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Posted 31 August 2016. PMN Crop News.

Don’t Skimp When it Comes to Waterhemp Control

Source: University of Missouri Press Release.

Columbia, Missouri (August 11, 2016)--Do not try to save money when it comes to control of waterhemp, the biggest weed problem for Missouri soybean growers.


Waterhemp requires full force, says University of Missouri Extension weed scientist Kevin Bradley.

He says to control with a multi-layer approach to stop its spread.

Use of multiple herbicides is more effective than rotating one herbicide from year to year. “Mixing effective herbicide mechanisms of action is better than rotation,” he says.

Do not economize. Use full rates of pre-emergence residual herbicides for the cleanest fields.

“Overlapping” or “layered residual programs” worked best to kill waterhemp in research conducted at the University of Missouri Bradford Research Farm, Bradley says.

Overlap herbicides by putting on a residual herbicide at planting, and then a second residual postemerge for best control.

Recent weather patterns with continual rains show why overlapping herbicides is effective. Overlap is insurance, Bradley says.

Approximately 40 percent of Missouri soybean farmers now use Liberty Link varieties. Bradley says this is almost certainly due to the ability of Liberty to control resistant waterhemp, if used correctly. Liberty requires higher application volumes and must be applied to waterhemp less than 4 inches in height in order to be effective.

Herbicides alone cannot control waterhemp. “Farming practices such as narrow row spacing, optimum plant population, cover crops and tillage are other cultural control options that need to be integrated into a system with herbicides to achieve optimum control,” Bradley says.

Herbicides are just another tool in the toolbox, he says. Farmers should not depend solely upon them.

For more information on waterhemp management, go to You can also follow at

Kevin Bradley