In a previous blog we spoke about the beauty of the wildflowers of Ezemvelo Nature Reserve and how some of them blossom at the same time, creating a colourful ground cover.
However, hiding between these beautiful and colourful flowers, one intruder is taking over the grasslands of South Africa. I name it the ‘evil beauty’ – the pompom weed or Campuloclinium macrocephalum is an alien or invasive plant as it is not native to South Africa but from South America.
It was introduced on the continent as an ornamental flower in people’s gardens and, due to the absence of natural enemies, the weed started to invade the land, outcompeting indigenous species. Pompom weeds then rapidly became the most serious threat to the conservation of the grasslands of South Africa, according to the Agricultural Research Council.
Ezemvelo Nature Reserve, being mostly grassland habitat, is no exception and has to deal with this invasive plant.
This pretty pink and purple flower is a perennial plant that grows 1.5m high. Because it retreats underground during winter, the weed survives fires and frost. Pompom also produces a lot of seeds that are easily dispersed by flower-pickers and wind.
Besides proliferating rapidly, this invasive plant also seriously degrades the veld as its roots produce enzymes that stops natural grasses from growing properly. Aerial parts are also suspected to inhibit the growth of other plants around.
To control and limit the invasion of pompom weed, different control methods can be used, and for a better treatment they can also be combined. Herbicides can be sprayed on stems and leaves, stems can be repeatedly cut back to weaken the weed, the plant can be dug up, or a biological control agent (natural insect enemy) can be introduced. The last method must be highly controlled, as we do not want the insect to kill indigenous plants.
A good method, and the one we use on our reserve, is a combination of spraying herbicide onto the leaves, as well as cutting the stems and flowers that are later burnt.
If you see the pompom weed on roadsides, please do not pick it up even if it looks pretty, so you don’t help its invasion through the country.