Future Directions:

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Future Directions Alligator-Weed Research and
Management
Shon Schooler CSIRO Entomology Shon.Schooler_at_csi
ro.au
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Goal To identify key questions and develop
research projects that will increase our
understanding of alligator-weed and lead to more
effective management strategies.
Chemical Mechanical Cultural Biological
Integrated
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• Current Research Projects
• Genetic analysis
• Pollination study
• Karyotype analysis
• Integrated management strategies
• Herbicide trials
• Comparison of management methods
• Field biomass measurements (modelling)
• Ideas for Future Research

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• Herbicide Trials
• Tom Anderson Queensland Natural Resource
  Management
• (Tom.Anderson_at_nrm.qld.gov.au)
• Greenhouse Trials
• Triclopyr amine (selective (no grasses) and best
  over long term)
• Glyphosate (non-selective but works ok)
• Carfentrazone (quick knock down but does not get
  to roots)

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Effect of herbicide, repeated leaf removal, and
single event complete above ground biomass
removal on the production, nutrient, and stored
energy allocation of alligator weed
(Alternanthera philoxeroides)       Alice Yeates,
John Wilson, Mic Julien, Shon Schooler, and
Leanne Hughes
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440 plants over 5 weeks Treatments 1) Stems
clipped (once) 2) Herbicide (Glyphosate 360g/L
) 3) Defoliation (weekly) 4) Control
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Treatments and Biomass
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Nutrient Analysis
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Treatment Effect Total Cumulative Biomass
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Treatment Effect Shoots vs. Roots
Stems and Leaves
Roots
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Biomass Collections NSW Agriculture Weeds
Research Unit Port Stephen Shire Council Graham
Prichard Bertie Hennecke Tony Cook Paul Moylan
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Future Questions
  Research Topic 1 Feeding damage of biocontrol
agents. How do different types of herbivory
affect plant growth? Can the strategic removal
of small amounts of tissue have the same impact
as general defoliation (ie. tip destruction vs.
leaf removal)? Does node damage effect root
growth at the node?  
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Future Questions
  Research Topic 2 Plant spread via nodes.
Do habitat conditions affect fragmentation?
What is the fate of fragments/nodes ? How
long can they (and what fraction) can survive
adverse conditions (temperature, desiccation,
submergence, etc)?  
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Future Questions
  Research Topic 3 The root bank. It has
been observed that flooding can trigger a flush
of growth that has been mistaken for seedlings.
Greenhouse observations have found that roots
can be completely dry for several weeks and then
sprout after they are re-hydrated. What is the
fate of roots under adverse conditions?  
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Future Questions
  Research Topic 4 Herbivory and disturbance
mediating competitive outcomes. When
conditions are favourable (water present and
herbivores absent) alligator weed can colonize
large areas very quickly. However, with
decreasing moisture and increasing herbivory
alligator weed begins to loose ground and
above-ground material eventually disappears.
How do flooding and herbivory interact to
influence the competitive ability of alligator
weed? When is population growth reduced to
zero?  
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Future Questions
  Research Topic 5 Climate matching for new
agents. One goal of this project is to release
agents that will control alligator-weed in cooler
climates. Can we predict the effectiveness of
potential agents using using CLIMEX and GIS
models? This is particularly relevant because
the terrestrial herbivores (the second goal) will
be more affected by climatic conditions.
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Building models of plant population
dynamics What factor or combination of factors
will lead to a decline in alligator-weed biomass?
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Discussion