COOMERA RIVER Aquatic weed control program Eye bag removal by benbenzhou


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            Aquatic Weed
      Management Program

          Pest Management Unit
         Gold Coast City Council
Why such a problem?
   Blocked & Choked Waterways
   Restirct Access to stock
   Inhibit Recreational Activity (fishing,
    boating etc.
   Easily spread –
       Birds
       People – on boats & equipment, intentionally.
       Set from broken stems as well as seed.
   Physical/Mechanical Control
       Ecologically sound if done correctly
       Expensive – time & equipment
   Biological Control
       Usually uses insects
       Slow, no immediately obvious result
   Chemical Control
       Cost effective
       Immediate results
       Can be an environmental concern
   Community Education
       Potentially very helpful
       Subjective – reliant on members of public
Declared Water Weeds in Gold
Coast Catchments.
   Senegal Tea Plant – Class 1
   Glush Weed – Class 1
   Alligator Weed – Class 1
   Cabomba – Class 2
   Water Hyacinth – Class 2
   Water Lettuce - Class 2
   Salvinia – Class 2
Class 1

             Glush Weed

                           Senegal Tea

                   Alligator
                  Salvinia

                        Water Lettuce

                                            Cabomba

   Water Hyacinth
Senegal Tea Plant
   Class 1 Declared
   Native of South
   Physical control
   Herbicice –
    Roundup BiActive
Water Lettuce – Pistia stratiotes
   Class 2 Declared
   Native of South
   Control = removal
    and herbicide.
   Bio-control – 2 weevil
Water Hyacinth – Eichornia crassipes

   Class 2 declared
   Native of South
   Control – removal and
   Bio-control – 2
    weevils & 2 moths
   Class 2 Declared
   Native of South
   Control = removal
    and herbicide.
   Bio-control – weevil
Heavy infestation of Aquatic Weeds –
Coomera Weir, November 2003
Coomera River Weir
                Mechanical Control

   Removal of weeds was the best option
   Infestation was too big to consider
    chemical control
       Dead plants would have sunk to the bottom
        and decomposed causing oxygen depletion
       Oxygen depletion has more potential to
        adversely effect aquatic life than the
        herbicides used.
Aquatic Weed Harvester Aust.
Contracted to commence mechanical
Aquatic weeds collected on a conveyor
Weeds are then transferred to a
compactor truck for removal.
Non-target water plants such as water lilies
suffer minimal damage from the harvester
Water weeds not collected by the harvester
       are controlled by herbicide.
           Biological Control
   Introduced insects most common agent for
    aquatic weeds
   Rely on optimum conditions for insect
    populations to build up quickly enough to
    control the plants.
   Different Bio-control agents for each
    aquatic weed
Biological Control of Salvinia
   Salvinia Weevil
   Used in areas where
    chemical control is
   Used in areas
    inaccessible to
Cyrtobagous salviniae
   Natural range is South America
   Salvinia is from the same geographical area
    Introduced to Australia and USA
   Has demonstrated success in both countries
   Prefers more tropical climate – Southern
    Qld/Northern NSW is at the limit of its climatic
Cyrtobagous salviniae
   Larvae mine into the heart of the plant
   Plant becomes unstable and waterlogged
   Plant eventually sinks to the bottom
   Adult weevils feed on the plant’s leaves
   Adults are capable of flight but do not
    usually travel very far from where they are
    initially released
   Larvae and Adults
    both feed on the plant
   Not a short term
    control option
   May take two years or
    longer to significantly
    reduce the infestation
   Tiny but useful tool in
    Salvinia management
Monitoring for presence of weevils.

   Adults prefer young
   Difficult to locate with
    the naked eye
   Look for damage to
    the plants
Example of plant under attack
from Cyrtobagous salviniae
 Barriers placed across the river to arrest
the spread of Salvinia and concentrate the
 introduced population of Salvinia Weevil.
        Biological Control of Water Hyacinth

   Weevils
       Neochetina eichhorniae

       Neochetina bruchi
   Moths
       Niphograpta albiguttalis

       Xubida infusella
      CLASS 1 Declared Plants
   If you find an infestation:
   Must be reported to Department of Natural
    Resources and Mines
    1800 803 788
    3227 7111
Senegal Tea Plant
Class 1 Declared Plant
Senegal Tea near
C.J. Bird bridge
Scattered infestations found between C.J. Bird bridge and
John Muntz Causeway.

                                          plotted with G.P.S.
        Senegal Tea Plant Control Options
   Physical Removal
       Small infestations can be removed and placed in
        plastic bags in the sun to rot.
       Care must be taken not to infest further areas with
        broken stems.
   Chemical Control
       No herbicides registered to control Senegal Tea
       Off-Label permit for use of Roundup Bi-Active by
        trained operators.
       Trials on-going with Alan Fletcher Research Station
        using Tordon.
Removal of Senegal Tea
Heritage Drive, Coomera River.
Removal of Senegal Tea
Plants are bagged and removed from area.
Other Class 1 Aquatic Weeds
                    Occurring in the
        Gold Coast catchment areas
Hygrophila costata
   Glush Weed
   Found in Albert River
   Similar to native
   Best controlled with
    Roundup Bi-Active or
Alligator Weed

   Althernathera philoxeroides
   Found in the Albert
    River catchment
   Grows from seed and
    broken pieces of stem
   Stems are hollow

   Cabomba caroliniana
   Found in several
    catchment areas
   Grows rapidly from
    broken pieces of stem
   Difficult to control
   Can be controlled if
    the water source can
    be drawn down.
Environmental Water Weeds
Parrot’s Feather – emergent feathery aquatic herb.
Native of South America.
Best controlled by physical removal and composting or land
burial of removed plants.
Environmental Water Weeds

 Azolla – floating native fern.
 Controlled by physical removal and floating barriers to contain
 infestations. High nutrient levels promote growth.
 Leaves turn rusty red in full sunlight
Community Involvement
   WeedBuster Week
Catchment Groups

    Information Days
    Catchment
    Stakeholder
The GCCC aquatic weed control program is
tailored to minimise the impact on wildlife
in our valuable wetland areas.
More information?
   Wetland Plants of Queensland – A Field
    Guide. K M Stephens & R M Dowling. CSIRO
    Publishing. (about $40.00)

   Department of Natural Resources & Mines fact

   Landcare Australia

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