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Mechanism of selectivity of diquat solutions in poppy. (Papaver somniferum L.)


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Barnes, CD 1994 , 'Mechanism of selectivity of diquat solutions in poppy. (Papaver somniferum L.)', Honours thesis, University of Tasmania.

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The current mechanisms of herbicide selectivity in poppy (Papaver somniferum L.)
were examined in glasshouse and field experiments.
Through measurements of contact angles of diquat solutions it was established that
poppy, and the weeds fumitory, fat hen and field poppy are 'hard' to wet, whilst
shepherds purse, wild radish, spear thistle and curled dock are relatively 'easy' to wet. It
was revealed that diclofop-methyl has properties characteristic of a weak surfactant,
compared with Agral®, a finding supported through measurements of dynamic surface
The structure of the surface wax on the adaxial surface of poppy, field poppy,
fumitory and fat hen leaves are described as seen under the scanning electron
microscope. Chemical analysis of these waxes are also given. It appears the wax of
fumitory and fat hen are influenced by application of ethofumesate.
Chemical analysis shows that ethofumesate can inhibit the deposition of primary
alcohols, long chain aldehydes and alkanes on the developing leaves of fumitory and fat
hen, making these plants more susceptible than poppy plants to future applications of
diquat + diclofop-methyl.
Field trials conducted on the east and north-west of Tasmania, highlighted the
difficulties that exist in extrapolating results from glasshouse experiments to field
conditions. Measurements of spray retention and efficacy, revealed that plant responses
to applications of diquat treatments were influenced, in addition to ethofumesate, by
environmental conditions.
Plant responses at both sites demonstrated that the inert ingredients of the
commercial formulation of diclofop-methyl, would, in admixture with diquat produce the
same result compared with the current diquat/diclofop-methyl treatment

Item Type: Thesis - Honours
Authors/Creators:Barnes, CD
Keywords: poppy,Papaver somniferum L., herbicide selectivity,ethofumesate,diquat solutions
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