Pompom weed is an invasive weed of grasslands, savanna and wetlands that threatens conservation and agriculture in South Africa. This weed is listed as a category one plant under the Conservation of Agricultural Resources Act (Act No 43 of 1983). Plants from this category are prohibited on any land or water surface in South Africa and must be controlled or eradicated where possible. Pompom weed is drought tolerant and possibly allelopathic ie it might have a chemical defense mechanism that inhibits the growth of other species.
Pompom weed retreats underground during winter and people tend to forget about it. It is rapidly displacing native species, reducing both the biological diversity and carrying capacity of wetlands and veld. Infestations become conspicuous when the plants are in flower, usually between November and April, transforming the landscape from green to pink. The plant initially establishes itself in disturbed sites, such as roadsides, overgrazed areas and then invades grasslands, open savanna and wetlands.
Pompom is expanding at such a rate that chemical control will soon become unpractical and unaffordable. Biological control is the only sustainable control option against pompom weed. The pompom weed webpage is fully functional and can be accessed at the ARC homepage www.arc.agric.za. This website provides assistance in distinguishing pompom weed from similar-looking indigenous and alien plants, information on chemical control, progress with biological control, contacts in the national department of agriculture for law enforcement, research projects and current distribution of the weed.
Currently, this weed is most prominent in Gauteng, but is expanding its distribution into Limpopo, Mpumalanga, North-west Province, KwaZulu-Natal, Eastern Cape and the Free State. The map included shows all the known localities of pompom weed in the SAPIA database until the end of February 2008. New SAPIA records for 2007/2008 are shaded in blue.
In Mpumalanga, pompom weed (Campuloclinium macrocephalum) is expanding its range around White River, Nelspruit and Barberton; the largest infestations occurring in the Barberton/ Nelshoogte/ Badplaas area. Isolated plants have been recorded near Sabie, Graskop, Lochiel, The Brook and Chrissiesmeer—these should be primary targets for control. Should you have Pompom weed in your locality which is not yet recorded, please contact the Invasive Species Control Unit/ Working for Water on 012 426 5214 or Lesley Henderson (ARC- Plant Protection Research Institute) on 012 843 5035 for further investigation and clearing assistance.
By Nacy Matloko