WEED of the MONTH
Blackberry
BLACKBERRY ... or BLACKBERRIES
Most people are familiar with the Blackberry,
probably for two reasons: the sweet, juicy fruit
produced in autumn and the ferocious thorns on
the long canes. But Blackberry is not just one
plant - under the name Rubus fruticosus spp. agg.
(species aggregate) are grouped at least eight
closely related species of bramble that have gone
wild in NSW - and in all other states. Settlers from
Europe introduced their blackberries into many
countries in the last century - and they have
become major weeds in most of them. Truly a
plant out of place.
BERRY WELL KNOWN
The species known to us as Blackberry differ from each other in only minor details. Blackberries are perennial woody shrubs which produce long arching canes which may grow to 6 metres, and which are covered with numerous tenacious thorns. The leaves are hairy, and divided into three or five serrated leaflets. There are small prickles on the main veins on the underside and a prickly stem. Dark green on the upper surface, they may be almost white underneath because of the presence of fine hairs.
The five-petalled white to pink flowers,
produced from November to March, are followed
by succulent bunches of berries which ripen
from green to purplish black in late summer and
autumn. Each year new canes are produced and
some of the old canes die, but these dead canes
remain prickly and part of the thicket, which
becomes virtually impenetrable and may
eventually extend to hundreds of square metres
in area.
BERRY SUCCESSFUL
Like all successful weeds, Blackberry is not really too fussy about where it grows. Although it prefers fertile soils with good rainfall in cooler districts, Blackberry will tolerate drier conditions and quite a variety of soil types, although not dense shade. It is found in wet gullies and along creek banks, in open areas and wasteland, along roadsides and embankments, on farmland and in gardens, on forest margins and in clearings, along stormwater channels and in swamps - wherever vegetative cover has been disturbed, ideal conditions for Blackberry have been created.
Below a drainage easement, Katoomba
Foxes and birds play a major part in the distribution of its seed, but Blackberry does not just depend on seed to reproduce - it has some special mechanisms of vegetative growth which allow its rapid spread and make it difficult to eradicate. First year canes do not bear fruit, but in autumn they root down and produce another plant where their tips touch the ground; this separates from the parent plant when the cane dies. In response to slashing or burning, Blackberry will shoot vigorously from its crown, which is the cane-producing woody rhizome in the centre of the plant. Blackberry can sucker , and it can also grow from root fragments.
BERRIED IN THE BUSH?
Blackberry does not often invade intact bushland. It establishes most readily on disturbed and neglected sites, and in areas affected by urban stormwater runoff.
It is a highly invasive plant, competing aggressively for soil moisture and nutrients, quickly covering large areas with a dense canopy, excluding light from the soil surface and replacing native vegetation, threatening sensitive and fragile ecosystems such as creeks, swamps and tall open forests. Blackberry quickly becomes a monoculture, completely dominating the site, and affecting wildlife habitats.
The impenetrable nature of the thickets formed by Blackberry restricts access of wildlife to streams, and provides excellent cover for snakes, rabbits and foxes. Access for control is made difficult and painful by its thorny nature, and its dense stands are a considerable fire hazard.
Here Blackberry has climbed
3m into shrubs in a
swamp in Wentworth Falls
BERRY PERSISTENT PLANTS
Because Blackberry exhibits so many different survival and reproductive methods, it is a difficult plant to eradicate. Digging it out is effective - but only if you can get rid of all the roots, and some of these have been known to go a metre deep. Root fragments left behind can shoot, and seed in the soil will appreciate the light, warmth and disturbance - and germinate.
Chemical control using herbicide can be effective. Small infestations can be treated by the stem-scraping method or the cut and paint technique. If you have a large area of Blackberry it may need to be sprayed. The best time to spray is after petalfall and before fruit set: ie, late summer to early autumn, completely covering all canes, leaves and suckers, which should not be cut for several months. Another approach is to cut back the canes, then spray the regrowth in late spring. Follow-up will still be needed to deal with regrowth and seedlings.
Biological control with Blackberry Rust Fungus continues to
be investigated both in Australia and overseas. The many
species and hybrids of Blackberry show different susceptibility to
the various strains of the rust. As with most biocontrols, the best
that can be hoped for is a reduction in vigour rather than
complete eradication. The rust has no harmful effect on the
environment or on other plants or animals, and it is not
allergenic.
BERRY SIMILAR PLANTS
Just to make life difficult, there are three native Rubus species found in the Blue Mountains. None is as robust or aggressive as the Blackberry, nor do they form extensive thickets. All are found in sheltered, moist areas and rainforest, rather than in open disturbed sites. Rubus parvifolius, the Native Raspberry, is a small scrambler with white felty undersides to its deeply wrinkled leaves, and rose-like pink flowers in spring. Rubus rosifolius, the Rose-leaf Bramble, is a weak shrub with larger thin, soft leaves which are green on both sides. Rubus hillii, the Broadleaf Bramble, is a strong scrambler, and the only one not to have compound leaves, although they are deeply lobed, with thick rusty hairs beneath. The small summer flower is pale pink. All bear an edible red fruit that resembles a raspberry.
BMCC BLACKBERRY SPRAYING PROGRAM
Our Council is obliged by law to fully and continuously suppress and destroy this plant. The spraying of Blackberries on public land begins in October. Council’s policy is to:
- program the spraying in locations adjacent to recreation areas before fruiting;
- use a dye in the herbicide;
- issue a media release in the Gazette, alerting the public to Council practices and the health hazards of eating treated berries.
As you know, there are many Blackberry infestations in the Mountains, and they
cannot all be treated at once.
To be safe, never eat blackberries picked in the Mountains.
YOUR LEGAL RESPONSIBILITIES
Blackberries are classified as W2 noxious weeds, and you are responsible for eradicating this plant on your property or one that you occupy. Blackberries must be fully and continuously suppressed and destroyed. The law imposes serious penalties for those who fail to comply with it. For advice on how to manage your blackberry problem ring BMCC on 4780 5000, and ask to speak to the Noxious Weeds Section.
BARON BOTANIST BACKS BAD BERRY
There is some evidence that plantings of Blackberry were made at Bathurst in the 1830s, and the plant was certainly in Australian gardens, nursery catalogues and the Melbourne Botanic Gardens by 1850. But the heavy promotion of Blackberry occurred in the 1860s, by members of ‘acclimatization’ societies and by the Victorian Government Botanist, Baron Ferdinand von Mueller, one of Australia’s great plant collectors and botanists. Blackberry, it was claimed, not only provided edible fruit, but also controlled erosion along streams and was ideal as a hedge plant.
Megalong Valley
Alas for those areas which followed such advice! Blackberry was recognised as a serious weed less than 20 years later, when it was claimed to be ruining farmland in NSW, and when it was proclaimed noxious in part of Victoria. The Baron, however, remained recalcitrant, writing in 1895 that Blackberry “deserves to be naturalised on the rivulets of any ranges”. Blackberry is now one of Australia's Weeds of National Significance, and unquestionably one of the worst weeds in the country.
More information on Blackberry and how to control it.
