. 10312 (PTBG, US), T. Flynn & D. Lorence 3080 (PTBG), W. Shishido s.n. (BISH)
State of Hawaii Hawaiian Islands	Kaho‘olawe Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2006) (p. 33) Vouchers cited: Starr, Starr & Tokishi 040330-3 (BISH), Starr, Starr & Higashino 040511-1 (BISH)
State of Hawaii Hawaiian Islands	Kaua‘i Island	introduced invasive	Lorence, David H./Flynn, Timothy W./Wagner, Warren L. (1995) (p. 24) Vouchers cited: L. Hume 497 (BISH, PTBG, US), W. L. Wagner & T. Flynn 6321 (BISH, US)
State of Hawaii Hawaiian Islands	Lāna‘i Island	introduced invasive	Starr, Forest/Starr, Kim/Loope, Lloyd L. (2006) (p. 33) Voucher cited: Starr, Starr, Anderson & Anderson 050623-2 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Martz, Kim/Loope, Lloyd L. (1999) (p. 11) East Maui. Voucher cited: Starr & Martz 980215-71 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Oppenheimer, Hank L./Bartlett, Randal T. (2002) (p. 4) West Maui. Voucher cited: Oppenheimer H30004 (BISH)
State of Hawaii Hawaiian Islands	Maui Island	introduced invasive	Starr, Forest/Starr, Kim (2012) (p. 88) East Mau. Voucher cited: Starr 110412-1 (BISH)
State of Hawaii Hawaiian Islands	Moloka‘i Island	introduced invasive	Oppenheimer, Hank (2013) (p. 18) Voucher cited: Oppenheimer, Perlman & Coelho H41209 (BISH, PTBG)
State of Hawaii Hawaiian Islands	O‘ahu Island	introduced invasive	Herbst, Derral R./Staples, George W./Imada, Clyde T. (2004) (p. 4) Vouchers cited: D. Arakaki s.n. (BISH 668939), K. Kawelo s.n. (BISH 695026), K. Kawelo s.n. (BISH 695028)

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)	New South Wales	introduced invasive	Motooka, Philip/Castro, Luisa/Nelson, Duane/Nagai, Guy/Ching, Lincoln (2003) "A serious pasture problem".
Australia Australia (continental)	Queensland	introduced invasive	Motooka, Philip/Castro, Luisa/Nelson, Duane/Nagai, Guy/Ching, Lincoln (2003) "A serious pasture problem".
Japan Japan	Japan	introduced	Mito, Toshikazu/Uesugi, Tetsuro (2004) (p. 190)

Comments:  On the State of Hawai‘i noxious weed list.  Toxic to livestock.

Control: 

Physical:  "Resting pastures is reported by rancher Polo Von Holt to control ragwort in his pastures in Kohala.  Ragwort can be controlled by grazing by sheep and goats, but too high a diet of fireweed will cause illness or death of these animals"  (Motooka et al., 2003).

Chemical:  "Very susceptible to 2,4-D, dicamba, MCPA, metsulfuron, and triclopyr when young and succulent.  Susceptible to glyphosate, although only application with wipe-on applicators to taller ragwort is possible to avoid injury to pasture species.  Mature ragwort susceptible to MCPA at 2 lb/acre, clopyralid at 0.5 lb/acre.  Tebuthiuron at 2 lb/acre effective.  Follow-up sowing of forage seed is recommended to reclaim the site and compete with regenerating ragwort.  Continuing monitoring is needed to control newly emerging seedlings before seed set"  (Motooka et al., 2003).

Biological:  "In 1999 various isolates of the fungal pathogen Puccinia lagenophorae were tested in quarantine as potential biological control agents against Senecio madagascariensis (fireweed). The rust infected fireweed, but also affected other Asteraceae, including species native to Hawaii. The Hawaii Department of Agriculture has reared potential insect biological control agents from Africa in quarantine: arctiid moths Secusio extensa and Nyctemera apicalis, and a tephritid fly Sphenella austrina. A Madagascar moth--Secusio extensa--appears to be highly specific and a voracious feeder of fireweed. Research continues on culturing this moth in anticipation of its release"  (Biological control in Hawai‘i).