Boneseed
Boneseed Chrysanthemoides monilifera ssp. Monilifera is a native of South Africa and was first brought to New Zealand as an ornamental plant, but it's now banned from sale, distribution and propagation because of its invasive nature.
Close up of a boneseed flower
Why boneseed is a problem
Boneseed - a daisy - is a garden escapee that jumps the fence by means of wind, water, birds, or garden dumping. As its other name 'salt bush' implies, it is a salt tolerant, fast-growing, and prolifically seeding shrub.
Boneseed grows on sand dunes, scrubland, coastal cliffs, offshore islands and even rocky outcrops. There is an ever-present threat from boneseed at Maunganui Bluff, where you can visit showy native Hebe speciosa growing on these cliffs. Boneseed plants in adjacent dunes and roadside areas can spread quickly to form incredibly dense cover that shades out everything else and can limit access to coastal areas. A single boneseed bush produces 50,000 seeds every year, and each seed can remain dormant for up to 10 years.
How you can identify boneseed
Boneseed grows up to 3 metres tall and has leathery leaves with toothed edges. The name boneseed comes from its bone-coloured hard seeds, but the most distinctive thing about it is the bright yellow daisy-like flowers.
Boneseed
Control of boneseed
A biocontrol, leaf rolling caterpillar has been brought in from South Africa and released in Northland at Hihi, Ahipara and Mangawhai to help stop the spread of boneseed in New Zealand. Caterpillars feed on shoot tips and with silken thread web several leaves together to make shelters - a sure sign of the presence of the biocontrol agent.
Small plants can be hand pulled and larger plants cut at ground level. You should paint stumps immediately with herbicide to prevent re-growth, and you must make follow-up visits for regular seedling removal.
You can compost or mulch plants without seeds, but you should bury plants with seed deeply or take them to a refuse transfer station. For more control options, check out www.weedbusters.org.nz
How you can help stop the spread of boneseed
Individual action is very powerful and in Ngunguru's beach community in Northland, a single Weedbuster resident has gone around and killed all the boneseed. This is achievable in your area too.
Consider trying some yellow-flowered natives instead, for example, Brachyglottis greyii - a spreading shrub with silver edged grey leaves, or Korokio (Corokia species) - hardy shrubs and great for coastal areas, or go with purple instead and get a gorgeous Hebe speciosa.
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