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Know herbicide mode of action and control resistant weeds with online toolKnow herbicide mode of action and control resistant weeds with online tool

Use all the tools at your disposal to fight herbicide-resistant weeds, including a herbicide mode of action website bookmarked on your smartphone.

Jennifer Campbell 1

April 23, 2015

2 Min Read

Herbicide-resistant weeds, such as Palmer Amaranth, are a known threat. These weeds can spread quickly, reduce land values and threaten yields if not effectively managed.

Related: Fight Resistant Weeds by Knowing Modes of Action

While most farmers are aware of the problem, increased management is needed to control farm field weeds, according to Mike Marshall, extension weed specialist at Clemson University.

"The level of management is not where I would like to see it," Marshall said of the resistant weeds issue. "I would like to see farmers spend more of their resources and time on soybeans. In the past, weed problems got out of hand because the necessary level of management was not there."


Timing is crucial to good field weed control, according to Marshall. "It all boils down to timing, if you wait a week to 10 days to spray emerged weeds, your expected control can drop off significantly, especially with Palmer Amaranth."

For maximum weed control, Marshall suggests that farmers get out in their fields and scout for weeds on a regular basis.

Know mode of action with USB's online tool
In addition to scouting and identifying species, understanding mode of action will help weed control and prevent herbicide resistance. A good resource is the Site of Action Lookup Tool offered by the United Soybean Board.

Accessible from your desktop or mobile device, the website specifies the mode of action of an herbicide, and identifies other herbicides that fall within that same site of action, allowing a grower to utilize herbicides from different groups to spread out the risk of resistance.

Related: The Future in Weed Control Will Be Talking 'Mode of Action'

The Site of Action Lookup Tool allows you to search by herbicide trade name, or active ingredient, and you can download a digital copy of the full chart that details the site of action of most popular herbicides and premixes.

With the right information and the proper herbicides applied properly, weed resistance can be avoided.

In the coffee shop, it is known as Palmer pigweed. In university circles, it is referred to as Palmer amaranth. Whatever you want to call it, this weed is the No. 1 weed to watch. Stay on top of your control plan with our new free report, Palmer Amaranth: Understanding the Profit Siphon in your Field.

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