Family: Rosaceae (roses, briars, brambles)

Status: Weed of National Significance (one of Australia’s top 20 weeds). Declared noxious in category W3 in Bega Valley and Eurobodalla LGA’s (landholders must prevent spread and reduce infestations to the satisfaction of the Local Control Authority), and in category W2 in Shoalhaven and Illawarra (must be continuously suppressed and destroyed).

Description:
Deciduous spreading shrub 1 to 2m high, with large triangular backward-pointing thorns on stems and leaves. Compound leaves with 3 or 5 wrinkled leaflets, which have a white underside. Flowers are large (2-3cm) and white petalled. Blackberry fruits are large and succulent, ripening to purple-black.

Preferred habitat and impacts:
Blackberry does best in cool moist sites (creek banks, south-facing slopes, gullies), with plenty of sun penetration, but will grow almost anywhere, except in dense shade.
Thickets can choke out all other vegetation and the thorny canes impede access. They provide rabbit harbour. Sheep can become trapped by the thorns and die. Blackberry is often ignored on creek banks in the mistaken belief that it is "holding the banks together". However, because the ground is generally bare under the blackberry, it does little to prevent erosion. A varied cover of native shrubs, grasses and sedges would be much more effective.

Dispersal:
Birds and foxes. Blackberry also spreads vegetatively by rooting from the branch tips where these touch the ground. It will also sucker from the crown and the roots if the parent plant is cut down.

Look-alikes:
There are a number of species of exotic blackberry within the Rubus fruticosus aggregate, all with slightly different leaflets, but most are very similar.
There are several species of "native raspberry" which could be mistaken for blackberry. The most common, small-leaved bramble, (Rubus parvifolius) is a smaller trailing plant with smaller pink flowers and tasty but very small bright red fruits. Native raspberry (Rubus rosifolius) is upright in habit, with narrow leaflets, large white flowers and large red berries, which are disappointingly dry and gritty. Molucca bramble (Rubus moluccanus var trilobus, formerly R. hillii) is a large shrub or climber with leaves which are three-lobed but not compound, and densely covered with buff coloured hairs on the underside. Flowers are pale pink or white and fruits red. Bush lawyer (Rubus nebulosus) is a rainforest climber occurring from about Batemans Bay north. It has large thorns and the five leaflets up to 10cm long are on long stalks, making the whole leaf very large.

Control:
Spraying with a woody weed specific herbicide is the simplest method of blackberry control. Goats provide very good control in suitable situations. However, they need good fencing, can cause further erosion in the steep gully situations where blackberry often occurs, and are also rough on native vegetation. Slashing can keep blackberry from forming tall clumps, in situations where tractor access is not a problem. However, it never really gets rid of the plant. Small blackberry plants can be dug out, but will re-sprout if any roots are left behind. An introduced fungus, blackberry rust, was released in the 1980’s, and occurs in the region. It can become common in wet summers, reducing the vigour of plants and possibly preventing fruiting. The rusty coloured spore clusters can be seen on the underside of the leaves when it is active.