Dr' Steven Robert Harris

1
Presentation Title
The Case for Non-Chemical Approaches to the
Knotweed Problem

• Dr. Steven Robert Harris
• University of Glamorgan
• Faculty of Health, Sport and Science

2
The Case

• Two Questions
• Two Key Considerations
• Two principles
• Conclusions
• My Recommendations

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Two Questions

• There are two questions which need clear answers
  before making any intervention
• What are our main aims in seeking to remove or
  control the Japanese Knotweed in this specific
  area?
• Given the resources and methods available to us,
  which methods offer us the best chance of success
  at the lowest human, environmental and economic
  cost?

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Two Key Considerations

• The impact of Climate Change on the Valleys of
  south Wales
• The increasing cost of energy and materials
  derived from non-renewable resources (oil, coal,
  gas)

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The Impact of Climate Change

• Warmer, wetter winters
• Hotter, drier summers
• Increased occurrence of extreme weather events
  (storms and flooding, heat waves and drought)
• Unpredictable impacts on existing ecosystems,
  e.g. with regard to invasive species

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The increasing cost of energy and materials

• PEAK WEEDKILLER?
• lately, the farming press has been sounding the
  alarm on a new danger -- price hikes for
  glyphosate -- a.k.a. Monsanto's RoundUp -- are
  also heading sky-high. ...
• But demand, whether propelled by biofuels,
  changing diets, isn't the only reason for the
  price rise. So is scarcity of a key ingredient
  phosphorus.
• ...rock phosphate, the source of nearly all
  industrially-used phosphorus, is a non-renewable
  resource, and some scientists think reserves will
  run out within the next 40 to 50 years
• From article by Andrew Leonard in the Energy
  Bulletin, April 11 2008

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Two Principles

• The Precautionary Principle If in doubt,
  dont
• The Problem is the Solution Focus on
  opportunities rather than obstacles

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The Precautionary Principle

• It is the responsibility of an activity
  proponent to establish that the proposed activity
  will not (or is very unlikely to) result in
  significant harm
• Despite the claims of manufacturers, independent
  research (see e.g. Buffin and Jewell 2001) raises
  persistent and serious doubts about the long-term
  effects of herbicides on environmental and human
  health - In the case of Glyphosate, watercourse
  pollution is of particular concern
• In a situation where we expect to experience many
  more heavy rainfall events, should we risk
  increasing soil erosion and riverbank instability
  through Knotweed removal?

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The Problem is the Solution

• Permaculture is the practice of designing
  sustainable human habitats by following nature's
  patterns. Applying its principles, we might
  consider that the Knotweed problem might also
  be an opportunity to
• Catch and store energy Make hay while the sun
  shines through carbon sequestration and
  biomass production
• Obtain a yield You cant work on an empty
  stomach Knotweed can be eaten directly by
  humans or converted to usable proteins by grazing
  animals who also produce manure
• Use and value renewable energy and resources
  Let nature take its course we cant predict
  how other species may displace/predate/parasitize
  Knotweed and right now it greens many of our
  ugliest, litter-strewn landscapes
• Produce no waste Waste not want not dead
  knotweed can also offer a big (expensive, ugly)
  challenge!
• Use small and slow solutions Slow and steady
  wins the race and The bigger they are, the
  harder they fall patience, nature may solve
  the bigger problem for us meanwhile, lets
  favour very small solutions

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Two Conclusions 1

• Any attempt to control and/or clear Knotweed
  using energy-intensive methods is likely to prove
  very expensive in human, economic and
  environmental terms
• and with some methods there is not only little
  certainty of a successful outcome (except on
  small areas over a short timescale) but also some
  real possibility of serious harm

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Conclusions

• Therefore, in those situations where it is vital
  to control the Knotweed, the best solutions are
  those which minimise the energy cost while
  maximising the energy return i.e. where the
  problem becomes the solution

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My Recommendations

• In the light of the two key considerations and
  two principles, sort the available control
  methods into two categories acceptable and
  unacceptable
• Within those categories, place methods in order
  of preference
• Use this categorisation and ordering to answer
  the two questions in relation to a specific
  location

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Control Methods

• Dig Dump
• Root Barrier Membrane
• Pulling or Mowing
• Grazing
• Chemical Herbicides
• Do Nothing!
• Biological Control
• Combined Treatment

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Control Methods

• Acceptable, in order of preference
• Do Nothing!
• Grazing
• Biological Control
• Pulling or Mowing
• Root Barrier Membrane
• Dig Dump
• Unacceptable
• Combined Treatment
• Chemical Herbicides

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Presentation Title

• Thank you!