These 5 Weeds Had Soybean Farmers Spooked in 2021 | The More You Grow | Corteva Agriscience
 10/25/2021

These 5 Weeds Had Soybean Farmers Spooked in 2021

Weed in soybean field top view

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