Farm Fresh: What is a Super Weed?

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by Brian Hefty


Lately I have heard several media references to “Super Weeds.” For some reason people think it’s a really big deal that a handful of weed species aren’t well-controlled anymore by glyphosate, the active ingredient in Roundup. I will tell you why I don’t believe in Super Weeds and what farmers can do to quickly and inexpensively eliminate these problem weeds.


Weed control is essential to the achievement of high yields. Crops produce the most grain when they have zero competition for water, nutrients and sunlight. Prior to the introduction of Roundup Ready crops, there were a lot of weedy fields, which partially explains why yields have gone up approximately 50% in corn and soybeans in the last 20 years.


Occasionally, we will get suggestions from non-farmers to “let the weeds grow,” as diverse plant species are good for the environment. We definitely believe that a wide variety of plants are needed in nature. However, according to the U.S. Department of Agriculture, there are approximately 2.3 billion total acres in the U.S. We are only producing crops on about 20% of those acres. In other words, it is a small percentage of our land that we use to produce crops, and crops grow best in the absence of weeds.


Coming back to the “Super Weeds” the media refer to, they include: Palmer pigweed, waterhemp, marestail, giant ragweed, common ragweed and kochia. All of these have biotypes resistant to glyphosate in one or more states in the U.S. today. The reason why I call none of these Super Weeds is we can control them all with current technology and future technology will give us even more options.


First, none of these is resistant to tillage. I’m not saying all farmers should till, but for those who do, their problems are greatly reduced.


Second, crops can choke out weeds themselves if they get off to a good start and grow quickly. Using proper fertility, drainage, seed variety selection and seed treatments all help greatly with this.


Finally, all it takes is a simple switch of herbicides to stop these weeds. We are very fortunate in modern agriculture that we have many safe, effective products to help control weeds. Many of these have been derived from nature, which is exactly what we’re looking for. For example, Callisto herbicide was discovered when a researcher had a callistemon tree in his back yard. He noticed there were no broadleaf weeds growing near the tree (including the “Super Weed” list I just gave you), so he and his team began isolating the compound in the tree that was killing the weeds. Today, there are many different herbicides in that same family that all began by using nature’s own methods of controlling weeds.


In the near future, we expect to have even more safe, effective and quite often natural ways to control weeds in our crops. The science involved today in agriculture is incredible and only getting better.


So the next time you hear someone talk about Super Weeds, just remember that there is no weed we can’t control in corn or soybeans today with the right season-long management. That’s part of the reason I predict yields will continue to climb in the next few years.



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Farm Fresh: What is a Super Weed?

by Brian Hefty

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