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Diquat does not make glyphosate more effective – study


October 7, 2008
By Weed Science Society of America

Topics

dandelionOctober 3, 2008 – The long-term
success of glyphosate is hindered by diquat, a common additive,
according to a study recently published in Weed Technology.

October 3, 2008 – The long-term success of glyphosate is hindered by diquat, a common additive, according to a study recently published in Weed Technology.
 
dandelionThis finding is significant because it contradicts the widely held belief that diquat improves the efficiency of glyphosate by increasing the speed of its phytotoxic effects.
 
Regression analyses of experiments conducted by the researchers revealed that the amount of glyphosate had to be increased by 60 per cent to compensate for the reduced efficiency noted when both glyphosate and diquat were applied to the weeds used in the study. In terms of weed control products, then, “less is more,” but only when glyphosate alone is used.
 
It is true that short-term satisfaction is gained in terms of quick wilting and dehydration when both glyphosate and diquat are applied to weeds. However, the presence of diquat causes tissue necrosis, which prevents glyphosate from entering the weed’s vascular tissue. When this occurs, the glyphosate is only able to infiltrate the plant to a limited extent and the weed is thus more easily able to recover or regrow.
 
Although the authors of this study confirmed that diquat’s presence does in fact cause rapid visual signs of weed damage, it does so at the expense of long-term weed control.
 
To read the entire study, visit http://www.allenpress.com/pdf/wete-22-03-472-476.pdf.
 
For more information, visit http://www.wssa.net/.

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