2. Leguminous woody perennial shrub which can fix N
Maximum 2-6 m in Height at maturity
Bipennate leaves are sensitive and fold up once touched or nightfall
Flower heads containing approximately 100 flowers.
Each flower head produces a cluster of 10 to 20 seedpods
Oblong shaped seed having hairs to float on water and stick
Hard seed coat
Introduction to Mimosa pigra
3. Native to tropical America
Grow natively as scattered seldom plant in 2m height
Widespread throughout the wet areas in tropics including Australia and Asia.
One of the world's 100 worst invasive species
Forms dense, thorny, thickets populations covering large extent once invade
Problematic weed in Agricultural & environmental aspects
Global Context of Mimosa pigra
4. First reported around Mahaweil river bank in Thennekumbura, Sri Lanka in 1997
Entered with heavy machineries imported from Australia for Mahaweli project
Covered a 20–25 km strip along the banks of the Mahaweli River by 2000
Central and north-western provinces of Sri Lanka
Abandoned paddy fields, river or stream banks and new construction sites.
Local context of Mimosa pigra
5. Flowering at 12–14 weeks after planting
The relative growth rate (RGR) increased until onset of flowers and then
decreased.
Reproduce only by seed
Abundant seed production (9000 seeds per square meter annually)
Long-lived seed bank (>10 Y) in soil (23 Y in sandy soil)
Seed viability decreases more rapidly on clay soil
Soil seed-bank density within the canopy diameter is 2,336 to 46,410
seeds per square meter
Propagation of Mimosa pigra
6. 100% viable after four years of storage
at room temperature
After sand scarification, 99% of seeds
germinated due to break of seeds
dormancy
Seed Dormancy of Mimosa pigra
Figure 1: Germination percentage of mimosa seeds
Source: Buddhi, M 2002, Distribution, biology and
management of Mimosa pigra in Sri Lanka, graph,
https://www.researchgate.net/publication/242701381
7. Mimosa pigra as an
Invasive Plant
First reported in Sri Lanka in early 1996
First identified Central and North-
western provinces of Sri Lanka,
Colonized along the river banks of
Mahaweli river.
Seed disperse with river sand that is used
for construction work
And with river water flow
Reproduces only by seeds
8. Why invasive
Non- Native Plant
A serious agricultural, environmental and
economic problem in Sri Lanka and also in many
other countries
Rapid spreading at alarming rate
Removing native vegetation and altering
the availability of water and nutrients
the height increased at a rate of 2.4-2.6 cm per
day during the first 8-12 weeks
•
9. Why invasive(continuous)
• Seed disperse
• with river water and river sand that is
used for construction work
• High soil seed bank density,
• within the canopy diameter of the
naturally grown mimosa plants varied
from 2,336 to 46,410 seeds per squire
meter.
• Aggressively behavior
• The plant behave aggressively, forming
dense thickets covering large extents of
land and threatening the natural
biodiversity.
10. Why invasive ( continuous)
• Higher seed viability
• Mimosa seeds were 100%
viable after four year of
storage at room temperature
28oC and also at 8oC after
sand scarification
• and can stay at least 23 years
in sand soil.
• A perennial scattered plant
or small tree
• may grow to a height of
about 4 -6m deep root
system
13. Impact on Plants
Compete with native herbaceous plants.
Allelopathic activity that influences the
germination and growth of some plant
species.
Prevent establishment of other species.
14. Impact on Plants Cont.
It also provides cover for of rats and crabs which
damage crops.
Mimosa is able to outcompete young palm trees
in immature oil palm plantations and cause a
decrease in the production of palm oil.
Eliminate most other species of grasses and
forbs converting floodplains into unproductive
scrubland.
15. Impact on Animals
Disturb wildlife movements and their water availability from the water
front.
E.g. Population of large water birds in the M. Pigra infestation areas of
the bueng boraphet wetland in Thailand was reduced by
27% in 2003
2014 with the highest decline of 56% in ducks.
(Haq R.U., Eiam-Ampai K., Ngoprasert D., Sasaki N., Shrestha R.P.
Changing landscapes and declining populations of resident waterbirds)
17. Impact of Animals cont..
Reduce the available drinking water for cattle.
The fishing production in the river near the
floodplains was decreased in Africa.
Decrease available grazing areas for
herbivores and related carnivores including
birds and lizards.
.
19. Spread of mimosa along the Malinde Channel of the Kafue Flats, Zambia (G.
Howard)
20. Impact on Humans.
M.pigra can block roads and pathways which can limit
accessibility to crop lands.
Disturbing farming livelihoods.
E.g. Average famers spend 11 days per ha annually to
clear the species in their farmlands in the Mekong River
floodplains in Cambodia.
Disturbs the day-to-day human recreational activities and
tourism opportunities that are dependent on accessible
water bodies.
22. • Glyphosate AI 1.44 kg / Ha
effectively controlled
mimosa seedlings less than
six months old,
• Need to apply three times
at four-month intervals on
the same set of seedlings.
23. 3.Burning
High temperature that can be killed
some proportion of seed
4.Agronomic methods
Younger stage of mimosa pigra with
use of panicum maximum the seeds
of mimosa are not germinated
5.Biological control agents
Introduce insects which can be
controlled seeds, flower, stem, root
24. 6. Policy recommendation
short and long-term solution
7. Integrated management
Biological control agents with
herbicide
8. Prevention
Map infestation before
commencing control to enable
the development of a
coordinated management
strategy
25. References
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Northern Territory Government,Australia
