Written by author Clive Bromilow
The environmental issues of this world are growing and becoming more and more serious, as it poses a threat to our very survival on this planet. Alien and ‘invasive’ weeds are just one of these issues. In this series of blogs by author Clive Bromilow, of which this is the first, a lot of these species will be covered in order to bring attention to the problem plants in your environment and highlight what you can do to counter the spread of these invasive plants.
Alien and invasive weeds
Alien and invasive weeds compete with indigenous species, and they disrupt the lives of animals and insects that depend on these indigenous plants. Also, they don’t have ‘natural’ enemies, so they can flourish and increasingly cause problems in our environment! Some weeds, which have been here for decades, are no longer considered ‘invasive’ but are still problematic. Ones that have arrived in more recent times are invasive, which means they are growing, spreading and interrupting our natural environment. So, awareness of these weeds, what they do and what we need to do to stop them are very important things.
Bugweed (Solanum mauritianum)
If you look around, almost everywhere you will see growing patches of Bugweed, which is a well-known (and one of the worst!) alien weeds we have in South Africa. Bugweed has been in South Africa for over a hundred years (i.e. not invasive) and has become a huge problem in most of eastern South Africa, but especially in KwaZulu-Natal, where it can be seen totally swamping open land, forestry and even sugarcane plantations. The the fruits are also poisonous and act as secondary hosts for problem insects such as fruit fly – also big potential problems.
The National Environmental Management Act
The Department of Environmental Affairs (DEA) has published Regulations on Alien and Invasive Species (AIS) in terms of the NEMBA act, that categorises four different sections of alien weeds and the different ways of managing them to prevent further harm to the environments that they have invaded.
- NEMBA 1a are seriously ‘invasive’ species which arrived here in the last 60 years or so and must be controlled or eradicated wherever possible to stop them getting worse.
- NEMBA 1b are serious weeds but are not considered ‘invasive’ any more as they are well established. They must be controlled wherever possible and any form of planting or trading is strictly prohibited.
- NEMBA 2 are commercially grown plants but are also big weeds. Permits are required to grow these commercially. They are still considered a 1b if they occur out of these permitted areas and must be controlled.
- NEMBA 3 are mostly ornamental plants but are potentially invasive and can be very problematic. They can remain in the garden but must not escape. No further planting is permitted.
Bugweed is categorised as a NEMBA 1b plant, which means that it should be controlled or removed wherever possible.
What can we do about Bugweed?
A lot of open lands infested with bugweed are public areas and the control of these weeds is usually the responsibility of the relevant Municipality. Nature Conservations will be actively eroding this weed, but very little is being done in public areas. So, raising awareness of the problems, supporting conservations and pushing municipalities (wherever possible!) is what we can all try to do to help control this weed.
There are a couple of bio-control agents that have been introduced for Bugweed, but their effects are very limited. Bugweed can actually be killed quite easily by suitable herbicides, but there are always costs involved.
So, we must remove these plants wherever we can. Cut them down, paint the stumps with a suitable herbicide and remove all the seedlings that start to grow underneath them. We must also push others to do their job and this includes putting pressure on the Municipalities and all relevant land owners.
Remember, awareness of problem plants and spreading the news about their environmental impact and control measures is just one thing that needs doing to extend our survival on this planet!
Read more about Bugweed and other problematic plants around Southern Africa in Clive Bromilow’s book: Problem Plants and Alien Weeds of Southern Africa/Probleem Plante en Indringeronkruide van Suider Afrika.
