Selectivity and mode of action of flamprop-isopropyl,isopropyl (±)-2-[N-(3-chloro-4-fluorophenyl)benzamido]propionate,in the control of Avena fatua in barley |
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| Authors: | Brian Jeffcoat W Norton Harries |
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| Abstract: | The post-emergence herbicide isopropyl (±)-2-N-(3-chloro-4-fluorophenyl)benzamido]propionate (flamprop-isopropyl) showed good activity against wild oat with selectivity in barley. The basis for activity and selectivity was similar to that previously established for benzoylprop-ethyl, and found to be dependent on its rate of degradation to the biologically active acid flamprop. Flamprop stunted the growth of the oat by inhibiting cell elongation and showed a relatively high rate of movement in the phloem, approximately five times that of benzoylprop. Selectivity of flamprop-isopropyl was dependent on its relative rate of hydrolysis and the subsequent detoxication of the acid to inactive conjugates. However, although the relative rate of de-esterification of flamprop-isopropyl was lower than that of benzoylprop-ethyl similar quantities of the parent ester gave comparable effects on oat. The inherent activity of flamprop is approximately twice that of benzoylprop. The effect of flamprop-isopropyl was best seen when the compound was applied during growth stages when the crop could offer the most effective competition to the wild oat. Throughout a range of growth stages the rate of hydrolysis of flamprop-isopropyl was higher in oat than in barley. The metabolism of the compound was not markedly affected when the plants were under stress. |
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