Lower Mpushini Eco Focus
Focussing on Wildlife Conservation, Area Rehabilitation, and Lifestyle Education in the Lower Mpushini Valley Conservancy
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From the Editor
Alien invader plants are a real problem in South Africa and in our area in particular. Most properties have at least some of the aliens growing on them. Of particular concern are Lantana, Chromolaena, Bugweed, Balloon Vine, Syringa and some other introduced exotics that have escaped from our gardens. Remember, all introduced plants that are not indigenous to our area have the potential to become invaders due to the fact that their natural controllers may not exist in our area. Our article “Alien plant invaders and their control” takes up most of the space in this issue.
A leaflet on our open gardens and trails weekend on 17 and 18 March is attached to this issue. Please make an earnest attempt to support this event and to offer your services. Contact Darlene Bond or Pandora Long if you would like to help.
Tel: Darlene: 082 9335036 Pandora: 072 6928124 or 033 3261777
Neville Durow
Nature’s Hideaway
Cell: +27827084285
E-Mail: neville.durow@vodamail.co.za
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In this edition:
In this edition:
Armed poachers are active!
Alien plant invaders and their control
Community Focus
Conservancy holds well attended meeting
Garth Carpenter hosts another “Campfire Tales” evening
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Armed poachers are active!
On Tuesday, 20 February I received a call from Danny Ferreira to inform me that he had just heard a rifle shot that sounded as though it came from his neighbour, Leon Robberts’, property. I immediately armed myself and left the house to get my bakkie started. While on the way up my driveway I heard a second shot. This was confirmed a few seconds later when Danny again phoned me. I drove onto Leon’s property and saw a number of Impala grazing on the lawn at his factory building. They appeared to be calm so that I could deduce that they hadn’t been shot at. I then drove down to his dam and shone the vehicles lights across the dam onto the hillside but saw nothing.
I then drove to Danny’s and we kept a lookout for lights and noises of trespassers. After more than an hour we gave up our vigil.
It would appear that the poachers had entered the valley on foot from near the Lion Park and made their way out of the valley in the same way. I presume that they carried their prey out with them.
Please keep vigilant and let me know immediately you hear or see any poaching activity in our area.
Alien plant invaders and their control
(Information obtained from E-KZN Wildlife’s website)
Alien plants are widespread in KwaZulu-Natal, both in cultivated areas and the wild. The majority do not pose a threat but a few, by virtue of their aggressive qualities, have the capacity to invade natural habitats and overwhelm some, or even all of the indigenous vegetation. Alien plants usually have much greater potential for invasion than indigenous plants because they have not had time to settle into equilibrium in their new community. They may find growing conditions superior to those under which they evolved in their native land or there may be less pressure from herbivores or competitors. Many properties within the area of the Lower Mpushini Valley Conservancy have become heavily invaded by alien plants, particularly Lantana, Chromolaena, Balloon Vine and Syringa.
These invaders come in many shapes and sizes. They may be trees, shrubs, small herbaceous plants, creeper vines or waterweeds but they all have the ability to spread and reproduce rapidly and to resist all but the most determined control attempts. Alien invaders thus constitute one of the greatest single threats to conservation in KwaZulu-Natal.
Some of the invaders arrived by accident but the majority of introductions were deliberate, for reasons, which appeared valid at the time. Part of the problem is that there is no set formula for recognizing potential invaders. Recognition occurs after encroachment has started. The foci of many infestations have been intentional plantings in gardens and ponds and more than half of KwaZulu-Natal’s problem invaders were introduced as ornamentals, either as garden plants, or as container plants, or as plants in aquaria. Some of these species are still being sold by nurseries and planted, despite legislation to the contrary. It is everyone’s duty to spread awareness of the dangers posed by invasive plants.
The important invaders
Chromolaena (Chromolaena odorata) is a spindly shrub native to South America. It is firmly established at the coast and in the warmer parts of KwaZulu Natal. It is a serious problem in our conservancy. Chromolaena invades disturbed ground and road edges where dense stands form and spread rapidly, excluding all other vegetation.
Lantana (Lantana camara) is a prickly plant that is native to America. It is widespread in KwaZulu-Natal excepting the cold areas. Lantana invades forests edges and bushveld thicket and can smother large trees. It is poisonous and fatalities to children and cattle have occurred.
American bramble (Rubus cuneifolius) is a prickly scrambler, which appears to be a hybrid between an introduced, and a local species. It is widespread in the mist belt and highland areas where it invades open veld and forest. It forms dense stands, which prevents any form of land use.
Sesbania (Sesbania punicea) is a shrub from South America that is now spreading rapidly through KwaZulu-Natal where it thrives on riverbanks and on waste ground. Sesbania forms dense stands, excluding natural vegetation. The seeds are poisonous to both domestic animals and wildlife.
Syringa (Melia azedarach) comes from tropical Asia. It is fast growing and, with the assistance of fruit eating birds, spreads rapidly into almost any habitat. It can dominate a woody community particularly alongside rivers. It is particularly evident along the Mpushini River.
Bugweed (Solanum mauritianum) is a weedy tree native to tropical Asia. It is widespread in KwaZulu-Natal particularly in wetter parts of the Midlands where it colonises disturbed ground. In doing so it prevents natural veld regeneration. Bugweed also harbours the fruit fly, which is an important orchard pest.
Prickly pear (Opuntia ficus-indica) is native to Mexico. It readily escapes into dry rocky areas and is firmly established in the bushveld and on krantzes. Eventually it crowds out all other vegetation. Any broken fragment is capable of regeneration.
Water hyacinth (Eichhornia crassipes) is an attractive waterweed from tropical America. It reproduces at tremendous speed and rapidly clogs waterways in warm areas, particularly if the water is slow moving and enriched with dissolved fertilizer and phosphates and nitrates from stock and chicken farming operations. It is easily spread to new areas by boats and by illegal dumping.
Kariba weed (Salvinia molesta) is a sterile hybrid fern originating from Brazil. Kariba weed becomes a pest when it clogs waterways and is easily spread in much the same way as water hyacinth.
There are many other aliens, which are undesirable, at least in certain areas. These include Mauritius thorn (Caesalpinia decapetala), St John’s Wort (Hypericum perforatum), Parrot’s Feather (Myriophyllum spp.), Inkberry (Cestrum laevigatum), Peanut Cassia (Cassia didymobotrya), Jacaranda (Jacaranda mimosifolia), Oleander (Nerium oleander) and Caster Oil (Ricinus communis). Some commercially valuable species can be invasive notably Guava (Psidium guajava), Black Wattle (Acacia mearnsii), Blackwood (Acacia melanoxylon) and Gum (Eucalyptus grandis).
Control methods
The aliens described here, and indeed many others, are invasive because they are difficult to control. Successful control measures have been developed but in many cases only after detailed research and good results can only be expected if attention is paid to detail. For example, some methods are specific to a particular weed or growth form.
Hand pulling
Hand pulling is effective where infestations are small and the invaders shallow rooted. Chromolaena is easily uprooted and so are seedlings of bugweed, wattle, syringa, and sesbania, particularly if the soil is damp. A tractor and chain may be the most suitable way of dealing with saplings.
Mowing
Nearly all invaders will coppice if cut once, but repeated mowing during the growing season causes depletion of root reserves eventually resulting in death. If terrain permits the second and subsequent cuts can be done with a mower. Such treatment favours grass which will then be able to outcompete the weeds and assist in their elimination. Both chromolaena and bramble can be removed by frequent cutting. Cutting can kill Pereskia, but it is essential that the roots are grubbed out too and that they and all cut pieces be burnt on the spot.
Ring-barking
Ringbarking of large trees can be successful but it is slow and is only preferred to felling and other treatments when the latter is impracticable. Every trace of cambium - the growing region between the bark and the hard wood - must be removed from the ring which must be at least 0.5m wide. Note that the subsequent felling of a dried out dead tree is much more difficult that felling the living tree in the first place.
Felling
Felling by itself will not eliminate an invasive tree. Coppice growth usually results and this can be more difficult to control than the original problem. Coppice can be prevented by stripping all the bark off the remaining stump, to below ground level. Alternatively, felling can be carried out in autumn, the timber stacked over the stumps to dry over winter and the whole lot burnt in spring.
Chemical control
Many of the herbicides used in alien control are applied as leaf sprays, which only kills the plant after being translocated to the roots. For this reason, they are not fast acting and indeed it is essential not to kill the foliage before the herbicide has been transported into the plant. Accordingly spray solutions should always be made up as instructed by the manufacturer: Strong solutions will probably be less effective, and certainly more expensive. Efficiency of translocation to the roots is further improved if the herbicide is applied to a large leaf area on actively growing plants. Avoid spraying new, unexpanded growth. In choosing a herbicide there are several points to consider. Firstly, the herbicide should be one registered for use against the weed to be eliminated. Registered herbicides have been rigorously tested and the optimum mode of use determined.
Secondly, it is important to note the level of persistence displayed by the herbicide after application. Residual herbicides preclude immediate regrowth or replanting.
Thirdly, the degree of selectivity of action of the herbicide may be critical. Some kill all plants; others have no effect on non-target species, particularly grasses.
Fourthly, the effect of the herbicide upon animal life must be considered. Since alien weed elimination is usually part of a conservation exercise it can be counter productive if all animal life is killed as well. Some herbicides are dangerous to particular groups of animals. For example, fish are generally more sensitive than mammals and some herbicides should never be used near water.
The state of the weather can greatly influence the success of chemical control. Rain, immediately after a spraying operation, can more or less nullify the treatment. Similarly, heavy dew can dilute the spray and cause it to drip off foliage and reduce its effectiveness. Dust is another factor to consider. Some herbicides deactivate upon contact with soil and have little effect upon dusty foliage. Such herbicides are best applied after rain, as soon as the foliage is dry. Avoid spraying in windy weather since spray drift onto non-target plants may occur.
Some herbicides are effective when painted onto cut tree stumps as an alternative to stripping the bark. It is however, essential that painting be done immediately after felling and that the whole of the cambium is treated.
Which herbicides are suitable for use in conservation areas?
Roundup
Roundup is registered for use against Bugweed, Bramble, Lantana, Prickly Pear, and Water Hyacinth. It kills all green plants, grasses included. It is usually applied as a leaf spray at a concentration of 1-2% in clean water. It is not poisonous to animal life and deactivates upon contact with soil. Land reclamation can thus begin as soon as the target weeds have died. Roundup can also be used as a 2-4% solution to spay onto freshly cut stumps. There are various other brand names on the market with the same active ingredients. Two of these are Mamba and Shaik Down. There are also a number of other trade names on the market.
Garlon
Garlon is registered for use against Bugweed and Chromolaena and is especially effective against Bramble and Chromolaena. It kills only broad-leaved plants and is harmless to grasses and animal life. It does not degrade immediately after application but its residual effects are short lived. Garlon can be used as a leaf spray when diluted with water or as paint when diluted with diesel for cut stumps or ring-barked trees.
Access
This is a highly effective herbicide that is applied, either as a foliar spray or as a treatment of “frilled”, ring-barked or cut stumps. One of its advantages is that it does not affect grass. A similar herbicide is sold under the trade name “Browser”.
Chopper
Chopper is a herbicide that is applied to cut stumps of felled trees and shrubs. It is diluted in water and colours the cut surface a bright pink so that treated stumps are easy to recognise.
Clarosan
Clarosan is registered for use against Kariba weed and Water Hyacinth. It is most effective when used before heavy infestations have accumulated. Its direct effects upon animal life are negligible. However, a large quantity of decaying vegetation in the water will cause deoxygenation and fish deaths can result. Where a dense infestation is present it may be advisable to remove as much as possible of the water weed mechanically prior to spraying, to avoid this side effect. Clarosan has no effect upon reeds and sedges, but will kill any broad-leaved plants at the waterside.
Further details on the use of herbicides should be obtained from the local herbicide representative or from the Weeds Research Unit at Cedara.
Control strategy
Whichever method or combination of methods is chosen there are three general principles to follow:
The first is that light infestations are easier to deal with than heavy infestations. They can also get worse if ignored; heavy infestations may not. So tackle the easiest problem first.
The second is that infestation generally proceeds down hill, particularly when considering riverine vegetation. It is pointless clearing an area when a reservoir of re-infestation exists uphill or upstream. Start at the highest point and work downwards.
The third is that no control operation succeeds the first time. One or more follow-ups are essential. So when attempting to clear a large area piece-meal it is better to make the second effort a follow-up operation on the first area cleared, than to start on a second area. Cleared areas should be inspected at intervals to ensure that alien elimination is complete.
KEY POINTS
- Invading alien plants are a major conservation threat.
- Control measures usually require a carefully planned and implemented program.
- Obtain advice on chemical control from the Weeds Research Unit or your local herbicide representative.
- Follow up operations are essential for complete success.
- Many invaders are still being planted illegally.
- Any plant could become an invader: report new invasions immediately.
Community Focus
Focussing on matters affecting the Community
Conservancy holds well attended meeting
The Lower Mpushini Valley Conservancy held a very well attended meeting at Pandora and Winks Long’s farm, Galago Farm on Saturday, 17 February. The SEA Report for the Mkondeni Stream Catchment Area was discussed and the meeting held the opinion that the report was flawed in that the consultants were also appointed by the developers to produce the EIA report for the proposed development in the area and that they therefore had a vested interest and couldn’t be totally unbiased.
The Open Gardens and Trails weekend that will be held on 17 and 18 March was also discussed. Darlene Bond will, once again, organise the event.
Garth Carpenter hosts another “Campfire Tales” evening
Garth Carpenter hosted another of his popular “Campfire Tales” evening at the African Raptor Centre on Saturday, 24 February.
Prior to the dinner and story time Shannon Hoffman and Tammy Caine entertained the guests with the feeding of the vultures and free-flight demonstrations of a number of owl species and a lanner falcon. Guests were shown how the different species hunt for their prey, some close to the ground and others from a height.
After dinner Garth entertained the guests with a number of tales of his experiences as a game ranger in Zambia and with the then Natal Parks Board. All proceeds from the evening are used for his wild animal rehabilitation programme at “The Sanctuary”, at the Crazy Duck Farm. Garth deserves all the support that he can get from people attending his highly entertaining and informative evenings.
