Chrysanthemoides monilifera subsp. monilifera
Also known as
saltbush, bitou bush (subspecies rotundata), Higgins curse, Osteospermum monilifera
What does it look like?
Bushy, semi-woody, much branched shrub or small tree to 2-3 m with ribbed and woolly young stems that become smooth as they mature. Smooth, leathery, bright-green leaves (70 x 35 mm) have irregularly toothed edges and are arranged alternately on the stems. Bright yellow daisy-like flowers (25-30 mm diameter) are produced from September to February and are followed by hard oval green fruit (6-9 mm) which ripen to black and each contain a hard seed.
Why is it a problem?
Boneseed grows on sand dunes, scrubland, coastal cliffs, offshore islands and even rocky outcrops. It quickly forms an incredibly dense cover that shades out everything else and can limit access to coastal areas. A single boneseed bush can produce 50 000 seeds every year, and each seed can remain dormant for up to 10 years. Fast growing and maturing, and forms dense stands, excluding most other plants. Tolerates most coastal soil types, salt, fire, wind, poor soils, and drought. Rapidly replaces virtually all native species under 2 m and prevents the establishment of native plant seedlings. Colonises disturbed sites faster than native species, and creates heavy shade where high light levels should occur.
How does it spread?
Seeds are spread by birds, possums, by natural spread down cliffs below parent plants, in flotsam, occasionally soil disturbance, and possibly livestock. Common in coastal gardens in some areas.
How much of it do we have in our area?
Mangawhai Heads has a lot of boneseed. It invades all coastal areas, cliffs, sand dunes, estuary margins and roadsides.
What can we DO about it at Mangawhai Heads?
Mechanical clearance causing soil disturbance and bare ground after spraying both lead to increased seedling regrowth. Germinates freely after fire. Clear from adjacent coastal gardens to remove seed sources. Follow up 6-monthly. Encourage regeneration, densely replant cleared areas where necessary. Exclude livestock, prevent fire, maintain possum control and minimize soil disturbance.
Begin control at top of site, work along contours to prevent erosion and minimise reinfestation from above. Easiest during spring flowering when visible.
- Hand pull all but the largest plants (all year round) when not in seed. Leave on site to rot down.
- Stump swab (all year round): glyphosate (100ml/L) or metsulfuron-methyl 600g/kg (1g/L) or picloram gel or triclopyr 600 EC (100ml/L).
- Spray: glyphosate (10ml/L + penetrant).
Plants with seed must be buried deeply, burnt, or disposed of at a refuse transfer station. Follow up at six-monthly intervals to complete eradication.