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REPORT ON THE NATIONAL
BANKRUPT BUSH (Seriphium plumosum)
SURVEY (2010-2012)
Paul Avenant
Production Scientist
January 2015
Department of Agriculture, Forestry & Fisheries
Directorate Land Use & Soil Management
Sub-directorate: Natural Resources Inventories & Assessments
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Executive summary
Bankrupt bush (Seriphium plumosum) is an indigenous woody dwarf shrub that
encroached into mesic grassland and some savannah areas. It competes and
replaces natural rangeland at an enormous rate and scale. Based on current data,
an extrapolation was made to identify probable veld types that might be prone to
encroachment. The results indicate an area of almost 11 million hectares of
rangeland that could be lost for agricultural production. If government does not
regard this problem as serious, and actively get involved in the control thereof, it
might result in a serious threat to national food security.
The Department of Agriculture, Forestry and Fisheries (DAFF) commenced with an
investigation to the extent of this problem during the period of March 2010 to
December 2012. This was done by means of a survey form that was distributed to
farmers in the affected regions and the result of the survey is published in this
report.
The report focuses on the distribution areas of the encroachment, the habitat
preferences of the plant, the control actions farmers used and the impact thereof
on the environment. The four most common approaches are discussed and
evaluated in the report. This includes the use of herbicides, the mechanical
removal of plants and the use of fire, livestock and grazing as additional tools. In
many cases farmers use a combination of these tools to manage the encroachment
effectively. Results indicated however that the use of herbicides, although not the
most environmental friendly method, may be the only solution to make an impact
on the current extent of encroachment. Other approaches may be valuable as tools
in the management of the problem after initial control, but in most cases are too
time consuming and labour intensive to make a real impact at such a large scale.
In the report recommendations are also made in terms of the most effective control
measures and management options based on latest research conducted by
scientific institutions and herbicide companies. Research gaps and priorities are
also further highlighted in the report.
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INDEX
EXECUTIVE SUMMARY...........................................................................1
CHAPTER 1
1. INTRODUCTION…………………………………………………………………………......4
CHAPTER 2
2. LITERATURE RESEARCH…………………………………………………………………..6
CHAPTER 3
3. METHODOLOGIES
3.1 Survey forms……………………………………………………………....………….…9
3.2 Workshops…………………………………………………………………..……….……9
3.3 Field verification………………………………………………………..…………….11
3.4 Reconnaissance surveys……………………………………………..……………11
3.5 Personal communication……………………………………………………….…12
CHAPTER 4
4. RESULTS: GENERAL
4.1 PARTICIPATION IN THE NATIONAL SURVEY………………….……….. 13
4.2 EXTENT OF BANKRUPT BUSH ENCROACHMENT……………………. 15
4.3 PLANT DENSITY………………………………………………………………..…….. 16
4.4 HABITAT
4.4.1 Soils……………………………………………………………………………. 18
4.4.2 Terrain……………………………………………………………..………… 19
4.4.3 Aspect…………………………………………………………………..……. 20
4.4.4 Veld types………………………………………………………....………. 21
4.4.5 Other observations………………………………….………………… 24
4.5 MANAGEMENT HISTORY
4.5.1 Natural veld vs old lands………………………………………….. 25
4.5.2 Animal type……………………………………………………………… 25
4.5.3 Impact on veld and carrying capacity……………………….. 26
4.5.4 Frequency of veld fires…………………………………………….. 26
4.5.5 Years of infestation………………………………………………….. 27
4.6 CONTROL AND MANAGEMENT OF Seriphium plumosum…….. 28
4.6.1 Mechanical control………………………………………………….. 30
4.6.2 Chemical control……………………………………………………… 33
4.6.3 The use of animals to control Bankrupt bush…………… 35
4.6.4 The use of fire to control Bankrupt bush…………………. 38
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CHAPTER 5
5. THE WAY FORWARD
5.1 Holistic approach………………………………………………………………. 39
5.2 Monitoring and research………………………………………………….. 40
5.3 Closing comments…………………………………………………………….. 41
LITERATURE FERERENCES…………………………………………………… 42
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CHAPTER 1
INTRODUCTION
Bankrupt bush (Seriphium plumosum), previously known as Stoebe vulgaris, always has been
part of our indigenous vegetation, but slowly and somewhat unnoticed, encroached large areas
of our precious grassland to keep up to its reputation of leading to many farmer's bankruptcy.
This woody dwarf shrub can grow up to 1m high and is really built for survival. The large crown
may easily cover an area of 1m², over-shadow and pushing out all other species, especially
grasses that need to compete with the extensive root system for water and nutrients. The very
small leaves restrict transpiration to the minimum while the grey to blueish colour reflects the
harsh rays of the sun. Unpleasant smelling volatile oils keep away any browsers and fine seeds
are distributed by the wind in their millions, which can be lying dormant in the ground for more
than five years. Growing points situated just beneath the soil surface ensure the survival of the
plant against any fires or above ground damage.
Many efforts from farmers, government institutions and academic institutions were made to
fully understand and effectively control Seriphium plumosum. Physical removal, chemical
treatment with herbicides and other management tools like fire and grazing were all part of the
“trial-and-error” approach where farmers become poor and discouraged.
Currently this unpalatable, aggressive encroacher can easily be described as the most serious
threat to the mesic grasslands of South Africa. In many cases, farmers lost almost 100% of
natural veld, despite the fact that millions of rand have been spent to control or eradicate this
plant. Until recently, there was very little information available on the actual distribution and
extent of Bankrupt bush encroachment and the reasons why control actions are not successful.
Farmers were often accused of responsible for the Bankrupt bush encroachment on their farms
due to mismanagement of veld. This served as motivation for the Department of Agriculture,
Forestry & Fisheries to undertake this study.
The main objectives of this study were to create a spatial representation of the extent of
Bankrupt bush encroachment in South Africa, to collect information that can inform us about the
habitat preferences and to get a better understanding of all the factors that might have an
influence on the control of this plant. Lessons learned from the success stories as well as failures
will guide us in the way forward to effectively manage this invasion in a more sustainable
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manner, guiding the formulation / adaptation of policies and legislation and provide farmers
with a best practice manual to guide them in the control and management of Bankrupt bush.
Seriphium plumosum encroaching into grassland and destroying productivity:
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CHAPTER 2
LITERATURE RESEARCH
Seriphium plumosum, as described in Van Wyk & Malan (1997) is an indigenous, woody,
perennial shrublet, with greyish, slender and wiry branches which are intricately branched from
the ground. Branches are covered with numerous tufts of small, heath-like leaves of which the
upper surfaces are covered with white woolly hairs. The species light colour, which reflects
sunlight, woolly covering and small leaves, which reduce water loss, are adaptations to survive
long, dry summers. It is an aromatic plant, yielding volatile oil, which is also a protective measure
as the plants are seldom browsed by stock and then only when the plants are still young.
Badenhorst & Reynolds (2004). The flower heads are minute, surrounded by brownish yellow
bracts which enclosed the inconspicuous purple-tipped flowers, and are arranged in large
panicles along the branches. Characteristic globose galls covered with white woolly hairs are
often present on the plants and are frequently mistaken for the flower heads.
The threat of Seriphium plumosum as an encroacher plant has already been studied from the
early 1930’s, as mentioned by Roux (1969). Early researchers perceived that Bankrupt bush
encroachment was mainly due to overgrazing and that its growth was stimulated by fire, but
long term trials at Frankenwald reserve done by Hattingh , proved otherwise. These results, as
was written up by Krupko & Davidson (1961), showed Hattingh found little evidence that
overgrazing is a direct cause of Seriphium encroachment; in fact it actually tends to eliminate it.
Regarding burning, Hattingh finds that winter burning has little effect, but spring and summer
burning prevent establishment of seedlings. Very importantly, Hattingh’s trials also proved that
plots that neither been burnt nor grazed, have been overgrown by the weed.
The reasons for S.plumosum to be such a successful competitor and encroacher are numerous.
Snyman (2010) shows that every shrub produces thousands of seeds annually, which can easily
distributed by wind over large distances to encroach areas which were previously free of S.
plumosum. Marginal soils which were withdrawn from cash crop cultivation in the early eighties
were the first to be encroached and the low organic matter content and none or little
competition creates an ideal habitat. From here, a large seed bank was established from where
adjacent natural vegetation was invaded. Research by Wepener (2007) showed that both
degraded veld as well as veld in a good condition was encroached by S.plumosum under suitable
habitat conditions. According to trials done by Snyman (2010), veld fires stimulate the growth of
S.plumosum seeds and usually lead to an explosion of the seedling population in the following
season.
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Snyman (2010) also mentioned the general opinion of farmers that the conversion from sheep
farming to cattle farming, due to predator problems and stock theft, may have an influence in
the rapid encroachment rate of S. plumosum. This is due to the perception that sheep utilise the
young plants and often browsed the seed tops, which may have controlled its distribution in the
past. Farmers indicated that Merino and Dorper sheep definitely utilises the plants, especially at
young and flowering stages, while cattle tend to avoid browsing the plants.
The habitat preferences of Seriphium plumosum is also still a debateable issue. Although 25 of
the Seriphium species are found in the Cape Fynbos, Seriphium plumosum has a much wider
distribution throughout South Africa. (Badenhorst & Reynolds 2004). According to Roux (1969) it
is commonly accepted that Stoebe vulgaris evolved from S. cinerea (a Karoo species) by
mutation, which changed its character and enable it to invade grassveld. According to research
and observations done by Snyman (2009) in the Thaba Nchu area east of Bloemfontein, it seems
that S.plumosum initially occurred on higher altitudes that were favourable to typical fynbos
vegetation, for example the mountain plateaus of the mountains in the Eastern Free State. From
here, the seed dispersed through winds to lower altitudes where the plants are found today. The
possibility that the tiny seeds of these plants could have easily be spread over large distances by
clinging to animal wool and hides or even through transport like ox-wagen wheels, cannot be
excluded.
Knowledge about the cycles of active plant growth and of reproduction is crucial for effective
control of S. plumosum. Research trials done by Wepener (2007) in the Hartebeeshoek area in
the North-West province showed that the plants are actively growing from August to early
March. The reproductive phase, however, lasts from December to the end of May. This implies
that control should be done before the reproductive phase to prevent seeds from being
dispersed.
Snyman (2012) concludes that Bankrupt bush is very sensitive to high soil-water conditions and
will avoid wetland areas with shallower clay soils. The research of Snyman (2012) also indicates
that Bankrupt bush will avoid habitat of high soil fertility (e.g. lots of organic material or nitrogen
content) and saline or sodic conditions.
Snyman (2012) find a strong relationship between above ground phytomass production (total
amount of living organic plant matter) of grasses and plant density of S. plumosum. According to
Snyman (2012), up to a threshold of 2000 plants ha-1 a drastic reduction in production potential
of grasses occurred. At densities of 5000 plants ha-1, the root distribution of S.plumosum spread
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to such an extent that they compete more or less the same for water and plant nutrients with
the grass sward. If encroachment reaches a level of 2000 plants ha-1, regardless of further
encroachment, it has already decreased the production potential of the rangeland by about
65%.
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CHAPTER 3
METHODOLOGIES
3.1. Survey forms
Initially, it was decided to make use of survey forms to collect as much as possible information in
a relative short period of time. The format for the survey form (Appendix A), was compiled by a
task team, who decided what kind of questions should be asked to collect as much as possible
useful information, but without annoying the farmer who must fill in the questionnaire.
Questionnaires were made available in both English and Afrikaans.
Questions were arranged according to the following four main categories:
a) locality information: to locate properties by means of GPS coordinates or farm
deeds information;
b) encroachment information: to indicate the habitat, extent and density of
encroachment;
c) management history: to indicate management practises that may have an
influence; and
d) control actions: to capture methods, successes and failures of previous attempts
to control the encroachment.
Awareness of the project and distribution of the forms were done through the various provincial
departments of agriculture as well as the organized agriculture. Completed forms were sent to a
central office at the National Department of Agriculture, Forestry and Fisheries, where the data
was captured in a data table. This data table was related to spatial data sets, like the farm
boundary data set, by means of the GPS coordinates or the SG codes of the farm portions to
create a spatial data layer. This spatial layer was then used for creating distribution maps and
GIS data analyses.
3.2. Workshops
Due to the lack of response in certain provinces, it was decided to use farmer workshops as a
new approach. The workshops were arranged through the provincial department of agriculture
and resource auditors from the national department of agriculture. The workshops were mostly
attended by a few selected and leading farmers who farmed in the applicable district for many
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years as well as government officials concerned with natural resource management in the area.
Maps of the area were provided, showing farm boundaries and basic orientation features like
towns and roads. During the workshops, the attendees indicate the extent and density of
Bankrupt bush encroachment by demarcating the areas directly on the maps.
Although this method can give a very good indication of encroachment in a specific area, it still
remains a subjective method, and because the survey forms were not completed, a lot of detail
information about owners, control and management history could not be captured. To fill gaps
in data sets in a short period of time with less effort, the workshops were definitely worthwhile.
It is interesting to see, from the map in Fig 1, that there is a good correlation between the
number of survey forms received from this area and the density of the encroachment. In areas
with a very high density of Bankrupt bush, there was also a very good response to the survey. In
areas less densely encroached, farmers did not realise the seriousness of the problem and did
not bother to respond. Awareness regarding this problem plant is therefore of the utmost
importance in these areas because the quicker the farmer’s responses are to eradicate the
invasion of plants at an early stage, the better the chances are to recover his veld before
irreversible damage is done.
Fig 1. Results from the Aliwal-North workshop in the Eastern Cape.
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3.3. Field verification
Various field visits were undertaken to collect information regarding the habitat, density and
nature of the plant in its environment. To get an estimate of the number of plants per hectare in
different density classes, a typical belt transect method was used. A 100m rope was laid out to
mark the middle of the belt transect. GPS readings were recorded at both the starting and end
points. Two persons, one on each side of the rope, walked along the transect with a 1m wide
aluminum rod each and count all plants within a 1m distance from the rope. This results in a
count of plants per 200m², multiplied by 50 for the number of plants per hectare. In most cases
the Bankrupt bush encroachment are very homogeneous and results are quite accurate for a
specific area.
Fig 2. Counting plants in a belt transect.
3.4. Reconnaissance surveys
As a last resort, information was also captured by means of reconnaissance surveys done while
driving through an area. Known areas with high densities of encroachment but very little
distribution data captured as well as areas identified as probable “border cases” of extent were
identified on maps. Occurrence of plants along roads running through these pre-defined areas,
were captured by means of GPS route logs. The higher the density of the population observed,
the higher frequency of points was captured on the GPS.
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Fig 3. A Bankrupt bush GPS route log done in Limpopo
3.5. Personal communication
Some of the most valuable information was obtained through personal interaction with farmers.
Most farmers participating in the project were involved with Bankrupt bush control for many
years and provide very valuable information on the characteristics of the plant observed under
different conditions and its reaction to different type of treatments. They also gave us access to
encroached land to lay out trials and done some assessments. Especially observations in terms
of animal utilization of plants during different phenological stages and the plants reaction to veld
fires, fertilization and slashing were very helpful. All these pieces of the puzzle helped to put the
bigger picture together in understanding Seriphium plumosum.
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CHAPTER 4
4. RESULTS: GENERAL
The results of this survey will be handled according to the categories on the questionnaire used
during the survey. Overall there was a very good response to the survey, especially from the
Free State province, where organized agriculture actively participated in the process. Some
factors that influenced the response to the survey were:
i) The active involvement of organized agriculture and farmer unions;
ii) Political interference in the process;
iii) The general knowledge of the farmer pertaining to the threats of Bankrupt bush
encroachment;
iv) Lack of communication between different role players;
v) Farmers caution to provide certain information pertaining to their farms and farming
practices;
vi) Some questions on the survey forms were misinterpreted;
vii) The perception of unlimited government funding for control.
4.1 PARTICIPATION IN THE NATIONAL SURVEY
Figure 4 shows all the farms that participate in the national survey by completing the survey
forms. The number of respondents that participate in the survey is shown in Fig.5. Although
survey forms are still submitted due to the continuous nature of the project, a cut-off date was
chosen for data to be used in the final report. This report represents data captured from all
forms received during the period March 2010 – August 2012.
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Fig 4. Extent of farms participated in the national survey
Fig 5. Response to the national survey
In the survey form, farmers were asked to give an estimate of the hectares of their farms that
have been encroached with Bankrupt bush. The total area of the 1491 farming units that
participated in the survey was 423 125 ha of which a total of 150 202 ha (35.5%) was indicated
to be encroached by Bankrupt bush.
806
582
1491
0
200
400
600
800
1000
1200
1400
1600
Survey forms Owners Farming units
Response to national survey
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4.2 EXTENT OF BANKRUPT BUSH ENCROACHMENT
By merging all spatial data collected by means of the methods described in chapter 3, a map can
be compiled showing the actual distribution of Bankrupt bush encroachment in South Africa. It is
mostly the Highveld grassland areas, as described by MUCINA & RUTHERFORD 2006, which are
affected the most. The core area of distribution can be described as follow:
Limpopo province: mainly restricted to the Waterberg district
Gauteng province: mainly the eastern Highveld areas
Free State province: the eastern part of the province, about a third of the province
Eastern Cape province: mostly from Aliwal-North south to Dordrecht
North-West province: mostly areas east of Wolmaransstad
KwaZulu-Natal province: limit to the Northern sandy grassland areas
Mpumalanga province: Western Highveld and sour-grassveld areas.
Further analyses of the distribution data can be found in Chapter 4 where the habitat of
Bankrupt bush is described in more detail.
Fig 6. Distribution of Seriphium plumosum in South Africa
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4.3 PLANT DENSITY
Plant densities can be mainly obtained through two methods. The first is by an actual physical
survey counting plant numbers in a known area. The second is by visual assessment, walking
through a stand of Bankrupt bush and observe and try to correlate canopy cover to number of
plants.
The methodology for counting Bankrupt bush plants in a belt transect was described in chapter
two. In some severe cases plant densities of more than 40 000 plants per hectare were counted.
The following table show some results of actual assessments done on some Free State farms.
Table 1. Plant density for certain Free State transects
District Site Latitude Longitude Plants/ha
Zastron Commonage 1 S 30° 17’ 17,5” E 27° 04’ 35.0” 15 600
Zastron Commonage 2 S 30° 17’ 19,6” E 27° 04’ 45.0” 20 950
Ladybrand Johannasrust S 29° 24’ 44.9” E 27° 15’ 39.7” 15 000
Thaba Nchu Rietfontein S 29° 24’ 36.3” E 26° 56’ 06.8” 12 500
Harrismith Elm Villa 1 S 28° 04’ 45.0” E 28° 58’ 50.5” 7 550
Harrismith Elm Villa 2 S 28° 04’ 45.6 E 28° 58’ 54.1 4 350
Heilbron Cyferpan S 27° 23’ 16.3” E 28° 00’ 45.3” 20 000
Heilbron Holfontein S 27° 30’ 32.6” E 28° 06’ 50.4” 26 100
For the analyses of survey data, actual plant densities (plants/ha) as obtained through field
surveys, were correlated to the subjective, visual plant coverage classes used on the survey
forms. The following results were obtained for moderate size mature plants, each covering an
area of ± 0.25 m².
Table 2. Canopy cover classes relates to plant densities
Canopy cover
Plant Density
(plants/ha)
25% < 10 000
50% 10 000 - 20 000
75% 20 000 - 30 000
100% >30 000
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Visual assessments of plant densities can be very misleading because of the actual age and
crown diameter of plants. An area covered with very large, mature plants may have a high
canopy cover, but a lower than estimated density, while lots of seedlings may give the
impression of a low canopy cover, but actually have a very high plant density. For these reasons,
the information in table 2 can only be seen as broad guidelines when used in visual estimates,
and need to be verified by actual field surveys.
In contradiction to the research done by Snyman (2012), the grass sward as well as species
biodiversity, seem to survive remarkably well under plant densities of up to 20 000 plants ha-1.
Veld subjected to this intensity of encroachment, also shown the ability to recover at a very fast
rate, when the encroacher shrubs are removed, and can regain above ground phytomass
production in as little as two growing seasons under normal rainfall conditions.
To help farmers with visual assessments, plant density classes were developed for the survey
forms, accompanied by diagrams to help the respondent to visualize the distribution and density
of plants in the veld. Four classes were used e.g. 25%, 50%, 75% and 100% canopy cover. Figure
7 shows the schematic diagram and figure 8 the results from the 1475 farming units that
answered the question. In hindsight, it should have been more effective to provide more cover
classes on the survey forms. Many farmers created their own coverage classes when answering
the question, making it very difficult to analyse the data afterwards.
25% 50% 75% 100%
Fig 7. Density class diagrams
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Fig 8. Percentage of farming units in each density class
4.4 HABITAT
4.4.1. Soils
The general perception that S.plumosum only prefers well drained, sandy soils is also a much
debateable issue. The research done by Snyman (2012), was mainly restricted to the Free
State province, where, as indicated, Bankrupt bush tend to occur on well drained soils. From
the survey results, as shown in figure 9 it is clear that, although 85% of encroachment was
found on well drained soils in the sandy and loamy classes, there was also a 15% reported on
clay soils, and in some cases, even in wetland areas. In the Limpopo province, however, a
total change of character was observed, where S. plumosum tend to invade sandy wetland
areas and drainage lines. This behaviour poses a great threat to the sensitive ecosystems of
the Waterberg catchment and biosphere reserve.
32.88
44.61
20.81
1.69
Percentage farming units per plant density class
25% 50% 75% 100%
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Fig 9. Occurrence of S.plumosum per soil texture class
4.4.2. Terrain
As illustrated by a diagram on the survey forms, the land owners were asked to indicate the
terrain type where Bankrupt bush mainly occurs. Four terrain types were indicated namely:
i) Mountain crests or plateaus
ii) Mountain slopes
iii) Valley bottoms or depressions
iv) Flat or slightly undulating areas
The reason behind this question was to test the hypothesis that Bankrupt bush mainly
occurs on mountain slopes with good drainage. The results from the survey are illustrated in
figure 10. As expected, S. plumosum prefers mountain slopes and flatter landscapes as ideal
habitat, there wasn’t a significant difference compared to mountain crests, although this
was also expected compared to the hypothesis of Snyman (2009). What was, however, a big
surprise, was that 18% of plants occurred in valley bottoms or depressions. This is
contradictory to the belief that S.plumosum will avoid areas where water logging or seasonal
wetness may occur.
15%
59%
26%
Percentage occurrence of Seriphium plumosum per
soil texture class
Sand Loam Clay
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Fig 10. Percentage occurrence of S.plumosum on different terrain types
4.4.3. Aspect
In most literature on the habitat of S.plumosum, it was observed that Bankrupt bush favours
certain aspects. To test this hypothesis, a question on aspect was included into the
questionnaire. This question was unfortunately not as successful as the previous question on
terrain types. Many farmers did not understand the concept of aspect and either did not
answer the question at all or indicate all the options as possibilities. Results of the analysed
data are illustrated in figure 11.
From the results of the 1411 responses to this particular question it was evident that there
was no significant correlation between the habitat preference of Bankrupt bush and the
different aspects. The fact that the occurrence of Bankrupt bush on both of the opposite
aspects, for example North-South and East-West, were almost identical, illustrates the fact
that aspect is not such a determining factor as that was thought initially. In certain areas a
specific aspect may be favoured by Bankrupt bush, but after establishment, it will also
spread into adjacent areas of different aspect.
19%
30%
18%
33%
Percentage occurrence of Seriphium plumosum on different terrain types
Mountain crests orplateaus
Mountain slopes
Valley bottoms ordepressions
Flat or slightly undulatingareas
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Fig 11. Percentage occurrence of S.plumosum on different aspects of the landscape
4.4.4. Veld types
By using the distribution data obtained from the survey forms and additional observations, a
good correlation was found between the occurrence of Bankrupt bush and certain veld
types. The Vegetation types from Mucina & Rutherford (2006) were used for this exercise.
57 Vegetation types were identified as probable habitat where S.plumosum might occur.
From these vegetation types, 77.2% were from the Grassland biome and 22.8% from the
Savanna biome. In the Grassland biome, four Bioregions were involved namely the
Drakensberg Grassland Bioregion, the Dry Highveld Grassland Bioregion, the Mesic Highveld
Grassland Bioregion and the Sub-Escarpment Grassland Bioregion. The Savanna biome only
involved one Bioregion - the Central Bushveld Bioregion. Table 3 is showing the vegetation
types as well as the related biomes and bioregions.
N 16%
S 16%
W 11%
E 11%
NE 13%
NW 12%
SE 11%
SW 10%
0%
Percentage occurence of Seriphium plumosum on different
aspects of the landscape
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Table 3 Biomes, Bioregions and Vegetation types that includes S. plumosum
BIOME BIOREGION VEGETATION TYPE BOOKCODE
Grassland Biome Drakensberg Grassland Bioregion Stormberg Plateau Grassland Gd 3
Grassland Biome Drakensberg Grassland Bioregion Southern Drakensberg Highland Grassland Gd 4
Grassland Biome Drakensberg Grassland Bioregion Northern Drakensberg Highland Grassland Gd 5
Grassland Biome Drakensberg Grassland Bioregion Lesotho Highland Basalt Grassland Gd 8
Grassland Biome Dry Highveld Grassland Bioregion Karoo Escarpment Grassland Gh 1
Grassland Biome Dry Highveld Grassland Bioregion Aliwal North Dry Grassland Gh 2
Grassland Biome Dry Highveld Grassland Bioregion Besemkaree Koppies Shrubland Gh 4
Grassland Biome Dry Highveld Grassland Bioregion Central Free State Grassland Gh 6
Grassland Biome Dry Highveld Grassland Bioregion Winburg Grassy Shrubland Gh 7
Grassland Biome Dry Highveld Grassland Bioregion Bloemfontein Karroid Shrubland Gh 8
Grassland Biome Dry Highveld Grassland Bioregion Vaal-Vet Sandy Grassland Gh 10
Grassland Biome Dry Highveld Grassland Bioregion Vredefort Dome Granite Grassland Gh 11
Grassland Biome Dry Highveld Grassland Bioregion Vaal Reefs Dolomite Sinkhole Woodland Gh 12
Grassland Biome Dry Highveld Grassland Bioregion Klerksdorp Thornveld Gh 13
Grassland Biome Dry Highveld Grassland Bioregion Western Highveld Sandy Grassland Gh 14
Grassland Biome Dry Highveld Grassland Bioregion Carletonville Dolomite Grassland Gh 15
Grassland Biome Mesic Highveld Grassland Bioregion Zastron Moist Grassland Gm 1
Grassland Biome Mesic Highveld Grassland Bioregion Senqu Montane Shrubland Gm 2
Grassland Biome Mesic Highveld Grassland Bioregion Eastern Free State Clay Grassland Gm 3
Grassland Biome Mesic Highveld Grassland Bioregion Eastern Free State Sandy Grassland Gm 4
Grassland Biome Mesic Highveld Grassland Bioregion Basotho Montane Shrubland Gm 5
Grassland Biome Mesic Highveld Grassland Bioregion Frankfort Highveld Grassland Gm 6
Grassland Biome Mesic Highveld Grassland Bioregion Northern Free State Shrubland Gm 7
Grassland Biome Mesic Highveld Grassland Bioregion Soweto Highveld Grassland Gm 8
Grassland Biome Mesic Highveld Grassland Bioregion Tsakane Clay Grassland Gm 9
Grassland Biome Mesic Highveld Grassland Bioregion Egoli Granite Grassland Gm 10
Grassland Biome Mesic Highveld Grassland Bioregion Rand Highveld Grassland Gm 11
Grassland Biome Mesic Highveld Grassland Bioregion Eastern Highveld Grassland Gm 12
Grassland Biome Mesic Highveld Grassland Bioregion Amersfoort Highveld Clay Grassland Gm 13
Grassland Biome Mesic Highveld Grassland Bioregion Wakkerstroom Montane Grassland Gm 14
Grassland Biome Mesic Highveld Grassland Bioregion Paulpietersburg Moist Grassland Gm 15
Grassland Biome Mesic Highveld Grassland Bioregion KaNgwane Montane Grassland Gm 16
Grassland Biome Mesic Highveld Grassland Bioregion Lydenburg Montane Grassland Gm 18
Grassland Biome Mesic Highveld Grassland Bioregion Sekhukhune Montane Grassland Gm 19
Grassland Biome Mesic Highveld Grassland Bioregion Lydenburg Thornveld Gm 21
Grassland Biome Mesic Highveld Grassland Bioregion Waterberg-Magaliesberg Summit Sourveld Gm 29
Grassland Biome Sub-Escarpment Grassland Bioregion Low Escarpment Moist Grassland Gs 3
Grassland Biome Sub-Escarpment Grassland Bioregion Northern KwaZulu-Natal Moist Grassland Gs 4
Grassland Biome Sub-Escarpment Grassland Bioregion Northern KwaZulu-Natal Shrubland Gs 5
Grassland Biome Sub-Escarpment Grassland Bioregion KwaZulu-Natal Highland Thornveld Gs 6
Grassland Biome Sub-Escarpment Grassland Bioregion Income Sandy Grassland Gs 7
Grassland Biome Sub-Escarpment Grassland Bioregion Drakensberg Foothill Moist Grassland Gs 10
Grassland Biome Sub-Escarpment Grassland Bioregion Tsomo Grassland Gs 15
Grassland Biome Sub-Escarpment Grassland Bioregion Tarkastad Montane Shrubland Gs 17
Savanna Biome Central Bushveld Bioregion Zeerust Thornveld SVcb 3
Savanna Biome Central Bushveld Bioregion Dwarsberg-Swartruggens Mountain Bushveld SVcb 4
Savanna Biome Central Bushveld Bioregion Norite Koppies Bushveld SVcb 7
Savanna Biome Central Bushveld Bioregion Moot Plains Bushveld SVcb 8
Savanna Biome Central Bushveld Bioregion Gold Reef Mountain Bushveld SVcb 9
Savanna Biome Central Bushveld Bioregion Gauteng Shale Mountain Bushveld SVcb 10
Savanna Biome Central Bushveld Bioregion Andesite Mountain Bushveld SVcb 11
Savanna Biome Central Bushveld Bioregion Central Sandy Bushveld SVcb 12
Savanna Biome Central Bushveld Bioregion Loskop Mountain Bushveld SVcb 13
Savanna Biome Central Bushveld Bioregion Loskop Thornveld SVcb 14
Savanna Biome Central Bushveld Bioregion Springbokvlakte Thornveld SVcb 15
Savanna Biome Central Bushveld Bioregion Western Sandy Bushveld SVcb 16
Savanna Biome Central Bushveld Bioregion Waterberg Mountain Bushveld SVcb 17
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From this layer of probable suitable habitat for S.plumosum, further refinement in ArcMap
was done by subtracting the areas of water bodies, buid-up areas, plantations, open cast
mining areas and cultivated land. The data from the 2005 LandCover Change project was
used for this analysis. After this refinement, the layer shows a probable 11 million hectares
of rangeland that are either already encroached or suitable for probable encroachment.
Figure 12 is showing the probability map for Bankrupt bus encroachment.
Fig 12. Rangeland probability map for distribution of S.plumosum
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4.4.5. Other observations
Some observations that were also mentioned in the survey were:
i ) Old lands
It seems that the infestation of old, unutilized cultivated fields is playing an important role in
the distribution patterns of Bankrupt bush. In the early 1980’s government launched a huge
project, trying to stop the cultivation of land with a marginal potential for crop production.
Instead of rehabilitate these areas back to veld or planted pastures, many farmers just left
the areas to let nature go its course. This provided an ideal opportunity for the opportunistic
Bankrupt bush to colonise these areas without any competition of neighbouring plants, as in
the case with natural veld. From here the plants establish strong colonies and seed banks
that invade adjacent natural veld. In the survey, 61% of farmers indicated that the Bankrupt
bush started on old cultivated fields.
ii) Road reserves
Road reserves provide a safe haven for Bankrupt bush seedlings to establish. Especially road
reserves along smaller arterial roads where the road reserves are not frequently being
slashed or burned. Many farmers complained about unattended road reserves that re-
invade previously cleared areas. On the contrary, road reserves that are frequently burned
or slashed seem to have less encroachment than on the other side of the fence.
iii) Natural veld with a good veld condition
Seriphium plumosum will establish itself also in natural veld with a good veld condition, but
in many cases infestation is well correlated to veld that is under-utilized. Many farmers
believed that, by just leaving veld to rest it will suppress the Bankrupt bush by competition.
Unfortunately the opposite is true. Veld that is under-utilised and has a good canopy cover
provides a very safe haven for the vulnerable seedlings of the Bankrupt bush to establish.
Veld that is moderately grazed tends to have less Bankrupt bush plants and also a poor
seedling survival rate.
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4.5. MANAGEMENT HISTORY
4.5.1. Natural veld vs old lands
One of the most frequently asked questions by farmers were if it’s the farmer’s fault that
bankrupt bush invades his natural veld. This question is not that easy to answer. In some
cases, by overgrazing veld, areas with little competition will make it easy for Bankrupt bush
to establish, because it then acts as a pioneer plant. Veld that are under-utilise will also
create a safe haven to seedlings. Taking this into account, one may argue that good veld
management practices may decrease the risk of Bankrupt bush encroachment. However,
one of the most mentioned problems in the survey was the fact that a farmer has no
defence against dense populations of Bankrupt bush in the adjacent areas to his farm. In this
case, no matter how perfect his veld management is, the Bankrupt bush will eventually find
its way into his veld by means of its millions of air born seeds. In mostly all cases, the major
pattern of distribution of Bankrupt bush is in the same direction as the prevailing winds in an
area. As already mentioned in 4.4.5.i, old cultivated fields that were left unattended also
created suitable habitats and farmers need to establish planted pastures on these areas.
4.5.2. Animal type
The purpose of this question was just to establish if there was any correlation between a
specific type of livestock and the problem of Bankrupt bush encroachment. The impact of
different types of livestock will be handled in more detail in Chapter 5 dealing with control
measures through the use of animals. The graph in figure 13 shows the results from the
survey on the question of the history of animal presence in the infested camps.
Fig 13. Animal types kept on S. plumosum encroached veld
63.44%
26.67%
9.01% 0.54% 0.34%
Animal type on encroached veld
Cattle
Sheep
Game
Horses & Donkeys
Goats
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4.5.3. Impact on veld and carrying capacity
The purpose of question C, under management history, was to get an idea of the impact of
Bankrupt bush encroachment on natural veld, in particular, the grass sward. The farmers
were asked to indicate the long term grazing potential of the veld (as in a good veld
condition), and then the carrying capacity of the veld after the Bankrupt bush encroachment
became a problem. The preferred units was ha/Large Stock Unit (LSU). In the majority of
cases, farmers lost between 30 – 60 % of their grazing capacity. As the Seriphium plumosum
plants mature, they suppress natural vegetation until the area became a “green desert” with
nothing else than Bankrupt bush alone. In this way it does not only decrease the carrying
capacity of veld, but also destroys the plant biodiversity of the area. Large plants may easily
cover up to 1m² with their canopy, blocking out sunlight necessary for other plant species to
survive while also depriving other plants from valuable moisture and nutrients with its
extensive root system.
This loss of veld and carrying capacity has detrimental effects on the economics of a farming
enterprise. Let’s look at an example of a farmer who has a farm with 1000 ha of natural
rangeland with a long term grazing potential of 6 ha/LSU, it means that the farmer can keep
about 166 LSU on his farm. If a Bankrupt bush encroachment of 50% decreases the carrying
capacity to 12 ha/LSU, the farmer can now only keep 83 LSU on the land. This results in a
50% loss in income. According to the June 2014 price list for live animals, from the Feedlot
Association of South Africa, a price of R20.36/kg is paid. The income for a large stock unit
(LSU) of 450kg is therefore R9 162.00 per LSU. This adds up to a possible annual loss of
R760 446.00 .
Although this example is only based on a farm of 1000 ha, one can imagine what the figure
will be if all of the 11 million hectares of predicted habitat only lost half of its potential. In
the mean while there are already a lot of farms that lost 100% of rangeland production.
Taking all of this into account, no other natural disaster like drought, fire or pest and disease
have such an impact on the biodiversity of the grassland and savanna biomes and the stock
farming industry.
4.5.4. Frequency of veld fires
This question (History D) was aimed at the history of burning frequency on a farm and its
probable impact on S. plumosum. A very wide range of answers were received, varied from
almost never to every year. Overall it doesn’t seem if there was any correlation between the
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frequency of veld fires and the occurrence of S. plumosum. Many farmers indicated that fire
tend to increase the numbers of Bankrupt bush plants and stimulates the germination of
seedlings. The actual impact of fire on Bankrupt bush will be discussed in Chapter 5 under
the heading of fire as management tool.
4.5.5. Years of infestation
This question (History E) gives a very good indication of the timeframe of this problem. A lot
of farmers indicated that S. plumosum has been present on their farms for many years, but
only became a serious problem during the last 10 years. Farmers initially didn’t bother to
eradicate the plant because it didn’t occur in such high numbers (as it is currently the case)
and did not have such a detrimental effect on rangeland. By the time that the farmer starts
noticing a problem, it was already too late to implement effective control measures.
Fig 14. Number of years farms have been encroached by S.plumosum
20%
35% 15%
19%
1% 5%
5%
Number of years farms have been encroached by S.plumosum
1 - 5 yrs
6 - 10 yrs
11 - 15 yrs
16 - 20 yrs
21 - 25 yrs
26 - 30 yrs
> 30 yrs
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4.6. CONTROL AND MANAGEMENT OF Seriphium plumosum
In the national survey, in the section pertaining to Control Actions, 80% of farmers indicated
that they already attempted to eradicate Bankrupt bush on their property, without any
financial assistance from government. 20% of farmers however indicated that they have
never attempted to control Bankrupt bush. Many farmers spend lots of money on fruitless
efforts to control Bankrupt bush because they did not follow a few simple guidelines to be
successful in their effort.
The control of S. plumosum can be done in many ways; some are more successful than
others. In most cases it is the best to use a combination of control methods, firstly to
reduce the number of plants drastically and thereafter manage the situation to keep
numbers low or eventually eradicate the infestation permanently. This section will illustrate
some of the success stories and some of the less successful stories as captured in the survey
section on control actions.
In general a few important points on control of any invasive plant species:
Timely follow up is critical. A common mistake is to clear too large area initially and budget
and time run out to do timely follow up. The golden rule is to plan your control programme
over a three year or longer period and budget accordingly. First do required follow up before
clearing new areas. Initial clearing without timely follow up invariably results in denser
infestations if left unattended.
i) Always try to keep un-infested areas clean.
Rather concentrate initial control efforts on small and new colonies at the perimeter of an
infestation than to spend too much effort on the centre, dense infestation, where all
natural veld are already lost.
Fig 15. Strategy to control colonies of bush encroachment.
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ii) Supervision is extremely important.
Almost all the cases of failure are in some way connected to poor supervision of control
teams. Supervisors need to be on-site all day and need to check if all areas or plants are
treated, if herbicides are prepared correct and if correct dosages are applied. In manual
control, supervisors must make sure that equipment is in good working order and that it is
used correctly.
iii) Training.
Training will always be an important factor in any control action. Firstly make sure that the
trainers are certified and registered trainers to provide the specific training. Also ensure
that everyone involved in the control, are properly trained and are capable to do what is
expected from them.
iv) Safety
Safety of workers must always be a number one priority. Safety training must highlight all
probable risks to the workers and how they can avoid it. All safety equipment must be
issued and workers must sign that they received it and know how to use it.
The next section in the survey focused on the control methods used in the control of
Bankrupt bush. The four options were:
i) Mechanical
ii) Chemical
iii) Grazing
iv) Fire
Many farmers also indicated that they have used different combinations of the above
mentioned methods. The results from the survey are shown in the graph below:
Fig 16. Control methods used by farmers
35%
24%
22%
19%
Control methods used by farmers
Mechanical
Chemical
Grazing
Fire
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4.6.1. Mechanical control
Mechanical removal of Bankrupt bush can either be done by hand or through machinery like
tractors to disk, plough or slash. Removal by hand is usually done with a pick-axe (“bospik”)
or hoe. In many cases, an ordinary hoe is too light to really cut deep enough to remove the
burl of the stem, which is situated just beneath the soil surface. The wide hoe blade just cut
off above-ground stems, leaving the growth points to start regrowth within a week.
Fig 17. Above-ground stems cut off with a hoe.
Fig 18. Growth points started to sprout from the underground burl.
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Fig 19. The hoe (left) is not as successful as the pick-axe “bospik” (right) to remove plant
roots deep enough.
From all the mentioned methods used by farmers for mechanical removal of plants, the
chopping out of plants by means of a hoe or pick-axe was by far the most popular method
used. This method was mainly limited to plants that invade natural veld with low plant
densities of up to 5000 plants/ha. For higher plant densities it is more efficient to use
herbicides. Disking and ploughing were mainly used in previously cultivated fields and many
farmers also indicated that they established these fields with planted pastures afterwards. It
seems however that some planted pastures with less dense growth forms, like Digitaria
eriantha, may be easily invaded by Bankrupt bush, especially in the first year of
establishment. Slashing of plants was also used by some farmers and although this method
is not removing the plant, many case studies indicated that plant numbers will decrease
through continuous slashing.
Fig 20. Mechanical methods used by farmers to control Bankrupt bush.
83%
7%
10%
Mechanical methods used by farmers
Hoe or pick
Slash
Disc & Plough
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When removing plants mechanically, some farmers tend to pile-up the chopped out plants.
This is for obvious reasons, because it made it easy to see where control has been done and
what the progress is but unfortunately there is also a few disadvantages. Seeds are
dispersed to other areas as plants are dragged to the pile. In many cases, these piles are
then burned. The heat of such an intense fire is sterilizing the soil beneath and these open
patches of sterilized soil will take a very long time to restore, giving ample opportunities for
other weeds and invasive plants to establish there. Even if piles are not burned, but only left
as such, they become a very serious fire hazard. In the event of an unplanned veld fire, these
piles will create their own drafts, causing the uprooted plants to be scattered all over the
place as flying torches that will ignite anything they touch.
Fig 21. Piling-up of uprooted Bankrupt bush.
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4.6.2. Chemical control
Chemical control still remains the most cost effective way to control dense infestations of
Bankrupt bush. The use of herbicides in the natural environment will always be regarded as
a sensitive issue, and in the case of Bankrupt bush control it is no exception. Unfortunately
environmentalists always defend their position using the cases of wrong application or
dosages that caused major damage to the environment. On the other side are the herbicide
companies claiming years of research and experience developing safe and effective
herbicides. The other major factor that influences herbicide control is cost. Most farmers
used cheaper herbicides, not always developed for the results that the farmer has in mind.
When analysing the options of herbicide control available for S. plumosum there are mainly
two active formulas used namely Tebuthiuron and Metsulfuron;
Tebuthiuron is a non-selective broad spectrum herbicide of the urea class. It is used in a
number of herbicides manufactured by Dow AgroSciences, and is sold under several trade
names, depending on the formulation. The most popular trade names used in South-Africa
are Molopo and Limpopo and are available as granules or suspensions. Tebuthiuron is a
systemic herbicide absorbed by the roots and inhibiting photosynthesis. Application is by
means of aerial or ground broadcast or as spot application by means of a knapsack sprayer
or granules per plant. After application, rain is needed to wash the herbicide into the soil,
reaching the plant roots from where it is absorbed. It takes up to 24 months for large plants
like trees to die and about 12 months for a shrub like Bankrupt bush. Over dosage is a big
risk, especially with spot application of granules. Great care need to be taken to prevent
over dosage and farmers must make sure that the over-all application of granules per area is
not too high. Over dosage can lead to sterilising the soil and dying of all plant life, leaving
areas of bare soil with a high risk of erosion (DU TOIT 2012). Tebuthiuron is a very effective
herbicide recommended to quickly get rid of large and dense infestations of Bankrupt bush.
One of the biggest benefits is the 3 year active period of the herbicide that will also kill off
any seedlings germinating during this period. One of the biggest challenges with spot
application is not to miss any plants. A colour stain is added to the herbicide making it easy
for the controller to see which plants have been treated. Spot application is much easier
after most of the old and moribund material was removed and enough new growth achieved
to absorb a sufficient amount of herbicide that can be trans-located to the roots. Regrowth
after a burn provides an excellent opportunity. Spot application is only recommended for
plant densities of less than 4000 plants/ha. Denser populations can be treated by means of
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broadcasting of granules or spraying with tractor sprayers or in more inaccessible areas by
means of aerial application with a light aeroplane.
Fig. 22 Tebuthiuron as a suspension (left) or granules (right)
Metsulfuron-methyl is a residual sulfonylurea herbicide that kills broadleaf weeds and some
annual grasses. It is a foliar applied systemic compound which inhibits cell division in shoots
and roots. It has no residual activity in soils, allowing it to be used frequently. It has very low
toxicity to mammals, birds, fish, and insects. Metsulfuron must be sprayed onto the foliage
of actively growing plants with a single application during the active growing period
(October to April) and preferably during the late summer (January to end April) but before
the onset of winter. Removing the dead foliage of S. plumosum by means of slashing or
burning before application will improve uptake of the herbicide and result in better control.
Slashing can however result in the release of ample seed, which will have to be controlled
the following season. Trade names of Metsulfuron-methyl in South-Africa such as Brush-off
and Climax are very popular with farmers because they are usually not that expensive, but
farmers do not always take into account the fact that they need to apply the herbicide for at
least 3 consecutive years to achieve the same results as for example with Tebuthiuron. This
adds up to quite an expensive exercise. One of the big challenges with the use of
Metsulfuron is that it also required large quantities of water to prepare the suspension,
which in some remote areas are not always possible. Metsulfuron has however a very
important role to play as a follow-up herbicide after the use of Tebuthiuron. Because of the
harsh impact of Tebuthiuron on the environment and its residual build-up in soil, it is not
recommended to be use for two consecutive cycles of treatment in an area. Metsulfuron
provide a good and safe substitute to control the remaining few plants that managed to skip
the Tebuthiuron treatment.
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Fig 23 . Some popular herbicide trade names
Other herbicides used by farmers were Access, Browser and Garlon from the Triclopyr and
Picloram active ingredients. Roundup from the Glyphosate active ingredients and
Bushwacker and Savanna from the Bromacil active ingredients. Although salt will kill
Bankrupt bush, the negative impact on the environment and the danger of salination of soils
creates a much bigger environmental threat than the Bankrupt-bush itself. It is therefore not
recommended at all for farmers to use salt in the control of Bankrupt-bush.
The following survey results shows which herbicide products were the most popular with
farmers:
Table 4. Herbicides used by farmers to control S.plumosum
ACTIVE INGREDIENT TRADE NAME PERCENTAGE
Metsulfuron-methyl Romex 8.25%
Climax 17.75%
Brush-off 31.81%
GROUP TOTAL 57.81%
Tebuthiuron Molopo 28.30%
Limpopo 2.81%
Grazer 0.18%
GROUP TOTAL 31.29%
2,4 D Ester 2,4 D Ester 4.57%
Tebuthiuron x Bromacil Savanna 1.05%
Bromacil Bushwacker 0.18%
Glyphosate Round-up 2.11%
Sodium chloride Salt 2.99%
HERBICIDES USED BY FARMERS
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4.6.3 The use of animals to control Bankrupt bush
Animals will usually not browse on Bankrupt bush, due to the presence of bitter tasting
essential oils. However, a lot of farmers indicated that cattle will browse the plants
occasionally and that sheep quite often will browse on the flowering tops of the plants. For
this reason, many farmers reason that the Bankrupt-bush encroachment increased when
farms shifted their farming commodities from large stock to small stock.
Although browsing animals will suppress the growth of Bankrupt bush, it will rarely manage
to kill the plants, but their hoof action turned out to destroy quite a significant number of
seedlings, and thus contribute to control. On the contrary, to withdraw animals from
infested veld and think that the grass sward will eventually suppress and kill Bankrupt bush,
is not only a misperception but can even worsen the situation. The dense grass sward will
create a safe haven for the vulnerable seedlings to survive and become strong plants. The
best results will be achieved by following normal grazing regimes while controlling Bankrupt
bush. Some game species like Rhinoceros and Eland will often browse Bankrupt bush as part
of their normal diet.
It is also proven that Bankrupt bush is sensitive to high organic content in soils. The animal
dung and urine provides an unfavourable environment for Bankrupt bush to flourish in, and
especially for seedlings to survive. Some farmers who have access to huge amounts of
animal dung, for example feedlots, started to cover the Bankrupt bush infested veld with
about 4 t/ha of animal dung. This will only help to keep the plants within controllable limits,
but will probably never eradicate all plants. The question however arises what the impact of
this practice will be on the veld itself and underground water reserves after leeching of
harmful nitrates into the soil.
Fig 24. Animal dung
and high intensity
grazing (left camp)
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The photograph above shows a very clear fence line effect after the camp on the left was
treated with 4t/h of animal dung and also heavily trampled and grazed through high
intensity grazing. Although it looks like the Bankrupt bush disappear, many plants are still
present, but only overshadowed by a very healthy and vigorous grass sward.
It seems that continuous defoliation of Bankrupt bush may contribute to suppress the plants
and that numbers will eventually decrease. If animals are not an option, even mechanical
defoliation may be used. The photograph below shows an area in a game reserve, where the
manager slashes the Bankrupt bush twice during the growing season. This also will not
remove the plants in total, but definitely decrease its numbers.
Fig. 25 Natural veld slashed to suppress Bankrupt bush
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4.6.4 The use of fire to control Bankrupt bush
Fig 26. Burning Bankrupt bush creates a very high intensity fire.
Fig 27. Bankrupt bush sprouts just one week after burning.
The two pictures above shows the amazing ability of Bankrupt bush to survive a fire. Due to
the growing points that are safely hidden below the soil surface, the plant manages to
escape death by fire without any trouble. It is thus important to note that a farmer will
never be able to totally eradicate Bankrupt bush only by the use of fire, but it can still be a
very handy tool to assist in control. Especially in very dense stands of old and moribund
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plants, fire can be very helpful to remove the above ground plant material in order to ease
access into the area for control teams, either using herbicides or chopping out plants. New
growth can easily be seen and individual plants can easily be identified to be hoed out or
treated with herbicides. Herbicides are also absorbed much more efficient by the new
growth and less liquid application is wasted on moribund material. It is however extremely
important to burn only in safe conditions and when ample fire fighters and equipment are
on standby. Because of the essential oils in Bankrupt bush, it creates an extremely hot and
intense fire that is almost impossible to stop once it is started. Very broad firebreaks and an
adequate supply of water will be needed to burn a block of Bankrupt bush safely.
Just remember that fire will always be a very detrimental tool. It removes all organic debris
and totally denudes the soil compared to slashing that leaves an organic blanket on the
surface that retains moisture, feeds the soil and suppresses establishment of bankrupt bush
seedlings.
Some research also indicated that burning will stimulate seed germination, and many times
after a burn, huge population explosions of seedlings are noticed. This creates a good
opportunity to treat the area with a herbicide that will have a long after effect, or using
animals to trample the seedlings and browse on new growth.
Research also indicates that a burn during early summer (November / December) will cause
the most damage to mature plants. This is also unfortunately the time of the year that a
burn will do the most harm to the grass sward. In dense stands of Bankrupt bush, where
very little of the grass sward is left, it is an option, but otherwise other options may be
considered. Burning in spring will cause the greatest damage to seedlings.
5. THE WAY FORWARD
5.1. Holistic approach
If one looks at the current situation of Bankrupt bush encroachment, the most honest
conclusion will be that we will never totally eradicate this problem. Seriphium plumosum is
here to stay. The big question is how we are going to manage this problem, mitigate its
impact, rehabilitate areas that can still be rehabilitated or are worthwhile to restore, and
prevent future encroachment.
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It is however very important to realise that the only effective way of management will be at
district or catchment level and not at farm level. Infestations need to be eradicated as total
populations and not just as small colonies between farm boundaries. This will be a huge
challenge and will probably need a significant amount of dedicated funding from
government’s treasury.
This brings us to the issue of prevention and mitigation. If each farmer is willing to take
responsibility for his own farm, even if it’s not through control but only prevention, the war
is already half won. Contain heavily infested areas and aggressively eradicate every plant
that dares to grow within the buffer zone of this area. Also regularly inspect healthy,
uninfected veld for signs of seedlings and immediately act. Then, as money becomes
available or aid schemes from government, treat the heavy infested populations and make
sure that there will be a follow-up plan for at least 5 years afterwards. Prevent excessive
seed dispersal by not moving uprooted plants from one area to another. Browsing, slashing
or burning just before plants started to seed may contribute to success.
5.2. Monitoring and research
The effectiveness of management of almost anything relies on the research behind it. Just
think how much research already gone into herbicide development for example. For
Bankrupt bush to be effectively managed, a lot of research is still needed. The first question
on where it occurs and to what extent, is already answered at a national level by this survey.
The monitoring will need to continue to paint a clear picture on the success or failure of
efforts to contain this problem. One of the most promising advancements in the field of
monitoring is the use of satellite imagery and spectral signatures to identify certain species.
If this can be done for Bankrupt bush, it will enable us to monitor on a much finer scale,
identify priority areas of intervention and rapidly respond when new populations appears in
an area. Research gaps include the following:
The habitat description of Seriphium plumosum at a national scale.
The viability of seed under natural conditions
The impact of both large and small stock digestive system on the viability of the
seed of Seriphium plumosum.
Probable use of the essential oils in the plants.
Investigate natural enemies to control plant numbers (e.g. gals killing some plants)
41 | P a g e
Quantitative measurements on the impact of animals (browsing, trampling, dung)
on the survival of the seedlings and mature plants.
Herbicides with less impact on the environment but more effective on woody
dwarf shrubs.
5.4 Closing comments
As shown in this survey, Bankrupt bush has been with us for many decades. At first you only see
one or two near a fence line, and after another year you find a small population within a road
reserve, and then, one morning after a few decades, you find nothing else but Bankrupt bush on
your farm!
In this current period that we are moving towards, climate change will increasingly play a role in
the appearance of indigenous woody species that started to encroach our precious grazing land,
slowly at first, but then, one morning ………
It is extremely important that when farmers look at their veld, that they will look at it from an
holistic way and not just concentrate on one problem, but rather see how to influence the
overall health of the agro-ecosystems, that provides production, ecological as well as social
cultural services needed to maintain and enhance their livelihoods, if used in a sustainable and
in an environmental friendly way.
Any farmer who is serious about farming will realise that he or she farms with the natural
agricultural resource, in this case rangeland and not the commodity (livestock). Farmers
neglecting or ignoring their duty as caretakers of the natural resources and who do not prioritize
the protection, conservation and sustainable use thereof, may just as well declare a state of
bankruptcy – which will happen if you ignore the threat of Bankrupt bush!
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6. References
BADENHORST & REYNOLDS 2004. PlantZAfrica.com website. South African National Biodiversity
Institute. Cape Town.
COLEMAN, A. 2010. Great strides in the fight against Slangbos encroachment. Game & Environment.
Farmers Weekly. 5 February 2010 edition. p.60-61.
DU TOIT, J.C.O. & SEKWADI K.P. 2012. Tebuthiuron residues remain active in soil for at least eight
years in a semi-arid grassland, South Africa. African Journal & Forage Science. 29(2): 85-90.
FEEDLOT ASSOCIATION OF SOUTH-AFRICA website: http://www.safeedlot.co.za – For livestock
prices mentioned in Chapter 4.5.3
JORDAAN F.P. & JORDAAN D.G. 2012. Seriphium plumosum, Bankrotbos – Die weiveld dief in die
Noordwes Provinsie. Department Agriculture and Rural Development, North West Provincial
Government.
KRUPKO, IRENA & DAVIDSON, R.L. 1961. An experimental study of Stoebe vulgaris in relation to
grazing and burning. Empire Journal of Experimental Agriculture. 29:175-180.
MUCINA, L. & RUTHERFORD, M.C. (eds) 2006. The vegetation of South Africa, Lesotho and
Swaziland. Strelitzia 19. South African National Biodiversity Institute, Pretoria.
ROUX, E. 1969. Bankrotbos. In: Roux, W.M. (Ed.), Grass, A story of Frankenwald. Oxford University
Press, Cape Town. p153-159.
SNYMAN, H.A. 2009. A philosophical approach to the distribution and spread of Seriphium
plumosum. Grassroots; publication of the Grassland Society of Southern Africa. Vol. 9 (2).
p. 29-37.
SNYMAN, H.A. 2010. Knowledge of seed ecology essential for Seriphium plumosum control.
Grassroots; publication of the Grassland Society of Southern Africa. Vol. 10 (1). p. 9-14.
SNYMAN, H.A. 2012. Habitat preferences of the encroacher shrub, Seriphium plumosum. South
African Journal of Botany. 81: 34-39.
VAN WYK, A.E & MALAN, S.J. 1997. Field Guide to the Wild Flowers of the Highveld. Struik, Cape
Town. p44 & 272.
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WEPENER, J.P. 2007. The control of Stoebe vulgaris encroachment in the Hartebeesfontein area of
the North West Province. North-West University, South Africa.