The Agricultural Research Council (ARC) said this member of the daisy family is quickly becoming an increasing threat to grassland conservation in South Its spread has especially boomed over the past 10 years. Arne Witt, manager of the weeds division of the ARC at the Plant Protection Research Institute (PPRI) said the pompom usually starts growing in disturbed sites like roadsides. It then invades natural grasslands, open savannah and wetlands. “This weed displaces native species, reducing both the biological diversity and carrying capacity of wetlands and veld.” Witt said he believed vehicles are spreading the weed, as it is usually first found next to the road. Pompom also needs water to spread.
Though the plant is not toxic to cattle, it could have serious implications for crops and grazing. The best way to control pompom is to spray it with herbicide, said Witt. Du Pont’s Brush-Off is the only product registered to destroy the weed, but others are being tested. Chemicals are 80% effective and farmers should apply them annually to keep pompom at bay. If farmers spray during the flowering stage, they should first remove the flower, said Witt. “Each flower can disperse about 150 seeds through wind.” He added that uprooting the plants and other physical methods are ineffective and worsen the problem through disturbance. “It is not advisable to plough lands with pompom weed as this will damage the rootstock, stimulating further vegetative growth and denser stands.” The is currently researching biological controlling methods. These include the introduction of insects and pests of pompom weed. It is uncertain how or when pompom was first introduced to South Africa.
The the earliest record noted in the Pretoria National Herbarium is of a specimen collected in Johannesburg in 1962. The provinces currently most affected by the plant are Gauteng, Mpumalanga, Limpopo, North West, KwaZulu-Natal, Eastern Cape and Free State. The areas in the Mpumalanga Lowveld where pompom is found are around Nelspruit, White River and Barberton. Other invaded areas are around Polokwane, Haenertsburg, Woodbush, Duiwelskloof, Tzaneen, Piet Retief, Badplaas, Graskop, Kroonstad and George in the Cape. Witt is especially concerned about the spread of pompom into nature reserves. The Lekgalameetse Nature Reserve near Tzaneen and the Welgevonden Game in the Waterberg are both currently under threat. – Susan Botes
