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\hypersetup{pdftitle={Weed Control with Natural Herbicides in Grain Legume Row Crops},pdfauthor={Michael Giepen},pdfsubject={Tropentag 2016: Abstract},pdfkeywords={Cell membrane disruptor , direct seeding, natural herbicide, organic agriculture},pdfpagemode=None,colorlinks=true}
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\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, September 18-21, 2016, Vienna, Austria}}\\[1ex] \Large{``Solidarity in a competing world ---\\fair use of resources''\\[2ex]}}
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\Large{\textbf{Weed Control with Natural Herbicides in Grain Legume Row Crops\footnote{\textbf{Contact Address:} Michael Giepen, Bonn University, Iol, Katzenburgweg 3, 53115~Bonn, Germany, \mbox{e-mail}: \email{mgiepen@uni-bonn.de}}\\[0.8ex]}}
\normalsize{\textsc{Michael Giepen}}
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\begin{itemize*}
\item[]{\small{\textit{Bonn University, Iol, Germany}}}
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\index[author]{Giepen, Michael}
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\textbf{Abstract}
\begin{abstract}
\normalsize{
To enable direct"=seeding of grain legumes in Oorganic Agriculture (OA) natural herbicides (NH) are assumed to be a prerequesite, therefore formulations of natural herbicides (NH) were studied in screening and field trials in Paraná state, Brazil.



Active ingredients (AI) in commercial formulations are cell"=membrane-disruptors (CMD) such as essential oils, pelargonic and acetic acid (AA).   Their effect is not systemic, and plant recovery happens quickly.   With elevated costs these formulations are not viable for use in agricultural practice.



However, the addition of NaCl to CMD formulations containing the CMD delta"=limonene and pine oil at doses of \unitfrac[50]{kg}{ha} prooved to enhance the herbicidal effect considerably by adding osmotic stress and systemic NaCl toxicity.   Non"=contacted plant meristems frequently die off, killing plants or retarding resprouting considerably.  Expensive CMD ingredients could thereby be reduced from \unitfrac[200]{L}{ha} to \unitfrac[50]{L}{ha}.  



For acceptable weed control application in soybean and common bean two or three applications were necessary.   Furthermore, results suggest that application of CMD+NaCl formulations should occur during the hours with highest temperatures and irradiation to maximise the herbicidal effect.  CMD+NaCl show good control of



weeds if applied at early development stages and if subsequent applications are timed correctly.  Most dicots can be controlled up to 4 leaf and monocots up to 2 leaf stage.



Emulsifiers do not only affect herbicidal effect of NH through emulsion stability but were proven to have a herbicidal effect of their own at the large quantities applied in NH formulations.   For NH to become applicable, effective natural AI and emulsifiers have to be found as these are currently synthetic and in part even harmful to the environment.   The state"=of-the art of NH in OA and describes possibilities to enhance formulations with other phytotoxic salts and AI with systemic action, and obstacles for use in OA practice are resumed.



}

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\noindent \textbf{Keywords:} Cell membrane disruptor , direct seeding, natural herbicide, organic agriculture
\index[key]{Cell membrane disruptor }
\index[key]{Direct seeding}
\index[key]{Natural!herbicide}
\index[key]{Organic!agriculture}
\end{document}
