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Weed Control Additive Diquat Does Not Make Glyphosate More Effective

published: September 16th 2008
source: Weed Technology

The long-term success of glyphosate, the main component of many weed control products, is hindered by diquat, a common additive, according to a study recently published in Weed Technology.

This 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% 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

About Weed Technology

Weed Technology is a quarterly publication of the Weed Science Society of America, a nonprofit professional society that promotes weed research, provides science-based information about weeds to the public and policy makers, and increases society’s awareness of weeds and their effect on managed and natural ecosystems. For more information, visit http://www.wssa.net/