Pink Invasion of Tshwane

Pompom weed (Campuloclinium macrocephalum) is an ornamental South American herb belonging to the daisy family, Asteraceae. It is rapidly becoming the most serious threat to the conservation of grasslands in South Africa.

Infestations become conspicuous when the plants are in flower between December and March, transforming the veld from green to pink. The plant initially establishes itself in disturbed sites such as roadsides, but then invades natural grasslands, open savanna and wetlands.

Pompom weed is a perennial, erect herb up to 1.5 or even 2.0 m high. The stems are covered with rough, bristly hairs. Leaves are scattered along the length of the stem but clustered at the base to form a rosette. The plant has a short woody rootstock that ends in thick tuberlike perennial roots. In spring shoots arise from, and in autumn die back, to the rootstock. The showy pink flowerheads are produced in dense clusters at the ends of the aerial stems. The flowerheads are replaced by brown, fluffy seedheads. Pompom weed survives fires and frost during the winter months because all of its living components are in a dormant state underground. Under drought conditions during summer it can revert to a dormant state by withdrawing its nutrients from the shoots back to the roots. It has therefore evolved strategies to survive and multiply in grassland and savanna ecosystems in South Africa.

Legislation:

Pompom weed is a declared weed (category 1 plant) according to CARA. It is illegal to harbour, plant, propagate or sell pompom weed. Landowners are compelled to control pompom weed by whatever means is deemed appropriate.

Management and control:

Management should aim to maintain the natural vegetation in a healthy, productive state as this will help to limit pompom invasion. So far the only herbicide registered for use on pompom is Brush-Off by DuPont. Physical methods of control include uprooting and burning the plant. However this is only recommended where there are few plants as disturbance of the soil will only encourage further invasion of weeds.

It is not recommended to plough lands as this will damage the rootstock, stimulating further vegetative growth and denser stands.

Investigations into biological control using introduced insects and pests of pompom weed is in progress.

For further information on pompom weed and its control go to the ARC website (www.arc.agric.za) for publications by the Plant Protection Research Institute’s Weeds Division.

Information Courtesy of SAPIA News

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