These 5 Weeds Had Soybean Farmers Spooked in 2021
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In the spirit of Halloween, we’re taking a look at some of the weeds that gave soybean farmers a fright in 2021. Far from being a treat, there were five tricky varieties that popped up in Midwest fields threatening to rob yield and cause nightmares this year.
We spoke with two market development specialists (MDS) from Corteva Agriscience about these weeds and how farmers can keep them from wreaking havoc in the future.
Weeds That Caused a Fright
Giant ragweed
So what were the five weed varieties causing a fright this season?
In Minnesota and Wisconsin, MDS Jeff Moon says there were three in particular giving soybean farmers a scare: “Waterhemp, giant ragweed and lambsquarters remain the most troublesome weeds for soybeans in my geography.”
And in Nebraska, MDS Jason Gibson says he also found three weed varieties causing the most mischief: “Waterhemp, Palmer amaranth and kochia are the most difficult weeds for soybean fields in my territory.”
Waterhemp was the only overlap between the two territories, but both Gibson and Moon say farmers across the Midwest should be on the lookout for all five of these weeds. That’s because all of them have shown instances of herbicide resistance, and all of them are capable of limiting soybean yield.
Gibson and Moon say the weeds they mentioned have historically caused trouble in their given geographies. Moon also mentioned he is starting to see growing problems with weeds like velvetleaf, common ragweed. So it doesn’t hurt for farmers to be aware of those as well.
What Makes These Weeds Frightening
Palmer amaranth
As previously mentioned, these weeds can cause a fright because they have developed some herbicide resistance and can cause soybean yield loss. However, those aren’t the only reasons. Gibson and Moon say these weeds are all particularly difficult to control even without the resistance issues.
“Palmer amaranth grows very fast and has a long germination window. Waterhemp has a very long germination window. Kochia germinates in early spring; its seedlings establish quickly, and there are only a few effective postemergence control options for it,” Gibson says.
Moon says: “In general, it is difficult to get season-long control of broadleaf weeds in soybeans. With resistance issues and long germination periods, you need to employ multiple modes of action throughout the season to achieve good results. Also, these weeds are prolific seed producers, so if you have a few survivors from previous years, you can get behind in a hurry when it comes to keeping your fields clean.”
“In general, it is difficult to get season-long control of broadleaf weeds in soybeans. With resistance issues and long germination periods, you need to employ multiple modes of action throughout the season to achieve good results.”
How to Control These Weeds
Lambsquarters
The best way to keep these weeds from creating a scary situation is to plan a program approach to control them. Gibson and Moon advise making burndown applications as well as pre- and postemergence applications with multiple modes of action and residual activity.
“For Palmer amaranth and waterhemp, I recommend preemergence tank mixes or premix herbicides at planting with two or three effective sites of action, followed by a postemergence application within 30 days of the preemergence application. All post applications should include a residual herbicide,” Gibson says. “For kochia, I recommend a weed control program that includes a fall burndown application with the active ingredient sulfentrazone to provide the best opportunity to control this weed as it begins to emerge below the soil surface.”
“At Corteva, we have a deep portfolio of products to help control all the weeds mentioned in this article, regardless of how you farm — conventional till, no-till, ridge-till, etc.,” Moon says.
Kochia
When it comes to exact products, Sonic® herbicide is a good burndown or preemergence choice that contains sulfentrazone. Kyber™ herbicide is another excellent choice for a preemergence application that offers extended residual control. And for postemergence applications, EverpreX® herbicide provides extended residual control and can be used with a wide array of soybean seed varieties, including Enlist E3® soybeans. Enlist One® herbicide and Enlist Duo® herbicide also are excellent for postemergence control of these five weeds in E3 soybeans.
“At Corteva, we have a deep portfolio of products to help control all the weeds mentioned in this article, regardless of how you farm.”
Waterhemp, Palmer amaranth, kochia, giant ragweed and lambsquarters can be frightening, but they don’t have to be. They’re also far from the only troublesome weeds you might find in Midwest soybean fields. So be on the lookout for difficult varieties in your area, and work with your trusted advisors to come up with the right plan to keep those weeds under control — because the weeds should be afraid of you, not the other way around.
The transgenic soybean event in Enlist E3® soybeans is jointly developed and owned by Corteva Agriscience and M.S. Technologies L.L.C. EverpreX®, Kyber™ and Sonic® are not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Consult the label before purchase or use for full details. Enlist Duo® and Enlist One® herbicides are not registered for sale or use in all states or counties. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your area. Enlist Duo and Enlist One are the only 2,4-D products authorized for use with Enlist crops. Consult Enlist herbicide labels for weed species controlled. Always read and follow label directions.
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