What does it look like?
Montbretia is a stiff, leafy, clump-forming, evergreen or summergreen perennial with underground rhizomes. Flattened, light brown corms (35 x 15 mm) have a fibrous cover and form 3+ clusters at the stem base. Firm, sword-shaped leaves (90 x 2 cm) all rise from the base, and are erect to curving above, with a conspicuous mid-vein. Flowerheads are tall and zig-zag shaped. Solitary orange to crimson 6-petalled flowers (3 cm) are produced from January to February and develop into 3-sided seed capsules (5 mm long) that are reddish-brown and flat to triangular.
Why is it a problem?
Montbretia spreads through soil movement (such as from road graders and fill), vegetation dumping, and water flow, allowing it to expand from roadsides, slips, wastelands, and exotic plantations. It competes with groundcovers and small shrubs, hindering the establishment of native seedlings. Specialised low-growing species, particularly those in riparian margins, may be displaced. Montbretia is likely to invade a wide range of low-growing habitats, including open shrubland, disturbed or open forests, streamsides, alluvial river systems, fernlands, short tussock grasslands, and wetlands.
Control methods
Physical control
Dig out very small infestations, but this is usually ineffective for larger areas since corms tend to resprout. Dispose of removed corms by taking them to a refuse transfer station, burning, or deep burial.
Herbicide control
- Spray (full leaf stage) with glyphosate (10ml/L) + metsulfuron-methyl 600g/kg (4g/10L) + penetrant.
- Start at the upstream end of an infestation. Follow up 6-monthly. Montbretia thrives on disturbance as corms and rhizomes readily resprout. It resists fire. Sites regenerating to a canopy of over 2 m can normally be left alone. Replant with dense groundcover where appropriate.
- CAUTION: When using any herbicide or pesticide, PLEASE READ THE LABEL THOROUGHLY to ensure that all instructions and safety requirements are followed.
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