Gorgeous, but dangerous
The main threat arises when the pompom weed takes over so much of the grass that herbivores eat that the animals eventually starve to death. This reduction in the numbers of herbivores threatens food security and farming.
Aliens are dangerous. This is the belief of many people around the world. In fact, the common belief that aliens will come to our planet and destroy nature and subsequently humans as well, has remained a part of western society for hundreds of years.
An alien is a foreign body, for which we don’t necessarily have an antidote, poison, or manner of destruction. They are fascinating, beautiful and scientifically important, but they strike fear into the hearts of people who know what the consequences of inaction are – an eventual takeover.
This is exactly the case with the alien weed called the Pompom or Campuloclinium macrocephalum.
The spectacular pink and purple flower grows in grasslands and true wetlands, decorating Gauteng’s plains and complementing the green grass.
But, its beauty comes with a significant threat – the plant has a major negative impact on plant biodiversity and grazing animals.
Firstly, it degrades grasslands by taking up too much space when it spreads. Secondly, herbivores such as cattle, find it distasteful, and will not eat it.
The main threat arises when the Pompom weed takes over so much of the grass that herbivores would normally eat that the animals eventually starve to death. The reduction in the number of herbivores threatens food security and farming.
In addition, the Pompom weed threatens the grasslands that herbivores in the game farming industry graze on, leaving them with a shortage of food as well. Because game farming is a major characteristic of the South African tourism industry, the lack of game will threaten the economy.
Scientists recently noticed that the number of Pompom weeds has increased significantly over the past five years, making the threat of this alien plant a substantial problem. The plant is so invasive that the Department of Nature Conservation has set out to destroy it entirely. They have also declared it a Category 1 weed, which means firstly that it is illegal to plant or cultivate it, and secondly that it must be controlled or eradicated where possible.
There are three ways to eradicate the plant:
Physical removal
This means the farmer or land owner must remove the weeds, their budding heads, and their roots to ensure they will no longer grow or sprout in the area. The uprooted weeds must be placed in a thick, dense bag and left in the sun to rot. Physical removal is only recommended for isolated plants as not removing the plants correctly can lead to stimulating the plants to produce more flowers and seeds.
Herbicides
If you do decide to use herbicides, do so early in the season, while the weeds aren’t flowering. The following herbicides have been proven effective, but don’t necessarily destroy all traces of the plant:
• Brush-Off (L4535) (metsulfuron methyl 600g/kg)
A granular powder. Apply with a back-pack sprayer to foliage of actively-growing plants early in summer.
• Forester (L8891) (formerly called Climax) (metsulfuron methyl 600g/kg)
A wettable powder. Apply to foliage.
• Access 240 (L4920) (picloram 240 g/L, a potassium salt)
A liquid. Apply to foliage from November to January.
Biological control
This means using insects to destroy the plants. The stem-deforming thrip (Liothrips tractabilis) has been proven to help destroy the plants. They damage the weeds by feeding on them. They were released during the summer of 2013–2014 in certain areas to determine how effective they would be over large areas, outside of a controlled environment. Although the insect is effective in destroying Pompom weeds, it will take a long time for it to spread sufficiently – and that could be too late.
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